Toward improved durability in advanced aircraft engine hot sections

NASA Technical Memorandum 4087

Toward Improved Durability

in Advanced Aircraft

Engine Hot Sections

D. E . Sokolowski, Editor

Lewis Research Center

Cleveland, Ohio

National Aeronautics and Space Administration Office of Management Scientific and Technical Information Division

CONTENTS

NASA HOST Project Overview D. E. Sokolowski . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Advanced High Temperature Instrumentation for Hot Section Research Applications D. R. Englund and R. G. Seasholfz (also NASA TM-100282) . . . . . . . . . . . . . . . . . . . . 5 Assessment, Development, and Application of Combustor Aerothermal Models J. D. Holdeman, H. C. Mongia, and E. J. Mularz (also NASA TM-100290). . . . . . . . . . . . . . . . . .

Review and Assessment of the Database and Numerical Modeling for Turbine Heat Transfer H. J. Gladden and R. J. Simoneau (also NASA TM-100280) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Structural Analysis Methods Development for Turbine Hot Section Components R. L. Thompson (also NASA TM-100298) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Structural Analysis Applications R. L. McKnight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Fatigue Life Prediction Modeling for Turbine Hot Section Materials G. R. Halford, T. G. Meyer, R. S. Nelson, D. M. Nissley, and G.A. Swanson (also NASA TM-700291) . . . . 97 Life Modeling of Thermal Barrier Coatings for Aircraft Gas Turbine Engines R. A. Miller (also NASA TM-100283) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Views on the Impact of HOST J. 6. Esgar and D. E. Sokolowski . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

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NASA HOST PROJECT OVERVIEW D. E. Sokolowrki National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio INTRODUCTION H i g h t e m p e r a t u r e m e t a l l i c m a t e r i a l s c u r r e n t l y i n c l u d e n i c k e l - and c o b a l t - b a s e d s u p e r a l l o y s . C e r t a i n S i n c e i n t r o d u c t i o n o f t h e gas t u r b i n e e n g i n e t o elements o f t h e s e a l l o y s , such as c o b a l t , a r e i n s h o r t a i r c r a f t p r o p u l s i o n , t h e q u e s t f o r g r e a t e r performance Ways f o r r e d u c i n g t h e s e s u p p l y and a r e e x p e n s i v e .

has r e s u l t e d i n a c o n t i n u i n g upward t r e n d i n o v e r a l l a l l o y i n g e l e m e n t s were p r e s e n t e d by Stephans ( 1 9 8 2 ) .

f o r t h e e n g i n e c o r e . A s s o c i a t e d w i t h p r e s s u r e r a t i o I n a d d i t i o n . advanced h i q h t e m p e r a t u r e s u p e r a l l c com- t h i s t r e n d a r e i n c r e a s i n g t e m p e r a t u r e s of gases n g l e ponents a l s o i n c l u d e d i r e c t i o n a l l y s o l i d i f i e d , s from t h e compressor and combustor and t h r o u g h f l o w i n g a l s .

c r y s t a l , and o x i d e - d i s p e r s i o n - s t r e n g t h e n e d m a t e r t h e t u r b i n e . For commercial a i r c r a f t e n g i n e s i n t h e b r i ca- Development t i m e f o r new m a t e r i a l s i s l e n g t h y , f f o r e s e e a b l e f u t u r e , compressor d i s c h a r g e t e m p e r a t u r e h i g h .

t i o n i s sometimes d i f f i c u l t , and a g a i n c o s t s a r e w i l l exceed 922 K (1200 O F ) , w h i l e t u r b i n e i n l e t tem- a b a l - Thus, s u c c e s s f u l use o f t h e s e m a t e r i a l s r e q u i r e s w i l l be a p p r o x i m a t e l y 1755 K (2700 O F ) . M i l - p e r a t u r e ance among d e s i g n r e q u i r e m e n t s , f a b r i c a t i o n poss b i l i- i t a r y a i r c r a f t e n g i n e s w i l l s i g n i f i c a n t l y exceed t h e s e t i e s . and t o t a l c o s t s .

v a l u e s .

C u r r e n t c o o l i n g t e c h n i q u e s t e n d t o be s o p h i s t i - I n c r e a s i n g f u e l p r i c e s , e s p e c i a l l y s i n c e 1973, c a t e d ; f a b r i c a t i o n i s m o d e r a t e l y d i f f i c u l t . I n h i g h e r have c r e a t e d t h e demand f o r e n e r g y c o n s e r v a t i o n and performance e n g i n e s , c o o l i n g c a p a b i l i t y may be improved more f u e l e f f i c i e n t a i r c r a f t e n g i n e s . I n response t o There i s a pen- b y i n c r e a s i n g t h e amount o f c o o l a n t .

t h i s demand, e n g i n e m a n u f a c t u r e r s c o n t i n u a l l y i n c r e a s e d a l t y for d o i n g t h i s , however, i n t h e r e d u c t i o n o f t h e r - t h e p e r f o r m a n c e o f t h e c u r r e n t g e n e r a t i o n of gas t u r - modynamic c y c l e performance o f t h e e n g i n e system. I n b i n e e n g i n e s . Soon a f t e r w a r d , t h e a i r l i n e i n d u s t r y a d d i t i o n , t h e c o o l a n t t e m p e r a t u r e o f such advanced began t o e x p e r i e n c e a n o t a b l e decrease i n d u r a b i l i t y e n g i n e s i s h i g h e r t h a n t h a t for c u r r e n t i n - s e r v i c e or u s e f u l l i f e o f c r i t i c a l p a r t s i n t h e e n g i n e c o r e e n g i n e s . Consequently, more e f f e c t i v e c o o l i n g t e c h - hot s e c t i o n -- t h e combustor and t u r b i n e . T h i s was n i q u e s a r e b e i n g i n v e s t i g a t e d . They a r e g e n e r a l l y due p r i m a r i l y t o c r a c k i n g i n t h e combustor l i n e r s , t u r - more complex i n d e s i g n , demand new f a b r i c a t i o n meth- b i n e vanes, and t u r b i n e b l a d e s . I n a d d i t i o n , s p a l l i n g ods, and may r e q u i r e a m u l t i t u d e o f s m a l l f i l m - c o o l i n g of t h e r m a l b a r r i e r c o a t i n g s t h a t p r o t e c t some combus- h o l e s , each o f which i n t r o d u c e s p o t e n t i a l l i f e - l i m i t i n g t o r l i n e r s was e v i d e n t .

h i g h s t r e s s c o n c e n t r a t i o n s . A c c e p t a b l e use of t h e For t h e a i r l i n e s reduced d u r a b i l i t y f o r i n - s e r v i c e advanced c o o l i n g t e c h n i q u e s r e q u i r e s a c c u r a t e models e n g i n e s was measured b y a d r a m a t i c i n c r e a s e i n m a i n t e - for d e s i g n a n a l y s i s .

nance c o s t s , p r i m a r i l y f o r h i g h bypass r a t i o e n g i n e s .

o f advanced s t r u c t u r a l d e s i g n con- The i n t r o d u c t i o n H i g h e r maintenance c o s t s were e s p e c i a l l y e v i d e n t i n t h e c e p t s u s u a l l y b e g i n s w i t h a p r e l i m i n a r y c o n c e p t t h a t h o t s e c t i o n . As shown b y Dennis and Cruse (1979). h o t t h e n must be p r o v e n , must be developed, and -- most s e c t i o n maintenance c o s t s a c c o u n t f o r a l m o s t 60 p e r c e n t

c r i t i c a l l y -- must be f a r s u p e r i o r t o e n t r e n c h e d stand-

of t h e e n g i n e t o t a l . Widespread c o n c e r n a b o u t such Acceptance c e r t a i n l y i s t i m e consuming, a r d d e s i g n s .

s o a r i n g maintenance c o s t s l e d t o a new demand -- t o F o r improved d u r a - and b e n e f i t s must be s i g n i f i c a n t .

improve h o t s e c t i o n d u r a b i l i t y .

l i t y i n h i g h p e r f o r m a n c e combustors, an e x c e l l e n t b i D u r a b i l i t y can be improved i n h o t s e c t i o n compo- example o f an advanced s t r u c t u r a l d e s i g n concept i s n e n t s b y u s i n g any c o m b i n a t i o n o f t h e f o l l o w i n g f o u r t h e segmented l i n e r as d i s c u s s e d b y T a n r i k u t e t a l .

approaches. They a r e t h e use o f ( 1 ) m a t e r i a l s h a v i n g ( 1 9 8 1 ) . The l i f e - l i m i t i n g problems a s s o c i a t e d w i t h h i g h e r use t e m p e r a t u r e s , ( 2 ) more e f f e c t i v e c o o l i n g h i g h hoop s t r e s s e s were e l i m i n a t e d b y d i v i d i n g t h e t e c h n i q u e s t o r e d u c e m a t e r i a l t e m p e r a t u r e s , ( 3 ) advan- s t a n d a r d f u l l - h o o p l i n e r s i n t o segments. A t t h e same ced s t r u c t u r a l d e s i g n c o n c e p t s t o reduce s t r e s s e s , and t i m e , d e s i g n e r s r e a l i z e d i n c r e a s e d f l e x i b i l i t y i n t h e ( 4 ) more a c c u r a t e a n a l y t i c a l models and computer codes c h o i c e o f advanced c o o l i n g t e c h n i q u e s and m a t e r i a l s , t o i d e n t i f y h o t s p o t s , i n t h e d e s i g n a n a l y s i s p r o c e s s i n c l u d i n g ceramic c o m p o s i t e s .

h i g h s t r e s s e s , e t c .

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F i n a l l y , t h e design a n a l y s i s o f h o t s e c t i o n compo- t h r o u g h f o c u s e d r e s e a r c h b u t was sometimes i n t e r d i s c i - n e n t p a r t s , such as combustor l i n e r s o r t u r b i n e vanes p l i n a r y and i n t e g r a t e d .

and b l a d e s , i n v o l v e s t h e use o f a n a l y t i c a l o r empir- Most d i s c i p l i n e s i n t h e HOST P r o j e c t f o l l o w e d a i c a l models. Such models o f t e n a r e p u t i n t o t h e form common approach t o r e s e a r c h . F i r s t , phenomena r e l a t e d o f computer codes f o r p r e d i c t i n g and a n a l y z i n g t h e t o d u r a b i l i t y were i n v e s t i g a t e d , o f t e n u s i n g benchmark a e r o t h e r m a l environment, t h e thermomechanical loads, q u a l i t y e x p e r i m e n t s . W i t h known boundary c o n d i t i o n s and m a t e r i a l and s t r u c t u r a l responses t o such l o a d i n g .

and p r o p e r i n s t r u m e n t a t i o n , t h e s e e x p e r i m e n t s r e s u l t e d When t h e p a r t s a r e exposed t o c y c l i c h i g h temperature i n a c h a r a c t e r i z a t i o n and b e t t e r u n d e r s t a n d i n g o f such o p e r a t i o n as i n a t u r b i n e engine, t h e r e p e t i t i v e phenomena as t h e aerothermal environment, t h e m a t e r i a l s t r a i n i n g o f t h e m a t e r i a l s l e a d s t o c r a c k i n i t i a t i o n and s t r u c t u r a l b e h a v i o r d u r i n g thermomechanical load- and p r o p a g a t i o n u n t i l f a i l u r e o r break-away o c c u r s .

i n g , and c r a c k i n i t i a t i o n and p r o p a g a t i o n . Second, The u s e f u l l i f e o r d u r a b i l i t y o f a p a r t i s u s u a l l y s t a t e - o f - t h e - a r t a n a l y t i c a l models were i d e n t i f i e d , d e f i n e d as t h e number o f m i s s i o n c y c l e s t h a t can be e v a l u a t e d , and t h e n improved by more i n c l u s i v e p h y s i - accumulated b e f o r e i n i t i a t i o n and p r o p a g a t i o n o f s i g - c a l c o n s i d e r a t i o n s a n d l o r more advanced computer code n i f i c a n t c r a c k s . Thus, d e s i g n e r s need t o p r e d i c t development. When no s t a t e - o f - t h e - a r t models e x i s t e d , u s e f u l " l i f e " so t h e y can d e s i g n a p a r t t o meet r e s e a r c h e r s developed new models. f i n a l l y , p r e d i c t i o n s r e q u i r e m e n t s .

u s i n g t h e improved a n a l y t i c a l t o o l s were v a l i d a t e d b y Efforts t o p r e d i c t t h e l i f e o f a p a r t g e n e r a l l y comparison t o e x p e r i m e n t a l r e s u l t s , e s p e c i a l l y t h e follow t h e f l o w o f analyses p o r t r a y e d i n F i g . 1 . I n benchmark q u a l i t y d a t a .

p r a c t i c e , d e s i g n i n g of a p a r t such as a t u r b i n e b l a d e t o meet a s p e c i f i e d l i f e goal may r e q u i r e a number o f Proq r ams i t e r a t i o n s t h r o u g h t h e " L i f e P r e d i c t i o n System" of F u l f i l l m e n t o f t h e HOST P r o i e c t o b i e c t i v e was f i g . 1, v a r y i n g the b l a d e geometry, m a t e r i a l , or c o o l - accompli shed t h r o u g h numerous research"and t e c h n o l o g y i n g e f f e c t i v e n e s s i n each pass, u n t i l a s a t i s f a c t o r y programs. HOST management i s s u e d c o n t r a c t s for 40 sep- l i f e g o a l i s p r e d i c t e d .

a r a t e a c t i v i t i e s w i t h p r i v a t e i n d u s t r y , most o f which A n a l y s i s models and codes have f r e q u e n t l y p r e d i c t e d were m u l t l y e a r and m u l t i p h a s e d . I n s e v e r a l a c t i v i t i e s , p h y s i c a l b e h a v i o r q u a l i t a t i v e l y b u t have e x h i b i t e d more t h a n one c o n t r a c t o r was i n v o l v e d because o f t h e u n a c c e p t a b l e q u a n t i t a t i v e accuracy. To improve p r e d i c - n a t u r e o f t h e r e s e a r c h and each c o n t r a c t o r ' s unique t i v e c a p a b i l i t y , r e s e a r c h e r s g e n e r a l l y need ( 1 ) t o q u a l i f i c a t i o n s . T h i r t e e n more s e p a r a t e a c t i v i t i e s were u n d e r s t a n d and model more a c c u r a t e l y t h e b a s i c p h y s i c s conducted t h r o u g h g r a n t s w i t h u n i v e r s i t i e s . F i n a l l y , o f t h e phenomena r e l a t e d to d u r a b i l i t y , ( 2 ) t o empha- a t t h e NASA Lewis Research C e n t e r , 17 major e f f o r t s s i z e l o c a l as w e l l as g l o b a l c o n d i t i o n s and responses, were s u p p o r t e d b y t h e p r o j e c t . T a b l e I l i s t s a l l t h e ( 3 ) t o accommodate n o n l i n e a r and i n e l a s t i c b e h a v i o r , t e c h n i c a l a c t i v i t i e s conducted i n t h e p r o j e c t .

( 4 ) t o expand some models f r o m two t o t h r e e and

d i mens i o n s . TECHNOLOGY TRANSFER

F o r t u n a t e l y , a t t h e t i m e o f demands f o r improved h o t s e c t i o n d u r a b i l i t y d r a m a t i c i n c r e a s e s were occur- The HOST P r o j e c t r e s e a r c h a c t i v i t i e s were u s u a l l y r i n g i n m a t h e m a t i c a l s o l u t i o n t e c h n i q u e s , e l e c t r o n i c o r g a n i z e d , conducted, and r e p o r t e d a l o n g t h e above computer memory, and computer c o m p u t a t i o n a l speed. d i s c i p l i n e l i n e s . T h i s r e p o r t i s o r g a n i z e d accord- for s i g n i f i c a n t improvements i n ana- The t i m e was r i p e i n g l y and summarizes r e s e a r c h r e s u l t s accomplished i n l y t i c a l p r e d i c t i v e c a p a b i l i t y . t h e p r o j e c t .

Numerous p u b l i c a t i o n s p r o v i d e f u r t h e r d e t a i l s about OVERVIEW OF THE HOST PROJECT r e s e a r c h r e s u l t s f r o m t h e HOST P r o j e c t . S i x annual workshops were conducted w i t h c o n f e r e n c e p r o c e e d i n g s To meet t h e needs f o r improved a n a l y t i c a l d e s i g n ( T u r b i n e Engine Hot S e c t i o n Technology, 1982 t h r o u g h t o o l s , e s p e c i a l l y t h o s e used for and l i f e p r e d i c t i o n 1987) b e i n a D r o v i d e d f o r each one. Each o f t h e Dro- a n a l y s i s o f c y c l i c h i g h t e m p e r a t u r e o p e r a t i o n i n ceedings g e n e r a l l y covers r e s e a r c h r e s u l t s for t h e p r e - advanced combustors and t u r b i n e s , t h e NASA Lewis c e d i n g y e a r . The l a s t two p r o c e e d i n g s a l s o i n c l u d e d a Research C e n t e r sponsored t h e T u r b i n e Engine Hot Sec- b i b l i o g r a p h y o f d e f i n i t i v e r e s e a r c h r e p o r t s . Progress t i o n Technology (HOST) P r o j e c t . The p r o j e c t was i n i t i - i n t h e development o f advanced i n s t r u m e n t a t i o n and i n a t e d i n October 1980 and completed i n l a t e 1987. t h e improvement o f combustor a e r o t h e r m a l and t u r b i n e h e a t t r a n s f e r models was r e p o r t e d by Sokolowski and O b j e c t i v e Ensign (1986). F i n a l l y , a comprehensive b i b l i o g r a p h y The HOST P r o j e c t developed improved a n a l y t i c a l o f t h e HOST P r o j e c t i s b e i n g p r e p a r e d and i s scheduled models f o r t h e a e r o t h e r m a l environment, t h e thermo- f o r p u b l i c a t i o n l a t e r t h i s y e a r ( S o k o l o w s k i , 1988).

mechanical l o a d s , m a t e r i a l b e h a v i o r , s t r u c t u r a l response, and l i f e p r e d i c t i o n , a l o n g w i t h s o p h i s t i - REFERENCES c a t e d computer codes, which can be used i n d e s i g n a n a l y s e s o f c r i t i c a l p a r t s i n advanced t u r b i n e engine Dennis, A.J. and Cruse, T . A . , 1979, "Cost B e n e f i t s More a c c u r a t e a n a l y t i c a l from Improved Hot S e c t i o n L i f e P r e d i c t i o n Technology - combustors and t u r b i n e s .

t o o l s b e t t e r ensure -- d u r i n g t h e d e s i g n process --

f o r A i r c r a f t Engine Combustor and T u r b i n e P a r t s , " A I A A improved d u r a b i l i t y of f u t u r e h o t s e c t i o n engine Paper 79-1 154.

components.

Sokolowski, D.E. and Ensign, C . R . , 1986, "Toward Approach Improved D u r a b i l i t y i n Advanced Combustors and A d d r e s s i n q t h e complex d u r a b i l i t y p r o b l e m i n h i g h Turbines -- Progress i n t h e P r e d i c t i o n o f t e m p e r a t u r e c y c l i c a l l y ' o p e r a t e d t u r b j n e e n g i n e compo- Thermomechanical Loads", NASA TM-88932.

n e n t s r e q u i r e s r e s e a r c h e f f o r t s i n numerous t e c h n i c a l I n t h e HOST P r o j e c t s i x d i s c i p l i n e s were d i s c i p l i n e s . Sokolowski, D.E., 1988, "Comprehensive B i b l i o g r a p h y o f i n v o l v e d : i n s t r u m e n t a t i o n , combustion, t u r b i n e h e a t t h e T u r b i n e Engine Hot S e c t i o n Technology (HOST) t r a n s f e r , s t r u c t u r a l a n a l y s i s , f a t i g u e and f r a c t u r e , P r o j e c t , " NASA TM-100275, t o be p u b l i s h e d .

T h i s i n v o l v e m e n t was n o t o n l y and s u r f a c e p r o t e c t i o n .

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Stephans, J.R., 1982, "COSAM Program Overview." COSAM T u r b i n e Enqine H o t S e c t i o n Technoloqy (HOST) 1984, ( C o n s e r v a t i o n of S t r a t e g i c Aerospace M a t e r i a l s , Program NASA CP-2339.

Overview, NASA TM-83006, p p . 1 - 1 1 .

T u r b i n e Enqine Hot S e c t i o n Technology (HOST) 1985.

T a n r i k u t , S . , M a r s h a l l , R.L.. and Sokolowski, D . E . , NASA CP-2405.

1981, "Improved Combustor D u r a b i l i t y - Segmented

Approach w i t h Advanced C o o l i n g Techniques," AIAA Paper T u r b i n e Enqine Hot S e c t i o n Technology (HOST) 1986, 81 - 1 354. NASA CP-2444.

T u r b i n e Engine Hot S e c t i o n Technology (HOST) 1982, T u r b i n e Engine Hot S e c t i o n Technoloqy (HOST) 1987.

NASA TM-83022. NASA CP-2493.

T u r b i n e Enqine Hot S e c t i o n Technoloqy (HOST) 1983, NASA CP-2289.

MATERIALS MATERIALS BEHAVIOR CRITERIA - FIGURE 1. INTEGRATION OF ANALYSES LEADS TO LIFE PREDICTION OF HOT SECTION PARTS,

TABLE I . . HOST P r o j e c t A c t i v i t i e s

C o n t r a c t ( C ) . Grant (G). o r

I n s t r u m e n t a t i o r r . . NASA O r g a n i z a t i o n ( N ) Number

H o t S e c t i o n Viewing System . . . . . . . . . . . . . . . . . . . . . . . . . . . NAS3-23156 C Dynamic Gas Temperature Measurement System . A . . . . . . . . . . . . . . . . .

C NAS3-23154 Dynamic Gas Temperature Measurement System . B . . . . . . . . . . . . . . . . .

C NAS3-24228 T u r b i n e S t a t i c S t r a i n Gage . A . . . . . . . . . . . . . . . . . . . . . . . . .

C NAS3-23169 T u r b i n e S t a t i c S t r a i n Gage . B . . . . . . . . . . . . . . . . . . . . . . . . .

C NAS3-23722 T u r b i n e Heat F l u x Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . .

C NAS3-23529 L a s e r Speckle S t r a i n Measurement . . . . . . . . . . . . . . . . . . . . . . . . C NAS3-26615 H i g h Temperature S t r a i n Gage M a t e r i a l s . . . . . . . . . . . . . . . . . . . . .

NAG3 -501 H o t S e c t i o n Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2510 Laser Anemometry f o r Hot S e c t i o n A p p l i c a t i o n s . . . . . . . . . . . . . . . . .

2520/2530 HOST I n s t r u m e n t A p p l i c a t i o n s . . . . . . . . . . . . . . . . . . . . . . . . . . 2510 Combustion . I . . . . . . . . . . . . . . . . .

Assessment o f Combustor Aerothermal Models na53 -23523 C Assessment o f Combustor Aerothermal Models . I 1 . . . . . . . . . . . . . . . . NAS3-23524 C Assessment o f Combustor Aerothermal Models . I 1 1 . . . . . . . . . . . . . . . . NAS3-23525 C Improved Numerical Methods . I . . . . . . . . . . . . . . . . . . . . . . . . . na53 -243 51 C Improved Numerical Methods . I 1 . . . . . . . . . . . . . . . . . . . . . . . .

C NAS3-24350 Improved Numerical Methods . 111 . . . . . . . . . . .

. . . . . . . . . . . . . NAG3-596 G

Flow I n t e r a c t i o n Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . C NAS3-24350 F u e l S w i r l C h a r a c t e r i z a t i o n . I . . . . . . . . . . . . . . . . . . . . . . . . C NAS3-24350 Fuel S w i r l C h a r a c t e r i z a t i o n . I 1 . . . . . . . . . . . . . . . . . . . . . . . . NAS3-24352 C Mass and Momenta T r a n s f e r . . . . . . . . . . . . . . . . . . . . . . . . . . .

C NAS3-227 71 Oiffuser/Combustor I n t e r a c t i o n . . . . . . . . . . . . . . . . . . . . . . . . .

C F33615-84-C-2427 D i l u t i o n J e t M i x i n g S t u d i e s . . . . . . . . . . . . . . . . . . . . . . . . . .

C NAS3-22110 L a t e r a l J e t I n j e c t i o n i n t o T y p i c a l Combustor F l o w f i e l d s . . . . . . . . . . . . G NAG3-549 Flame R a d i a t i o n S t u d i e s . . . . . . . . . . . . . . . . . . . . . . . . . . . .

N 2650 T u r b i n e Heat T r a n s f e r Mainstream Turbulence I n f l u e n c e on Flow i n a T u r n i n g Duct . A . . . . . . . . . C NAS3-23278 . B Mainstream Turbulence I n f l u e n c e on Flow i n a T u r n i n q Duct . . . . . . . . . G NAG3-617 2-0 Heat T r a n s f e r w i t h o u t F i l m C o o l i n g . . . . . . . . . . . . . . . . . . . . . NAS3-22761 2-0 Heat T r a n s f e r w i t h Leading Edge F i l m C o o l i n g . . . . . . . . . . . . . . . .

NAS3-23695 2-D Heat T r a n s f e r w i t h Downstream F i l m C o o l i n g . . . . . . . . . . . . . . . . . NAS3-24615 Measurement o f Blade and Vane Heat T r a n s f e r C o e f f i c i e n t i n a T u r b i n e R o t o r . . . NAS3-23717 Assessment o f 3-0 Boundary L a y e r Code . . . . . . . . . . . . . . . . . . . . . NAS3-23716 Coolant S i d e Heat T r a n s f e r w i t h R o t a t i o n . . . . . . . . . . . . . . . . . . . . C NAS3-23691 C A n a l y t i c Flow and Heat T r a n s f e r . . . . . . . . . . . . . . . . . . . . . . . . NAS3-24358 E f f e c t s o f Turbulence on Heat T r a n s f e r . . . . . . . . . . . . . . . . . . . . . G NAG3-522 T i p Region Heat T r a n s f e r . . . . . . . . . . . . . . . . . . . . . . . . . . . . NAG3 -623 Impingement C o o l i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . n5g3 -075 Computation o f T u r b i n e B l a d e Heat T r a n s f e r . . . . . . . . . . . . . . . . . . . NAG3-579 Advanced I n s t r u m e n t a t i o n Development . . . . . . . . . . . . . . . . . . . . . . 2640 Warm T u r b i n e Flow Mapping w i t h Laser Anemometry . . . . . . . . . . . . . . . . 2620 Real Engine-Type T u r b i n e Aerothermal T e s t i n g . . . . . . . . . . . . . . . . . . 2640 S t r u c t u r a l A n a l y s i s f h e r m a l / S t r u c t u r a l Load T r a n s f e r Code . . . . . . . . . . . . . . . . . . . . . C NAS3-23272 C 3-0 I n e l a s t i c A n a l y s i s Methods . I . . . . . . . . . . . . . . . . . . . . . . . NAS3-23697 C 3-D I n e l a s t i c A n a l y s i s Methods . I1 . . . . . . . . . . . . . . . . . . . . . . NAS3-23698 Component S p e c i f i c M o d e l i n g . . . . . . . . . . . . . . . . . . . . . . . . . . NAS3-23687 L i n e r C y c l i c L i f e D e t e r m i n a t i o n . . . . . . . . . . . . . . . . . . . . . . . . 5210 S t r u c t u r a l Components Response Program . . . . . . . . . . . . . . . . . . . . . 5210 H i g h Temperature S t r u c t u r e s Research L a b o r a t o r y . . . . . . . . . . . . . . . .

C o n s t i t u t i v e Model Development . . . . . . . . . . . . . . . . . . . . . . . . . 5210 C o n s t i t u t i v e M o d e l i n g f o r I s o t r o p i c M a t e r i a l s . I . . . . . . . . . . . . . . . NAS3-23925 C o n s t i t u t i v e M o d e l i n g f o r I s o t r o p i c M a t e r i a l s . I1 . . . . . . . . . . . . . . . C NAS3-23927 T h e o r e t i c a l C o n s t i t u t i v e Hoaels f o r S i n g l e C r y s t a l A l l o y s . . . . . . . . . . . G NAG3-5 11 G NAG3 -51 2 B i a x i a l C o n s t i t u t i v e E q u a t i o n Development f o r S i n g l e C r y s t a l s and D i r e c t i o n a l l y S o l i d i f i e d A l l o y s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

F a t i g u e and F r a c t u r e Creel)-Fatique L i f e P r e d i c t i o n f o r I s o t r o p i c M a t e r i a l s . . . . . . . . . . . . . C NAS3-23288 C NAS3-23940 E l e v a t e d Temperature Crack P r o p a g a t i o n . . . . . . . . . . . . . . . . . . . .

C NAS3-23939 L i f e P r e d i c t i o n and M a t e r i a l C o n s t i t u t i v e Behavior f o r A n i s o t r o p i c M a t e r i a l s . .

A n a l y s i s o f F a t i g u e Crack Growth Mechanism . . . . . . . . . . . . . . . . . . . G NAG3-348

. . . . . . . N

V i t a l i z a t i o n o f H i g h Temperature F a t i g u e and S t r u c t u r e s L a b o r a t o r y 5220 S u r f ace P r o t e c t i o n

. . . . . . . . . . . . . . . . . C

E f f e c t s o f S u r f a c e C h e m i s t r y on Hot C o r r o s i o n NAS3-23926 Thermal B a r r i e r C o a t i n g L i f e P r e d i c t i o n . I . . . . . . . . . . . . . . . . . . C NAS3-23943 Thermal B a r r i e r C o a t i n g L i f e P r e d i c t i o n . I1 . . . . . . . . . . . . . . . . . . C NAS3-23944 C NAS3-23945 Thermal B a r r i e r Coating L i f e P r e d i c t i o n . 111 . . . . . . . . . . . . . . . . .

NAG3-201 A i r f o i l D e p o s i t i o n Model . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mechanical Behavior o f Thermal B a r r i e r Coatings . . . . . . . . . . . . . . . . NCC3-27 C o a t i n g O x i d a t i o n / D i f f u s i o n P r e d i c t i o n . . . . . . . . . . . . . . . . . . . . . 5160 D e p o s i t i o n Model V e r i f i c a t i o n . . . . . . . . . . . . . . . . . . . . . . . . . 5160 Dual C y c l e A t t a c k . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Rig/Engine C o r r e l a t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Burner R i g M o d e r n i z a t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5160 Notes: A. B A c t i v i t i e s i n s e r i e s

I . 11. 111 A c t i v i t i e s i n p a r a l l e l

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ADVANCED HIGH TEMPERATURE INSTRUMENTATION FOR HOT SECTION RESEARCH APPLICATIONS D. R. Englund and R. G. Searholtz National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio ( 5 ) Development o f h i g h temperature s t r a i n measur- ABSTRACT i n g systems.

I n a d d i t i o n t o t h i s , a major e f f o r t was s t a r t e d Programs t o develop r e s e a r c h i n s t r u m e n t a t i o n f o r s t a r t o f HOST t o develop t h i n f i l m j u s t p r i o r t o t h e use i n t u r b i n e engine h o t s e c t i o n s a r e d e s c r i b e d .

sensors f o r a p p l i c a t i o n s i n h o t s e c t i o n s , p a r t i c u l a r l y These programs were i n i t i a t e d t o p r o v i d e improved mea- f o r t h e measurement o f t u r b i n e a i r f o i l s u r f a c e tempera- f o r a m u l t i d i s c i p l i - surements c a p a b i l i t y as s u p p o r t t u r e .

n a r y e f f o r t t o e s t a b l i s h t e c h n o l o g y l e a d i n g t o T h i s paper w i l l d e s c r i b e t h e s t a t e o f development improved hot s e c t i o n d u r a b i l i t y . S p e c i f i c measurement o f these sensors and measuring systems and, i n some systems d e s c r i b e d h e r e i n c l u d e h e a t f l u x sensors, a cases, w i l l show examples o f measurements made w i t h dynamic gas t e m p e r a t u r e measuring systems, l a s e r ane- t h i s new i n s t r u m e n t a t i o n . The work d e s c r i b e d was done mometry for h o t s e c t i o n a p p l i c a t i o n s , an o p t i c a l sys- i n t e r i o r o f a combustor d u r i n g a t t h e NASA Lewis Research Center and a t v a r i o u s con- tem f o r v i e w i n g t h e t r a c t and g r a n t f a c i l i t i e s .

o p e r a t i o n . t h l n f i l m sensors f o r surface t e m p e r a t u r e and s t r a i n measurements, and h i g h t e m p e r a t u r e s t r a i n HEAT FLUX SENSORS measuring systems. The paper w i l l d e s c r i b e t h e s t a t e o f development of t h e s e sensors and measuring systems One o f t h e i m p o r t a n t e n v i r o n m e n t a l parameters i n and, i n some cases, w i l l show examples o f measurements t h e h o t s e c t i o n i s h e a t f l u x . The h e a t f l u x i s one o f made w i t h t h i s i n s t r u m e n t a t i o n . The paper covers work t h e v a r i a b l e s i n t h e h e a t b a l a n c e e q u a t i o n which e s t a b - done a t t h e NASA Lewis Research Center and a t v a r l o u s l i s h e s t h e c o o l i n g r e q u i r e m e n t s and t h e a n t i c i p a t e d c o n t r a c t and g r a n t f a c i l i t i e s .

There s u r f a c e t e m p e r a t u r e o f a h o t s e c t i o n component.

i s n o t s u f f i c i e n t knowledge o f h e a t t r a n s f e r c o e f f i - INTRODUCTION c i e n t s under engine o p e r a t i n g c o n d i t i o n t o p e r m i t p r e - d i c t i o n o f s u r f a c e temperatures t o w i t h i n a c c e p t a b l e The T u r b i n e Engine.Hot S e c t i o n Technology (HOST) a c c u r a c y . T h i s i s e s p e c i a l l y t r u e as h e a t f l u x e s Program was s t a r t e d by NASA i n t h e l a t e 1970's i n approach 1 MW/m2. I n i t i a l work was d i r e c t e d a t d e v e l - o r d e r t o d e v e l o p t e c h n o l o g y l e a d i n g to improved h o t f o r use i n combustor l i n e r s ( A t k i n s o n o p i n g sensors s e c t i o n d u r a b i l i t y . The program was a m u l t i d i s c i p l i - e t a l . , 1983; A t k i n s o n and S t r a n g e , 1982; A t k i n s o n n a r y e f f o r t i n v o l v i n g s t r u c t u r e s , surface p r o t e c t i o n , e t a l . , 1985a). I n l a t e r work sensors were mounted f a t i g u e , combustion, h e a t t r a n s f e r , and i n s t r u m e n t a - i n t o a i r c o o l e d b l a d e s and vanes ( A t k i n s o n e t a l . , t i o n . The o b j e c t i v e o f t h e i n s t r u m e n t a t i o n p o r t i o n o f 1984; A t k i n s o n e t a l . . 1985b).

t h e program was t o d e v e l o p improved measurements capa- Sensor d e s i g n s f o l l o w e d c o n v e n t i o n a l concepts i n b i l i t y t o measure t h e environment w i t h i n t h e h o t t o h e a t which t h e t e m p e r a t u r e d i f f e r e n c e p r o p o r t i o n a l s e c t i o n and measure t h e response o f h o t s e c t i o n compo- c o n d u c t i o n t h r o u g h t h e sensor body i s measured. D i f - n e n t s t o t h a t imposed environment. I n s t r u m e n t develop- f e r e n t i a l thermocouples u s i n g t h e sensor body m a t e r i a l ment programs t h a t r e s u l t e d i n c l u d e d t h e f o l l o w i n g : as p a r t o f t h e c i r c u i t were used t o measure t h e temper- ( 1 ) Development of sensors f o r measuring t h e h e a t a t u r e d i f f e r e n c e s . C a l i b r a t i o n s (Holanda, 1984) were f l u x on combustor l i n e r s and t u r b i n e a i r f o i l s .

made o f t h e t h e r m o e l e c t r i c p o t e n t i a l o f a number o f ( 2 ) Development of a system t o measure t h e f l u c t u - e n g i n e e r i n g a l l o y s and t h e s e e s t a b l i s h e d t h e v a l i d i t y a t i n g component of combustor e x i t temperature w i t h a o f t h i s approach, which c o n s i d e r a b l y s i m p l i f i e d f a b r i - f r e q u e n c y response t o 1000 Hz.

c a t i o n .

( 3 ) Development o f l a s e r anemometer t e c h n i q u e s for F i g u r e s 1 and 2 show t h e sensors t h a t were d e v e l - a p p l i c a t i o n s i n h o t s e c t i o n s .

oped for combustor l i n e r s . The sensor i s b u i l t i n t o a ( 4 ) Development o f an o p t i c a l system f o r v i e w t n g H a s t e l l o y X d i s k 0 . 8 cm i n d i a m e t e r and t h e same t h i c k - t h e i n t e r i o r o f a combustor d u r i n g o p e r a t i o n .

ness as t h e l i n e r . A f t e r c a l i b r a t i o n o f t h e sensor ORIGINAL PAGE IS:

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t h e d i s k i s welded i n t o a h o l e c u t i n t h e l i n e r . F i g - was t h e t y p e w i t h l o u v e r l i p s and b l e e d h o l e s t o pro- u r e 1 shows t h e embedded thermocouple sensor. The v i d e f i l m c o o l i n g o f t h e h o t s i d e s u r f a c e . The d a t a o f d i s k i s grooved so t h a t 0 . 2 5 mm o u t s i d e d i a m e t e r F i g . 5 i n d i c a t e t h a t t h e r e i s s i g n i f i c a n t c o n v e c t i v e sheathed, s i n g l e c o n d u c t o r thermocouple w i r e can be c o o l i n g o f t h e h o t s i d e s u r f a c e of t h e combustor.

l a i d i n t o t h e grooves and covered w i t h weld m a t e r i a l . Test r e s u l t s f r o m sensors mounted i n t u r b i n e a i r - The thermocouple w i r e s a r e I S A Type K . Chromel-Alumel, f o i l s i n d i c a t e t h a t these sensors a r e s u f f i c i e n t l y l e a d s a r e used so as t o m a i n t a i n and s i n g l e c o n d u c t o r s e n s i t i v e t o t r a n s v e r s e g r a d i e n t s i n h e a t f l u x and tem- good i n s u l a t i o n r e s i s t a n c e between t h e w i r e and t h e p e r a t u r e t h a t a p p l i c a t i o n s i n blades and vanes must be e x t e r n a l m e t a l ;heath. Grounded Alumel j u n c t i o n s a r e c a r e f u l l y e v a l u a t e d . The g r e a t e r c o m p l e x i t y o f t h e l o c a t e d on t h e h o t and c o l d s i d e o f t h e sensor body a i r f o i l s ( e . q . , h i g h s u r f a c e c u r v a t u r e and c o o l i n g pas- and a Chromel j u n c t i o n i s added t o t h e c o l d s i d e . A sage s t r u c t u r e ) causes more severe g r a d i e n t s than were v o l t a g e measurement between t h e Alumel l e a d w i r e s ( i . e . , encountered i n combustor l i n e r s . S e n s i t i v i t y t o t r a n s - u s i n g t h e A l u m e l - H a s t e l l o y X-Alumel d i f f e r e n t i a l t h e r - verse g r a d i e n t s i s e s p e c i a l l y apparent i n the Gardon mocouple) p r o v i d e s t h e h o t - t o - c o l d s i d e t e m p e r a t u r e gage sensor because o f i t s l a c k o f symmetry.

d i f f e r e n c e p r o p o r t i o n a l to t h e one-dimensional h e a t f l o w t h r o u g h t h e sensor body a t t h a t p o i n t . A measure- DYNAMIC GAS TEMPERATURE MEASURING SYSTEM ment u s i n g t h e c o n v e n t i o n a l Chromel-Alumel thermocou- p l e p r o v i d e s t h e c o l d s i d e temperature o f t h e sensor. Another i m p o r t a n t e n v i r o n m e n t a l parameter i n t h e F i g u r e 2 shows a Gardon Gage sensor. I n t h i s case h o t s e c t i o n o f a t u r b i n e engine i s t h e gas temperature.

t h e sensor body has a 1 . 5 mm d i a m e t e r c y l i n d r i c a l I n g e n e r a l , most a t t e n t i o n has been d i r e c t e d a t t h e c a v i t y on t h e c o l d s i d e so t h a t a t h i n membrane of time-average v a l u e o f gas temperature r a t h e r than t h e m a t e r i a l i s l e f t on t h e h o t s i d e . Alumel w i r e s a r e f l u c t u a t i n g component o f gas temperature. It i s gener- p o s i t i o n e d so t h e j u n c t i o n s a r e formed w i t h t h e a l l y agreed t h a t t h e r e may be s i g n i f i c a n t temperature f l u c t u a t i o n i n t h e gas e x i t i n g a combustor due t o H a s t e l l o y X a t t h e c e n t e r o f t h e membrane and h a l f w a y u p t h e s i d e w a l l o f t h e c a v i t y . A Chromel w i r e j u n c t i o n i n c o m p l e t e m i x i n g of t h e combustion and d i l u t i o n gas i s a l s o made on t h e s i d e w a l l of t h e c a v i t y . A f t e r t h e streams. I t i s a l s o agreed t h a t thermal c y c l i n g o f thermocouples a r e i n s t a l l e d , t h e c a v i t y i s f i l l e d w i t h t h e s u r f a c e s o f t u r b i n e a i r f o i l s can r e s u l t i n s p a l l - ceramic cement. i n g o f o x i d e f i l m s used f o r c o r r o s i o n p r o j e c t i o n and Sensors o f t h e embedded thermocouple and Gardon thus s h o r t e n t h e l i f e o f t h e a i r f o i l s . Development o f Gage t y p e s have a l s o been b u i l t i n t o a i r c o o l e d b l a d e s a system to measure gas temperature f l u c t u a t i o n s was and vanes. I n t h e case o f t u r b i n e b l a d e s , two-piece undertaken t o a i d i n modeling combustor flow and i n b l a d e s were used and t h e sensors were i n s t a l l e d from s t u d y i n g t h e thermal c y c l i n g of a i r f o i l s u r f a c e s . Com- t h e c o o l i n g passage s i d e o f t h e b l a d e . The two b l a d e b u s t o r m o d e l i n g r e q u i r e m e n t s s e t t h e f r e q u e n c y response h a l v e s were t h e n j o i n e d by b r a z i n g . I n t h e case o f goal a t 1000 Hz.

vanes, s e c t i o n s o f t h e vane w a l l o p p o s i t e t o t h e The approach used i n t h i s work was t o d e v i s e a way d e s i r e d sensor s i t e s were removed and t h e sensors were t o d e t e r m i n e i n s i t u t h e compensation spectrum r e q u i r e d i n s t a l l e d t h r o u g h these "windows." F i g u r e 3 d e p i c t s t o c o r r e c t for t h e l i m i t e d f r e q u e n c y response o f a t h e i n s t a l l a t i o n process on a t u r b i n e vane.

thermocouple probe l o c a t e d i n t h e gas stream. Fre- The h e a t f l u x sensors were c a l i b r a t e d o v e r a h e a t quency compensation has o f t e n been used, e s p e c i a l l y f l u x range up t o 1.7 MW/m2 and a t e m p e r a t u r e range t o w i t h hot w i r e anemometers, i n t h e measurement o f 1250 K . The c a l i b r a t i o n s were accomplished by impos- dynamic flow phenomena. The problem w i t h t h i s tech- i n g a known r a d i a n t h e a t f l u x on t h e h o t s i d e s u r f a c e n i q u e when a p p l i e d t o a thermal element i n a flow o f t h e sensor and f l o w i n g c o o l i n g a i r o v e r t h e c o l d stream i s t h a t t h e r e q u i r e d compensation spectrum i s a s i d e s u r f a c e . The h o t s i d e s u r f a c e was coated w i t h a f u n c t i o n o f b o t h t h e thermal mass o f t h e thermocouple h i g h t e m p e r a t u r e b l a c k p a i n t w i t h a measured absorp- and t h e c o e f f i c i e n t for h e a t t r a n s f e r between t h e gas tance and e m i t t a n c e o f 0.89 o v e r t h e t e s t temperature and t h e thermocouple. T h i s h e a t t r a n s f e r c o e f f i c i e n t r a n g e . I n a l l cases t h e r e f e r e n c e temperature was mea- i s a f u n c t i o n o f t h e gas flow c o n d i t i o n s . Each t i m e s u r e d and used t o e s t i m a t e t h e h o t s i d e s u r f a c e temper- t h e flow c o n d i t i o n s change, t h e compensation spectrum a t u r e so t h a t energy b e i n g r a d i a t e d away from t h e h o t must be r e d e t e r m i n e d . I n some cases e s t i m a t e s o f t h e s u r f a c e c o u l d be c a l c u l a t e d and t a k e n i n t o account. compensation spectrum may be s u f f i c i e n t ; i n t h i s case E s t i m a t e s o f t h e c o n v e c t i v e h e a t flow f r o m t h e h o t s u r - i t was i m p o r t a n t to be a b l e t o make i n s i t u determina- f a c e were a l s o made and used i n t h e h e a t b a l a n c e . t i o n s o f t h e compensation spectrum.

The h e a t f l u x sensor c a l i b r a t i o n systems used banks The system t h a t was developed (Elmore e t a l . , 1984; o f t u n g s t e n f i l a m e n t lamps e n c l o s e d i n q u a r t z tubes as Elmore e t a l . , 1983; Elmore e t a l . , 1986a and b; Stocks h e a t f l u x sources; t h e most p o w e r f u l o f these systems and Elmore. 1986) uses a dual element thermocouple p r o v i d e d h e a t f l u x e s up t o 1 . 7 MW/m2. The q u a r t z lamp probe such as shown i n F i g . 6. Thermocouples a r e r i g s were c a p a b l e o f l o n g t i m e and c y c l i c o p e r a t i o n a t formed w i t h c a r e f u l l y b u t t welded j u n c t i o n s so t h a t reduced h e a t f l u x e s . Thermal c y c l i n g and d r i f t t e s t s t h e r e i s n o v a r i a t i o n i n diameter i n t h e r e g i o n o f t h e were r u n on these sensors u s i n g t h i s c a p a b i l i t y . j u n c t i o n . These thermocouples a r e each supported C a l i b r a t i o n and performance t e s t s on h e a t f l u x sen- across a p a i r o f s u p p o r t p o s t s so t h a t t h e y a r e p a r a l - sors have i n d i c a t e d t h a t measurements can be a c h i e v e d l e l c y l i n d e r s i n c r o s s f l o w and a r e i n c l o s e enough f a i r l y r e a d i l y on combustor l i n e r s , b u t t h a t a c c u r a t e p r o x i m i t y tapprox 1 mm) so t h a t t h e y a r e measuring t h e measurements on a i r f o i l s a r e d i f f i c u l t t o a c h i e v e . same t e m p e r a t u r e . The thermocouple w i r e s and t h e sup- Combustor l i n e r measurements have been made b o t h a t a p o r t p o s t s a r e made f r o m Pt-30RhIPt-6Rh. The thermo- c o n t r a c t o r f a c i l i t y and a t NASA Lewis u s i n g sensors c o u p l e j u n c t i o n s a r e midway between t h e s u p p o r t p o s t s .

whose c a l i b r a t i o n u n c e r t a i n t y i s w i t h l n 4 p e r c e n t of The two thermocouples have d i f f e r e n t d i a m e t e r s , com- a nominal f u l l s c a l e h e a t f l u x o f 1 MW/m2. F i g u r e 4 monly 75 and 250 pm. N e i t h e r o f these thermocouples shows an i n s t r u m e n t e d combustor l i n e r segment. have t h e d e s i r e d f r e q u e n c y response, b u t a comparison F i g u r e 5 compares measured v a l u e s o f h e a t f l u x con- o f t h e i r dynamic s i g n a l s can l e a d t o t h e needed compen- d u c t e d t h r o u g h a combustor l i n e r and r a d i a n t f l u x i n c i - s a t i o n spectrum. The technique i s based on t h e use o f d e n t on t h e l \ n e r a t d i f f e r e n t combustor p r e s s u r e t h e r a t i o o f t h e F o u r i e r c o e f f i c i e n t s o f t h e dynamic l e v e l s . The r a d i a n t h e a t f l u x was measured w i t h a com- s i g n a l s f o r f r e q u e n c i e s i n t h e range where t h e s i g n a l s m e r c i a l r a d i o m e t e r . The combustor l i n e r i n t h i s t e s t

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become a t t e n u a t e d . I n t h e svstem which has been deve- u s i n g t h e w a l l b i - d i r e c t i o n a l r e f l e c t a n c e d i s t r i b u t i o n loped, t h e s i g n a l s a r e r e c o r d e d on magnetic tape and f u n c t i o n (8RDF) and t h e i r r a d i a n c e o f t h e i n c i d e n t processed i n a g e n e r a l purpose d i g i t a l computer a t a A p r o c e d u r e was developed t o f i n d t h e optimum beams.

l a t e r t i m e . The d a t a r e d u c t i o n process takes a p p r o x i a p e r t u r e s t o p shape for t h e probe volume l o c a t e d a S N R as a m a t e l y 5 min f o r each f l o w c o n d i t i o n f o r which a new g i v e n d i s t a n c e f r o m a w a l l . F i g u r e 8 shows compensation spectrum must be c a l c u l a t e d . f u n c t i o n o f probe volume t o w a l l d i s t a n c e f o r two o p t i - Elmore e t a l . (1986 a and b ) d e s c r i b e experiments c a l systems w i t h optimum a p e r t u r e masks.

t o demonstrate t h e f r e q u e n c y response o f t h e system. The 8RDF was measured f o r a number o f uncoated Measurements were made i n a s p e c i a l l y designed t e s t r m a t e r i a l s , f i n i s h e s , and s u r f a c e c o a t i n g . Data were and i n t h e e x h a u s t o f an a t m o s p h e r i c b u r n e r . Compari o b t a i n e d f o r "as machined" s u r f a c e s , p o l i shed s u r - sons were made between t h e dynamic gas temperature sy f a c e s , g l o s s y b l a c k c o a t i n g s , and f l a t back c o a t i n g s .

tem and v e r y f i n e w i r e r e s i s t a n c e thermometers ( 6 and Based on these d a t a , t h e b e s t s u r f a c e f o r LA a p p l i c a - 12 u m w i r e d i a m e t e r s ) . A t low f r e a u e n c i e s (below t i o n s appears t o be a g l o s s y b l a c k c o a t i n g . A l t h o u g h 250' Hz) w i t h r e a s o n a b l e t e m p e r a t u r e f l u c t u a t i o n s agree- a b l a c k g l o s s y s u r f a c e has a r e l a t i v e l y l a r g e s p e c u l a r ments w i t h i n *23 p e r c e n t were o b t a i n e d . Poorer r e s u l t s r e f l e c t i o n , t h e d i f f u s e l y r e f l e c t e d l i g h t , which i s were o b t a i n e d a t h i g h e r f r e q u e n c i e s b u t h e r e t h e tem- u s u a l l y o f g r e a t e s t concern i n LA systems, i s substan- p e r a t u r e f l u c t u a t i o n s were so small as t o make t h e d a t a t i a l l y l e s s t h a n t h e d i f f u s e l y r e f l e c t e d l i g h t f r o m a q u e s t i o n a b l e . f l a t b l a c k c o a t i n g .

T h i s system has been used to measure f l u c t u a t i n g t e m p e r a t u r e i n b o t h t u r b i n e engines and i n combustor Seedi n q t e s t r i g s . A sample o f d a t a f r o m a t u r b i n e e n g i n e P a r t i c l e c h a r a c t e r i s t i c s necessary f o r h o t s e c t i o n t e s t i s shown i n F i g . 7. I n t h i s t e s t t h e probe was LA a r e p r i m a r i l y t h e same as low t e m p e r a t u r e LA, w i t h l o c a t e d between f i r s t - s t a g e t u r b i n e vanes. For t h e t h e e x c e p t i o n t h a t t h e p a r t i c l e s must r e t a i n those d a t a shown i n F i g . 7 , t h e engine was o p e r a t i n g a t an c h a r a c t e r i s t i c s a t h i g h t e m p e r a t u r e s . Based on a i n t e r m e d i a t e power l e v e l and t h e average gas tempera- survey o f a v a i l a b l e m a t e r i a l s , a p a r t i c u l a r grade of t u r e was 1200 K. F i g u r e 7 shows f o u r p l o t s o f f l u c t u - aluminum o x i d e (nominal 1 pm d i a d was s e l e c t e d . A a t i n g t e m p e r a t u r e v e r s u s t i m e . F i g u r e s 7(a) and ( b ) commercial, high-volume f l u i d i z e d bed was chosen t o shown t h e uncompensated s i g n a l s f r o m t h e 75 and 250 p m d i s p e r s e t h e seed p a r t i c l e s .

thermocouples. Note t h a t t h e temperature s c a l e s on An e x p e r i m e n t was a l s o conducted t o d e t e r m i n e t h e these p l o t s have been a d j u s t e d so as t o show t h e wave- f e a s i b i l i t y o f u s i n g c h e m i c a l l y formed seed for h o t f o r m s . A l s o n o t e t h a t t h e r m s temperature f l u c t u a t i o n f l o w s . T i t a n i u m t e t r a c h l o r i d e vapor was i n j e c t e d i n t o i s l i s t e d on each p l o t . F i g u r e 7 ( c ) shows t h e compen- t h e f l o w where i t r e a c t e d w i t h t h e w a t e r vapor t o form s a t e d t e m p e r a t u r e f l u c t u a t i o n f r o m t h e 75 p m thermocou- t i t a n i u m d i o x i d e and h y d r o c h l o r i c a c i d ( H C l ) . The p l e , and F i g . 7(d) show an expanded t i m e segment o f t i t a n i u m d i o x i d e i s a s u i t a b l e h i g h t e m p e r a t u r e seed t h e compensated s i g n a l . The rms v a l u e o f t h e compen- m a t e r i a l ; i t has a sub-micron s i z e , and i t i s produced s a t e d t e m p e r a t u r e f l u c t u a t i o n i s 218 K and t h e peak- i n l a r g e q u a n t i t i e s . However, t h e H C I , i f n o t n e u t r a l - to-peak f l u c t u a t i o n i s a p p r o x i m a t e l y 2500 K. i z e d , can cause c o r r o s i o n , which l i m i t s t h e a p p l i c a - t i o n o f t h i s seeding t e c h n i q u e .

LASER ANEMOMETRY Preprocessor f o r Frlnge-Type LA The l a s e r anemometer (LA) has become a v a l u a b l e The q u a l i t y o f d a t a from an LA i s c r i t i c a l l y tool i n t u r b i n e e n g i n e r e s e a r c h , p r o v i d i n g d a t a t h a t deoendent on a number o f c o n t r o l s e t t i n s s of t h e S i S - would be almost i m p o s s i b l e t o g a t h e r u s i n g conven- n a i p r o c e s s o r . These t y p i c a l l y i n c l u d e - t h e o p t i c a l - t i o n a l i n s t r u m e n t a t i o n . However, t h e use o f LA i n t u r - d e t e c t i o n system g a i n ( d e t e r m i n e d by t h e p h o t o m u l t i - bomachinery has p r o v e n t o be one o f i t s m r e d i f f i c u l t p l i e r tube h i g h v o l t a g e and a m p l i f i e r g a i n ) and t h e a p p l i c a t i o n s . Turbomachinery components a r e t y p i f i e d e l e c t r i c a l f i l t e r s used t o remove t h e low f r e q u e n c y by s m a l l passages and h i g h l y a c c e l e r a t e d , h i g h - v e l o c i t y t o reduce s h o t n o i s e . A s t u d y p e d e s t a l component and f l o w s . T h i s l e a d s t o t h e need f o r small seed p a r t i c l e s of f i l t e r s on measure- was made t o q u a n t i f y t h e e f f e c t w i l l f a i t h f u l l y f o l l o w t h e f l o w . U n f o r t u n a t e l y , t h a t ment accuracy ( O b e r l e and S e a s h o l t z , 1985). Several common f i l t e r d e s i g n s were examined. I t was shown small p a r t i c l e s a r e weak l i g h t s c a t t e r e r s , which r e s u l t i n low s i g n a l l e v e l s . I n a d d i t i o n , measurements i n t h a t b o t h t h e f i l t e r t y p e and t h e c u t o f f f r e q u e n c i e s small passages r e q u i r e g r e a t c a r e i n t h e d e s i g n of t h e must be c a r e f u l l y s e l e c t e d t o a v o i d f i l t e r - i n d u c e d to m i n i m i z e t h e amount o f d e t e c t e d s u r f a c e - I t was shown t h a t o p t i c s e r r o r s i n c o u n t e r - t y p e p r o c e s s o r s .

s c a t t e r e d l a s e r l i g h t ( f l a r e ) . A l l these c o n s i d e r a - these e r r o r s a r e p a r t i c u l a r l y s i g n i f i c a n t f o r probe number o f f r i n g e s and f o r t i o n s must be i n c l u d e d i n t h e d e s i g n o f an LA t o volumes c o n t a i n i n g a s m a l l o b t a i n t h e maximum amount o f a c c u r a t e d a t a i n minimum h i g h l y t u r b u l e n t f l o w .

e x p e r i m e n t a l r u n t i m e s . Experiments i n t u r b o m a c h i n e r y t e s t f a c i l i t i e s usu- HOST experiments where r e s e a r c h e r s planned t o use a l l y have h i g h o p e r a t i o n a l c o s t s , so i t i s necessary t o d e t e r m i n e c r i t i c a l t e c h n o l o g y a r e a s . Exten- LA were s t u d i e d t o a c q u i r e t h e d e s i r e d d a t a i n a minimum t i m e .

Research programs were t h e n conducted i n s e v e r a l o f s i v e o p e r a t o r i n t e r a c t i o n w i t h t h e i n s t r u m e n t a t i o n d u r - these areas i n c l u d i n g o p t i c a l d e s i g n , seed g e n e r a t i o n , i n g a t e s t r u n i s u s u a l l y n o t d e s i r a b l e . To p r o v i d e s i g n a l p r o c e s s i n g , and d a t a a c q u i s i t i o n . An ambient f o r e f f i c i e n t d a t a a c q u i s i t i o n and c o r r e c t p r o c e s s o r s e t t i n g s , a c o m p u t e r - c o n t r o l l e d i n t e r f a c e ( c a l l e d a p r e s s u r e , l a b o r a t o r y - t y p e combustor was used t o e v a l u - a t e o p t i c a l systems and s i g n a l p r o c e s s o r s . p r e p r o c e s s o r ) was designed, f a b r i c a t e d , and t e s t e d ( O b e r l e . 1987). The p r e p r o c e s s o r ( F i g . 9 ) a m p l i f i e s from t h e p h o t o d e t e c t o r , f i l t e r s i t u s i n g M o d e l i n g o f Fringe-Type LA t h e s i g n a l e t a l . . b o t h low- and high-pass f i l t e r s , and t h e n r o u t e s i t t o The f r i n a e - t v o e LA was a n a l v z e d ( S e a s h o l t z 1984) u s i n g f h e &amer-Rao lowe; bound for t h e v a r i - t h e c o u n t e r p r o c e s s o r .

ance o f t h e e s t i m a t e o f t h e Doppler f r e q u e n c y as a The c h i e f v i r t u e o f t h e p r e p r o c e s s o r i s t h a t i t f i g u r e o f m e r i t . Mie s c a t t e r i n g t h e o r y was used t o p r o v i d e s d i r e c t computer c o n t r o l o f t h e PMT h i g h v o l t - c a l c u l a t e t h e D o p p l e r s i g n a l w i t h b o t h t h e a m p l i t u d e age, t h e r f g a i n (50 dB o f a m p l i f i c a t i o n and a program- t o p r o v i d e c o n t r o l o v e r t h e and phase o f t h e s c a t t e r e d l i g h t t a k e n i n t o account. mable a t t e n u a t o r a r e used range -77 dB t o +50 dB i n 1 dB s t e p s ) , and s e l e c t i o n The n o i s e due to w a l l s c a t t e r ( f l a r e ) was c a l c u l a t e d

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u a l images o f t h e component d u r i n g o p e r a t i o n . T h i s i s o f t h e low- and high-pass f i l t e r s ( 8 low-pass and 8 h i g h - p a s s ) . I n a d d i t i o n , t h e p r e p r o c e s s o r p r o v i d e s n o t l i k e l y t o produce q u a n t i t a t i v e d a t a b u t , i n some cases, q u a l i t a t i v e d a t a a r e s u f f i c i e n t o r even p r e f e r a - computer c o n t r o l of t h e seed g e n e r a t o r and a l l o w s com- b l e . A case i n p o i n t i s t h e Combustor Viewing System p u t e r m o n i t o r i n g of t h e PMT dc c u r r e n t . With p r o p e r (Morey, 1984; Morey, 1985). T h i s system was designed s o f t w a r e , t h e p r e p r o c e s s o r w i l l a l l o w t h e r e s e a r c h e r t o p r o v i d e r e c o r d e d images o f t h e i n t e r i o r o f a combus- t o preprogram t h e v a r i o u s p r o c e s s o r s e t t i n g s based on tor d u r i n g o p e r a t i o n ; t h e o b j e c t i v e was t o produce a t h e expected f l o w c o n d i t i o n s . I t w i l l a l s o be p o s s i - v i s u a l r e c o r d of some o f t h e causes o f premature h o t b l e to use " s m a r t " a d a p t i v e s o f t w a r e t o s e l e c t t h e s e c t i o n f a i l u r e .

p r o p e r s e t t i n g s based c u r r e n t measurement parameters The Combustor V i e w i n g System c o n s i s t s o f a water such as t h e f r e q u e n c y , t u r b u l e n c e i n t e n s i t y , and n o i s e c o o l e d o p t i c a l p r o b e , a probe a c t u a t o r , an o p t i c a l i n - l e v e l .

t e r f a c e u n i t t h a t couples t h e probe t o cameras and t o an i l l u m i n a t i o n source, and system c o n t r o l s . The probe Four-Spot LA w i t h i t s a c t u a t o r i s d e s i g n e d t o mount d i r e c t l y on an The c o n v e n t i o n a l f r i n g e - t y p e LA has a l a r g e accept- engine o r a combustor. The probe i s 12.7 mm i n diam- i t can measure v e l o c i t i e s h a v i n g a ance a n g l e ( i . e . , e t e r , small enough t o f i t i n t o an i g n i t e r p o r t . The wide range o f flow a n g l e s ) . b u t i t has a r e l a t i v e l y a c t u a t o r p r o v i d e s a r o t a t i o n a l m o t i o n o f e180" and l a r g e probe volume. T h i s l a r g e probe volume l i m i t s r a d i a l i n s e r t i o n t o a maximum d e p t h o f 7 . 6 cm. Two t h e c l o s e s t measurements t o about 1 mm from s u r f a c e s .

probes were b u i l t t o use w i t h t h e system. The wide The c o n v e n t i o n a l t i m e - o f - f l i g h t LA (aka two-spot o r f i e l d - o f - v i e w probe can be f i t t e d w i t h lenses f o r 90" t r a n s i t LA) has a much s m a l l e r probe volume, which and 60" f i e l d s - o f - v i e w , w i t h t h e v i e w i n g a x i s o r i e n t e d a l l o w s i t to measure much c l o s e r t o s u r f a c e s . How- 45" t o t h e a x i s of t h e p r o b e . The narrow f i e l d - o f - v i e w t h e two-spot LA has a v e r y l i m i t e d acceptance e v e r , probe has lenses f o r 35" and 13" f i e l d s - o f - v i e w t h a t a n g l e , which g r e a t l y reduces i t s c a p a b i l i t i e s i n h i g h l y a r e o r i e n t e d 60' r e l a t i v e t o t h e probe a x i s . Both t u r b u l e n t f l o w s .

probes a r e water c o o l e d and gas purged and a r e capable The need for an anemometer i n c o r p o r a t i n g t h e l a r g e o f o p e r a t i n g w i t h i n t h e p r i m a r y combustion zone o f a acceptance a n g l e of t h e f r i n g e LA and t h e a b i l i t y o f combustor.

t h e two-spot LA t o measure c l o s e t o w a l l s l e d t o t h e F i g u r e s 12(a) and ( b ) show c r o s s s e c t i o n views o f development o f a new t y p e o f t i m e - o f - f l i g h t LA ( L a d i n g , t h e two probes. I n each case an image c o n d u i t i s used 1983; Wernet and Edwards, 1986). The new Four-Spot LA, to t r a n s f e r t h e image t h r o u g h t h e l e n g t h o f t h e probe.

shown i n F i g . 10, i n c o r p o r a t e s two f e a t u r e s . One i s mm i n The image c o n d u i t i s a f u s e d b u n d l e o f f i b e r s 3 t h e use of e l l i p t i c a l r a t h e r t h a n c i r c u l a r spots t o d i a m e t e r and c o n s i s t s o f about 75 000 f i b e r s 10 p m i n g i v e a l a r g e acceptance a n g l e . ( T h i s use o f two e l l i p - Each of these f i b e r s corresponds to a p i c - d i a m e t e r .

t i c a l s p o t s i s a l s o c a l l e d a two-dash o r two-sheet t u r e element. The image c o n d u i t i s 33 cm l o n g and i s t i m e - o f - f l i g h t LA.) The o t h e r f e a t u r e , which i s coupled to a f l e x i b l e f i b e r b u n d l e which connects t h e i s t h e use o f f o u r beams arranged t o f o r m two unique, probe t o t h e o p t i c a l i n t e r f a c e u n i t . Each probe i s p a i r s o f o r t h o g o n a l l y p o l a r i z e d , p a r t i a l l y o v e r l a p p i n g a l s o equipped w i t h two 1 mm d i a m e t e r p l a s t i c c l a d f u s e d s p o t s . T h i s a l l o w s t h e use of an o p t i c a l method t o q u a r t z f i b e r s used f o r i l l u m i n a t i o n when r e q u i r e d .

a c c u r a t e l y d e t e r m i n e t h e s t a r t and s t o p t i m i n g s i g n a l s .

The o p t i c a l i n t e r f a c e u n i t c o n t a i n s cameras, fil- P r e v i o u s l y , d e l a y - a n d - s u b t r a c t t e c h n i q u e s were used t o t e r s , and an i l l u m i n a t i o n source. E i t h e r f i l m or g e n e r a t e t h e t i m i n g s i g n a l s . T h e o p t i c a l method, v i d e o cameras can be r e m o t e l y s e l e c t e d and up t o e i g h t u n l i k e d e l a y and s u b t r a c t , i s independent o f t h e v e l o c - f i l t e r s can be i n s e r t e d i n t o t h e v i e w i n g p a t h . The i t y . T h i s i s advantageous i n h i g h l y t u r b u l e n t f l o w o r i l l u m i n a t i o n source i s a mercury a r c lamp which i s i n o t h e r flows w i t h a wide range o f v e l o c i t i e s .

focused on t h e ends of t h e i l l u m i n a t i o n f i b e r s .

The Four-Spot LA was designed, f a b r i c a t e d , and suc- T h i s system has been used i n b o t h combustor and c e s s f u l l y t e s t e d . Measurements were o b t a i n e d as c l o s e f u l l s c a l e engine t e s t s . A l t h o u g h t h e o r i g i n a l use for as 75 pm from a normal s u r f a c e (Wernet, 1987). Compar- t h e system was i n combustor l i n e r d u r a b i l l t y s t u d i e s , i s o n measurements were a l s o made u s i n g t h e f o u r - s p o t t h e system a l s o has c a p a b i l i t y as a f l o w p a t h diagnos- LA, a two-spot LA, and a f r i n g e - t y p e LA i n t h e v i c i n - t i c d e v i c e . It has been used t o examine l i g h t o f f and i n t h e exhaust o f i t y o f a s i n g l e t u r b i n e vane mounted b l o w o u t c h a r a c t e r i s t i c s and appears t o have c o n s i d e r a - t h e open j e t b u r n e r (Wernet and O b e r l e , 1987).

b l e p o t e n t i a l f o r o t h e r t i m e dependent phenomena and for f l a m e r a d i o m e t r y . Subsequent t o t h e i n i t i a l d e v e l - Windows and C o r r e c t i o n O p t i c s opment program, a d d i t i o n a l systems were b u i l t and p u t I n t u r b o m a c h i n e r y s t u d i e s i t i s h i g h l y d e s i r a b l e t o i n t o s e r v i c e i n a i r c r a f t engine development work and o b t a i n measurements w i t h o u t a l t e r i n g t h e f l o w b e i n g i n t e s t i n g t u r b i n e engines used t o g e n e r a t e e l e c t r i c a l s t u d i e d . W i t h o p t i c a l t e c h n i q u e s t h i s means t h a t t h e power.

window c o n t o u r should match t h e i n t e r n a l flow passage c o n t o u r . One Lewis HOST f a c i l i t y was a 508 mm diam- H I G H TEMPERATURE S T R A I N MEASURING SYSTEMS e t e r , s i n g l e stage, a x i a l flow t u r b i n e f a c i l i t y . Two c y l i n d r i c a l windows were designed t o a l l o w measurements The most a m b i t i o u s i n s t r u m e n t a t i o n development w i t h i n t h e s t a t o r and r o t o r passages. These windows, e f f o r t i n t h i s program i s t h e development o f high-tem- however, a c t as c y l i n d r i c a l lenses t h a t i n t r o d u c e aber- p e r a t u r e s t r a i n measuring systems. The t a r g e t goal f o r r a t i o n s i n t o t h e LA o p t i c a l system. I f n o t c o r r e c t e d , t h i s work i s to measure s t r a i n (approx 2000 m i c r o - these a b e r r a t i o n s can g r e a t l y degrade t h e measurements s t r a i n , maximum) a t temperatures up t o 1250 K w i t h an o r even p r e v e n t any measurements. A monochromatic cor-

u n c e r t a i n t y of + l o p e r c e n t . T h i s r e q u i r e m e n t i s f o r

r e c t i o n o p t i c ( F i g . 1 1 ) was designed for t h i s a p p l i c a - r e l a t i v e l y s h o r t t e r m t e s t i n g ; a 50 h r sensor l i f e i s t i o n (Wernet and S e a s h o l t z , 1987). The a d d i t i o n o f t h e c o n s i d e r e d s u f f i c i e n t . S p a t i a l r e s o l u t i o n o f t h e o r d e r c o r r e c t i o n o p t i c r e s t o r e s t h e d i f f r a c t i o n l i m i t e d p e r - o f 3 mm i s d e s i r e d and where measurements a r e r e q u i r e d formance o f t h e o p t i c a l system.

on b l a d e s or vanes, l a r g e temperature g r a d i e n t s a r e a n t i c i p a t e d . I n g e n e r a l , t h e r e q u i r e m e n t i s f o r COMBUSTOR V I E W I N G S Y S T E M s t e a d y - s t a t e measurements as d i f f e r e n t i a t e d from dynamic ( f l u c t u a t i n g component o n l y ) measurements.

Another way t o d e t e r m i n e t h e response o f a compo- n e n t t o t h e h o t s e c t i o n environment i s t o m o n i t o r v i s -

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T h e principal c a n d i d a t e f o r m a k i n g such measure- mal c y c l e s showed an a v e r a g e ( o v e r the t e m p e r a t u r e ments u n d e r s i m i l a r but lower t e m p e r a t u r e c o n d i t i o n s range) standard d e v i a t i o n of 1 3 0 ppm. The g r e a t e s t (less than a p p r o x 7 0 0 K) is the r e s i s t a n c e s t r a i n gage. 700 K w th a standard v a r i a t i o n w a s a t a p p r o x i m a t e l y However, a t t h e h i g h e r t e m p e r a t u r e s , s t r a i n measure- d e v i a t i o n o f 2 4 5 ppm. The long t e r m d ift of cast sam- ments b e c o m e i n c r e a s i n g l y d i f f i c u l t a n d the c o m m o n l y ples of this a l l o y a t 1100 and 1 2 5 0 K n a i r and in used s t r a i n g a g e s a r e marginal a t best. A s t h e re- a r g o n is shown in Fig. 15. It should be noted that quired t e m p e r a t u r e r a n g e i n c r e a s e s , t h e m a g n i t u d e of these d a t a imply a r e p e a t a b i l i t y in r e s i s t a n c e measure- the c o r r e c t i o n f o r a p p a r e n t s t r a i n b e c o m e s ment t o the o r d e r of 100 ppm; it is likely that some of s u b s t a n t i a l l y larger than t h e s t r a i n signal a n d the the f l u c t u a t i o n i n t h e s e c u r v e s is a t t r i b u t a b l e t o the u n c e r t a i n t y of the c o r r e c t i o n is excessive. To meet m e a s u r i n g s y s t e m r a t h e r than the r e s i s t a n c e of the of the t h e g o a l s listed a b o v e , the u n c e r t a i n t y alloy s a m p l e s .

a p p a r e n t s t r a i n c o r r e c t i o n must be less t h a n t2CO The r e p e a t a b i l i t y of the P d C r a l l o y is the pro- m i c r o s t r a i n . This r e q u i r e m e n t t r a n s l a t e s t o a repeat- perty t h a t we feel is essential f o r high-temperature of t h e r e s i s t a n c e v e r s u s t e m p e r a t u r e f o r t h e a b i l i t y s t r a i n g a g e work. However, t h e r e a r e o t h e r properties m o u n t e d s t r a i n g a g e t o be well w i t h i n 2400 p a r t s per r e q u i r e d f o r good s t r a i n g a g e s and the P d C r a l l o y may m i l l i o n (ppm), based o n a g a g e f a c t o r of two.

not be ideal c o n s i d e r i n g t h e s e p r o p e r t i e s . The temper- We m a d e a n e x t e n s i v e study of p o t e n t i a l l y useful a t u r e c o e f f i c i e n t o f r e s i s t a n c e is high e n o u g h that h i g h - t e m p e r a t u r e static strain m e a s u r e m e n t t e c h n i q u e s t e m p e r a t u r e c o m p e n s a t i o n will be r e q u i r e d ; t h e added ( H u l s e et al., 1987a). A s a r e s u l t of t h i s study, w e c o m p l i c a t i o n and the larger g a g e size required f o r this a r e p u r s u i n g t h e f o l l o w i n g t o i m p r o v e o u r high tempera- will have t o be a c c o m m o d a t e d . O t h e r potential problems ture s t r a i n m e a s u r i n g capability: such a s o x i d a t i o n r e s i s t a n c e o f high surface-to-volume ( 1 ) d e v e l o p i n g improved high t e m p e r a t u r e s t r a i n r a t i o t h i n f i l m s and f i n e wires, g a g e f a c t o r c h a n g e s with t e m p e r a t u r e , a n d the e l a s t i c / p l a s t i c s t r a i n prop- g a g e s ( 2 ) l e a r n i n g h o w better t o u s e a v a i l a b l e s t r a i n e r t i e s are still u n d e r investigation.

g a g e s (3) d e v e l o p i n g optical s t r a i n m e a s u r i n g s y s t e m s a s W o r k W i t h A v a i l a b l e S t r a i n G a q e s a l t e r n a t i v e s t o s t r a i n g a g e s L e a r n i n g how best t o u s e a v a i l a b l e s t r a i n g a g e s in T h e f o l l o w i n g s e c t i o n will d i s c u s s t h e s e t h r e e a r e a s o f high-temperature a p p l i c a t i o n s r e q u i r e s t h a t consider-' work. a b l e experimental w o r k be d o n e t o e x p l o r e s t r a i n gage c h a r a c t e r i s t i c s and d e v i s e o p t i m u m p r o c e d u r e s f o r spec- D e v e l o p m e n t of Improved High T e m p e r a t u r e S t r a i n C a g e s ific a p p l i c a t i o n s . S u c h w o r k i s v e r y t i m e c o n s u m i n g , I n a t t e m p t i n g t o d e v e l o p improved high t e m p e r a t u r e e s p e c i a l l y w h e n t e s t s at m a n y d i f f e r e n t t e m p e r a t u r e s s t r a i n g a g e s , we a r e e m p h a s i z i n g d e v e l o p m e n t of a l l o y s in a r e required. C o n s e q u e n t l y , o n e of o u r o b j e c t i v e s w i t h v e r y r e p e a t a b l e r e s i s t a n c e v e r s u s t e m p e r a t u r e this w o r k w a s t o e s t a b l i s h a c o m p u t e r c o n t r o l l e d test- c h a r a c t e r i s t i c s (Hulse e t al., 1 9 8 5 ; H u l s e et al., ing c a p a b i l i t y a t NASA Lewis so that t e s t i n g c o u l d be 1987b). W e tested a number of a l l o y c o m p o s i t i o n s f r o m a c c o m p l i s h e d with minimal o p e r a t o r a t t e n t i o n .

five a l l o y f a m i l i e s . T h e s e a l l o y f a m i l i e s a r e F e C r A l , The automated s t r a i n gage test l a b o r a t o r y h a s the NiCrSi (Nicrosil), P t P d M o , P d C r , and PtW. In all c a s e s c a p a b i l i t y t o m e a s u r e a p p a r e n t s t r a i n a n d g a g e f a c t o r e x c e p t f o r t h e t h e r m o c o u p l e a l l o y Nicrosil, w e looked o v e r a r a n g e o f t e m p e r a t u r e s f r o m 3 0 0 t o 1 3 7 0 K. T h e a t a r a n g e of c o m p o s i t i o n s . A l l o y s a m p l e were cast i n t o laboratory has t w o o v e n s (one of w h i c h c o n t a i n s a t e s t r o d s a n d t h e n m a c h i n e d i n t o s u i t a b l e t e s t samples.

f i x t u r e for a c o n s t a n t s t r a i n beam), a c o m p u t e r con- M e a s u r e m e n t s were m a d e o f r e s i s t a n c e v e r s u s t e m p e r a t u r e trolled a c t u a t o r for d e f l e c t i n g t h e b e a m , s t r a i n g a g e o v e r a n u m b e r of c y c l e s in w h i c h c o o l i n g r a t e s were and t e m p e r a t u r e i n s t r u m e n t a t i o n , a n d a personal com- varied f r o m 5 0 t o 2 5 0 K l m i n u t e . Additional t e s t s puter f o r c o n t r o l l i n g t h e t e s t s a n d c o l l e c t i n g the included o x i d a t i o n ( w e i g h t g a i n m e t h o d ) and r e s i s t a n c e data. C o m m u n i c a t i o n between v a r i o u s parts of t h e sys- d r i f t f o r u p t o 3 hr in a i r at 1 2 5 0 K. The r e s u l t s of tem is a c c o m p l i s h e d using both an IEEE-488 d a t a bus a n d t h e s e t e s t s indicated t h a t t w o a l l o y s , o n e in the an RS-232 serial interface. A v e r y v e r s a t i l e control FeCrAl f a m i l y and o n e in t h e P d C r f a m i l y , had t h e best program was d e v e l o p e d t h a t a l l o w s us t o c o n s t r u c t a potential f o r high t e m p e r a t u r e s t r a i n gage v a r i e t y o f test profiles by e n t e r i n g a s e r i e s of tem- a p p l i c a t i o n s .

p e r a t u r e s and c o m m a n d s t a t e m e n t s i n t o a d a t a set.

T h e FeCrAl a l l o y w a s d e s i g n a t e d a s "Mod 3." The Figure 16 shows a b l o c k d i a g r a m of the system.

f r a c t i o n a l r e s i s t a n c e c h a n g e with t e m p e r a t u r e f o r this O n e a p p r o a c h t o b e t t e r u t i l i z a t i o n o f a v a i l a b l e a l l o y a t t e m p e r a t u r e s u p t o 1 2 5 0 K is compared with t h e s t r a i n g a g e s is o u t l i n e d by S t e t s o n (1984). I n t h i s commercial Kanthal A-1 ( a l s o FeCrAl) a l l o y in Fig. 13.

w o r k u s i n g Kanthal A-1 alloy. it w a s determined that I n t h i s c a s e both a l l o y s w e r e a n n e a l e d f o r 2 hr at t h e a p p a r e n t s t r a i n of the g a g e w a s s t r o n g l y affected 1 1 5 0 K prior t o t e s t i n g . The r e s i s t a n c e c h a n g e o f t h e by t h e r a t e a t which the gage w a s c o o l e d f r o m t h e high- Mod 3 a l l o y is m u c h l e s s t h a n t h a t of t h e Kanthal A-1 est u s e temperature. F u r t h e r , t h e a p p a r e n t s t r a i n f o r a l l o y a n d s h o w s c o m p a r a t i v e l y l i t t l e c h a n g e f o r differ- the n e x t thermal c y c l e f o l l o w e d t h a t e s t a b l i s h e d by t h e ent c o o l i n g rates. T h i s a l l o y d o e s , however, e x h i b i t c o o l i n g part of the previous c y c l e ; a r e p e a t a b l e appar- different r e s i s t a n c e v e r s u s t e m p e r a t u r e characteris- ent s t r a i n could be o b t a i n e d if t h e c o o l i n g r a t e could t i c s , d e p e n d i n g o n p r e v i o u s thermal history. Figure 14 be r e p r o d u c e d d u r i n g e a c h thermal cycle. This implies i l l u s t r a t e s t h i s e f f e c t f o r e x p o s u r e t o 1 2 5 0 K air f o r that a n a c c u r a t e a p p a r e n t s t r a i n c o r r e c t i o n could be t i m e s r a n g i n g f r o m 10 t o 1 0 5 hr. Because of t h i s o b t a i n e d by m a t c h i n g t h e c o o l i n g r a t e d u r i n g calibra- e f f e c t , w o r k o n t h i s a l l o y has been de-emphasized in t i o n t o that which would be impressed o n the s t r a i n f a v o r of t h e P d C r a l l o y .

gage d u r i n g use. It is n e c e s s a r y , o f c o u r s e , that t h e The P d C r alloy has a r e s i s t a n c e v e r s u s t e m p e r a t u r e c o o l i n g r a t e s be c o n t r o l l a b l e d u r i n g u s e and that is curve w h i c h is c h a r a c t e r i s t i c of a solid s o l u t i o n not a l w a y s possible. But f o r t h e w o r k of S t e t s o n a l l o y with n o phase o r internal s t r u c t u r e c h a n g e s (1984). the c o o l i n g r a t e s could be matched a n d , being e v i d e n t . T h e r e s i s t a n c e is e s s e n t i a l l y linear a l t h o u g h it t o o k c o n s i d e r a b l e e f f o r t , the result was w i t h t e m p e r a t u r e a n d not a f f e c t e d by c h a n g e s in cool- u s a b l e s t a t i c s t r a i n m e a s u r e m e n t s at t e m p e r a t u r e s up ing r a t e o r p r e v i o u s thermal history. Cycle-to-cycle t o 9 5 0 K.

r e p e a t a b i l i t y of t h e f r a c t i o n a l c h a n g e in r e s i s t a n c e W o r k based o n control 1 ed cool i ng r a t e s has a1 so w i t h t e m p e r a t u r e is e x c e l l e n t . T e s t s o v e r four t h e r been undertaken at NASA Lewis. H a s t e l l o y X p l a t e s 13

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by 20 c m w e r e i n s t r u m e n t e d w i t h Kanthal A - 1 and a t t e m p t we r e c o r d e d specklegrams of a combustor l i n e r Chinese FeCRAl 700 " C (Wu e t a l . , 1981) s t r a i n gages.

i n a h i g h - t e m p e r a t u r e , h i g h - p r e s s u r e combustor t e s t r i g A p l a t e h o l d i n g f i x t u r e was made t h a t p e r m i t t e d c o o l - ( S t e t s o n , 1984). The specklegrams were t a k e n t h r o u g h i n g gas t o f l o w o v e r t h e p l a t e u n i f o r m l y so as t o g e t a v i e w i n g p o r t i n t h e p r e s s u r e v e s s e l o f t h e t e s t r i g c o n t r o l l e d c o o l i n g r a t e s . The Kanthal A - I gages were as combustor p r e s s u r e and temperature were v a r i e d . A mounted u s i n g a flame sprayed alumina and ceramic p o t e n t i a l p r o b l e m i n t h i s a p p l i c a t i o n i s t h a t t h e h i g h - cement process and t h e Chinese gages w e r e mounted w i t h p r e s s u r e c o o l i n g a i r f l o w i n g o v e r t h e e x t e r i o r s u r f a c e a Chinese ceramic cement u s i n g d i r e c t i o n s s u p p l i e d w i t h o f t h e combustor l i n e r i s i n t h e o p t i c a l v i e w i n g p a t h , t h e gages. The p l a t e s were a l s o i n s t r u m e n t e d w i t h 10 and t u r b u l e n c e i n t h e gas f l o w may cause s u f f i c i e n t thermocouples so as t o measure t h e t e m p e r a t u r e d i s t r i - o p t i c a l d i s t o r t i o n t o p r e v e n t c o r r e l a t i o n o f succeed- b u t i o n a t t h e s t r a i n gages. Apparent s t r a i n measure- i n g p a i r s o f specklegrams. Examples o f u n d i s t o r t e d ments were made o v e r a temperature range f r o m 300 t o and d i s t o r t e d specklegrams a r e shown i n F i g s . 1 8 t a ) 950 K w i t h c o o l i n g r a t e s c o n t r o l l e d a t 0.1, 1.0, and and ( b ) . T h i s e f f e c t proved to be a fundamental l i m i - 5.6 K / s e c . F i g u r e 1 7 shows t h e r e s u l t i n g r e s i s t a n c e t a t i o n f o r t h e measuring system i n t h i s a p p l i c a t i o n versus t e m p e r a t u r e d a t a . P l o t t e d h e r e a r e f r a c t i o n a l when combustor p r e s s u r e was h i g h e r t h a n a p p r o x i m a t e l y changes i n r e s i s t a n c e for one each o f t h e K a n t h a l A - I 3 atm. W e i n t e n d t o e x p l o r e f u r t h e r h i g h t e m p e r a t u r e and Chinese gages f o r t h e t h r e e d i f f e r e n t c o o l i n g a p p l i c a t i o n s o f o p t i c a l s t r a i n measuring systems.

r a t e s . The d a t a show t h e Kanthal gage t o be s t r o n g l y dependent on c o o l i n g r a t e b u t r e p e a t a b l e i n r e s i s t a n c e T H I N FILM SENSORS a t t h e maximum temperature. The r e s i s t a n c e of t h e Chinese gage i s independent o f c o o l i n g r a t e a t b o t h One o f t h e fundamental p r e c e p t s of e x p e r i m e n t a t i o n 300 and 950 K, b u t a t i n t e r m e d i a t e t e m p e r a t u r e s t h e i s t h a t t h e sensors used t o g e t e x p e r i m e n t a l d a t a must curves d e v i a t e depending on c o o l i n g r a t e . The maximum n o t p e r t u r b t h e s u b j e c t o f t h e experiment from i t s con- d e v i a t i o n s i n these curves o c c u r i n t h e t e m p e r a t u r e d i t i o n p r i o r t o t h e i n t r o d u c t i o n o f t h e sensors. I n range from 650 t o 800 K, r o u g h l y t h e same r e g i o n f o r t u r b i n e engine t e s t i n g t h e r e a r e many s i t u a t i o n s i n which h i g h d r i f t r a t e s have been r e p o r t e d f o r t h e which t h i s p r e c e p t may be v i o l a t e d . A p r i m e example i s Chinese gages ( H o b a r t , 1985).

t h e measurement o f t u r b i n e a i r f o i l surface temperature.

C o n v e n t i o n a l t e c h n o l o g y i n v o l v e s l a y i n g sheathed t h e r - O p t i c a l S t r a i n Measurement mocouple w i r e i n t o grooves c u t i n t o t h e s u r f a c e o f t h e O o t i c a l svstems mav n o t o r o v i d e e x a c t a l t e r n a t i v e s a i r f o i l , t h e n c o v e r i n g t h e i n s t a l l a t i o n and smoothing t o r e s i s t a n c e - s t r a i n gages f o r a1 1 t u r b i n e e n g i n e t h e a i r f o i l c o n t o u r . Although t h e a i r f o i l c o n t o u r i s a p p l i c a t i o n s , b u t t h e y appear t o have h i g h p o t e n t i a l r e s t o r e d , t h e thermocouple d i s t u r b s t h e t e m p e r a t u r e f o r p r o v i d i n g h i g h t e m p e r a t u r e , n o n c o n t a c t , two- d i s t r i b u t i o n , does n o t g i v e a t r u e measure of t h e o u t - d i m e n s i o n a l s t r a i n measuring systems w i t h v i r t u a l l y s i d e s u r f a c e t e m p e r a t u r e , and t h r e a t e n s t h e i n t e g r i t y u n l i m i t e d s t r a i n range. An o p t i c a l t e c h n i q u e t h a t o f t h e s t r u c t u r e o f t h i n w a l l e d b l a d e s and vanes.

r e q u i r e s n o m o d i f i c a t i o n t o t h e s u r f a c e under t e s t The t h i n f i l m thermocouple shown i n F i g . 19 uses l a s e r s p e c k l e p a t t e r n s . These p a t t e r n s a r e formed appears t o be an i d e a l s o l u t i o n for b l a d e and vane sur- by c o n s t r u c t i v e and d e s t r u c t i v e i n t e r f e r e n c e o f l a s e r face t e m p e r a t u r e measurement ( G r a n t and Przybyszewski, l i g h t r e f l e c t e d f r o m a d i f f u s e s u r f a c e . The source o f 1980; G r a n t e t a l . , 1981; Grant e t a l . , 1982). A s seen t h e p a t t e r n i s t h e i r r e g u l a r i t i e s i n t h e s u r f a c e ; when i n t h e c r o s s - s e c t i o n a l s k e t c h o f t h e sensor i n F i g . 20, t h e s u r f a c e i s d i s t o r t e d , for example by s t r a i n i n t h e t h e sensor has minimal i n t r u s i v e n e s s . I n t h i s case t h e p l a n e o f t h e s u r f a c e , t h e s p e c k l e p a t t e r n changes.

b l a d e o r vane, c o a t e d w i t h an M C r A l Y a n t i c o r r o s i o n P r e c i s e measurements o f changes i n r e c o r d e d s p e c k l e c o a t i n g , i s p o l i s h e d and t h e n o x i d i z e d t o form an p a t t e r n s can p r o v i d e i n f o r m a t i o n on t h e s t r a i n imposed adherent s u r f a c e c o a t i n g o f aluminum o x i d e . Addi- on t h e s u r f a c e . A p r a c t i c a l i m p l e m e n t a t i o n o f t h i s i s d e p o s i t e d o v e r t h i s f i l m t o t i o n a l aluminum o x i d e t e c h n i q u e i s a l a s e r s p e c k l e photogrammetric system i n form an e l e c t r i c a l l y i n s u l a t i n g f i l m o f r o u g h l y 2 p m which s p e c k l e p a t t e r n s a r e r e c o r d e d on p h o t o g r a p h i c t h i c k n e s s . F i l m s o f thermocouple a l l o y ( P t and f i l m ( S t e t s o n , 1983). Speckle p a t t e r n photographs PtlOXRh) a r e s p u t t e r d e p o s i t e d t h r o u g h a p p r o p r i a t e ( c a l l e d specklegrams) a r e made a t d i f f e r e n t increments masks so t h a t t h e f i l m s o v e r l a p a t one p o i n t t o form o f l o a d i n g o f t h e t e s t sample and t h e n p a i r s o f speck- t h e thermocouple j u n c t i o n . The thermocouple f i l m s legrams a r e examined i n an automated i n t e r f e r o m e t r i c e x t e n d t o t h e r o o t o f t h e vane where c o n n e c t i o n s t o The system uses heterodyne tech- photocomparator. c o n v e n t i o n a l l e a d w i r e s a r e made. F i l m - t o - l e a d w i r e con- n i q u e s t o a c h i e v e a c c u r a t e measurements t o a f r a c t i o n n e c t i o n s a r e made by p a r a l l e l - g a p w e l d i n g . The com- of an i n t e r f e r e n c e f r i n g e . No a t t e m p t w i l l be made p l e t e i n s t a l l a t i o n o f i n s u l a t i n g f i l m and thermocouple o f l e s s t h a n 20 pm. The h e r e t o d e s c r i b e t h i s system i n d e t a i l ; i t has been a l l o y f i l m s has a t h i c k n e s s t h o r o u g h l y d e s c r i b e d i n t h e open 1 i t e r a t u r e ( S t e t s o n , i n s t a l l a t i o n has n o t changed t h e c o n t o u r or t h e s t r e n g t h of t h e component and t h e g r e a t e s t t h e r m a l 1983) .

The l a s e r s p e c k l e photogrammetric system has changes apparent a r e t h e d i f f e r e n t absorptance and s u c c e s s f u l l y measured h i g h - t e m p e r a t u r e s u r f a c e deforma- f i l m s compared t o t h e e m i t t a n c e o f t h e thermocouple t i o n . S t e t s o n (1983) d e s c r i b e s an e x p e r i m e n t t o meas- o x i d i z e d M C r A l Y s u r f a c e . The t e c h n o l o g y f o r t h i n f i l m o f an u n r e s t r a i n e d p l a t e o f u r e t h e thermal expansion thermocouples and t u r b i n e a i r f o i 1 s has been developed H a s t e l l o y X a t temperatures up t o 1150 K . The p l a t e t o t h e e x t e n t t h a t i n s t r u m e n t e d vanes and b l a d e s a r e was heated i n a l a b o r a t o r y f u r n a c e t o 1150 K and t h e n b e i n g used i n t u r b i n e engine t e s t s a t temperatures up a l l o w e d t o c o o l t o 500 K o v e r a p e r i o d o f s e v e r a l to 1250 K .

200 K h o u r s . Specklegrams were r e c o r d e d a t r o u g h l y T h i n f i l m sensor development work i s g o i n g on b o t h i n t e r v a l s d u r i n g t h e h e a t i n g and c o o l i n g and suc- a t c o n t r a c t o r f a c i l i t i e s and a t NASA Lewis. f i g u r e 21 c e e d i n g specklegram p a i r s were used t o d e t e r m i n e t h e shows t h e t h i n f i l m sensor l a b o r a t o r y a t NASA Lewis.

thermal expansion o f t h e p l a t e . Measured thermal The l a b o r a t o r y i s housed i n a c l e a n r o o m i n which b o t h expanison agreed w i t h values c a l c u l a t e d f r o m t h e meas- temperature and h u m i d i t y a r e c o n t r o l l e d . On t h e l e f t u r e d t e m p e r a t u r e and t h e thermal expansion c o e f f i c i e n t i n t h e photograph a r e t h r e e vacuum s p u t t e r i n g machines t o w i t h i n 3 p e r c e n t . for d e p o s i t i o n o f b o t h i n s u l a t o r and sensor f i l m s . I n W e have a t t e m p t e d t o use t h e l a s e r s p e c k l e photo- t h e r i g h t - h a n d c o r n e r o f t h e room i s equipment for I n one grammetric system i n t e s t c e l l environments. p h o t o l i t h o g r a p h y o f sensors; c o n v e n t i o n a l p h o t o - r e s i s t t e c h n i q u e s a r e used. A t t h e f a r r i g h t edge o f t h e pho- Grant, H . P . , Przybyszewski, J . S . , C l a i n g , R . G . . and t o g r a p h i s a welder f o r c o n n e c t i n g l e a d w i r e s t o sensor Anderson, W.L., 1982. " T h i n F i l m Temperature Sensors, f i l m s .

Phase 111," NASA CR-165476.

CONCLUDING REMARKS Hobart, H . F . , 1985, " E v a l u a t i o n R e s u l t s o f t h e 7OO0C Chinese S t r a i n Gages." NASA TM-86973.

T h i s paper has reviewed t h e s t a t e o f development of a number o f advanced i n s t r u m e n t a t i o n p r o j e c t s a p p l i c a - Holanda, R . , 1984, " A n a l y s i s o f T h e r m o e l e c t r i c b l e t o t h e h o t s e c t i o n s o f t u r b i n e e n g i n e s . Most o f P r o p e r t i e s o f High-Temperature Complex A l l o y s o f these p r o j e c t s a r e complete and t h e i n s t r u m e n t a t i o n i s Nickel-Base, Iron-Base, and Cobalt-Base Groups," NASA i n use. T h i s i s t h e case for t h e Combustor V i e w i n g TP-2278.

System, t h e Dynamic Gas Temperature Measuring System, t o t a l h e a t f l u x sensors, t h e l a s e r anemometry p r o j e c t s Hulse, C . O . , B a i l e y , R . S . , and Lemkey, F . D . , 1985, d e s c r i b e d h e r e , and t h i n f i l m thermocouples. Work i n "High Temperature S t a t i c S t r a i n Gage A l l o y Development t h e g e n e r a l a r e a o f t h i n f i l m sensors i s c o n t i n u i n g i n Program," NASA CR-174833.

o r d e r t o f u r t h e r improve t h e t e c h n o l o g y and expand sen- sor t y p e s and a p p l i c a t i o n s . The work t o improve o u r Hulse, C . O . , e t a l . , 1986, "Advanced High Temperature h i g h - t e m p e r a t u r e s t r a i n measuring c a p a b i l i t y i s s t i l l S t a t i c S t r a i n Sensor Development," NASA CR-179520.

i n p r o g r e s s .

Hulse, C.O., B a i l e y , R . S . , G r a n t , H . P . , and REFERENCES Przybyszewski, J.S., 1987, " H i g h Temperature S t a t i c S t r a i n Gage Development C o n t r a c t , " NASA CR-180811.

A t k i n s o n , W . H . , and S t r a n g e , R . R . , 1982, "Development o f Advanced High-Temperature Heat F l u x Sensors," NASA Lading, L . , 1983. " E s t i m a t i n g Time and Time-Lag ir!

CR-165618. T i m e - o f - F l i g h t V e l o c i m e t r y , " A p p l i e d O p t i c s , Vol. 22, NO. 22, pp. 3637-3643.

A t k i n s o n , W.H., H o b a r t , H.F., and Strange, R . R . , 1983, "Advanced H i g h Temperature Heat F l u x Sensors," Morey, W . W . . 1984, "Hot S e c t i o n V i e w i n g System." NASA Proceedings o f t h e 3 8 t h I n s t r u m e n t S o c i e t y o f America CR-174773.

Conference, Advances i n I n s t r u m e n t a t i o n . V o l . 38, P a r t 2, I n s t r u m e n t S o c i e t y o f America, pp. 1457-1479. Morey, W . W . , 1985, " J e t Engine Combustor V i e w i n g System," Conference on Lasers and E l e c t r o - O p t i c s , A t k i n s o n , W.H., C y r , M . A . , and S t r a n g e , R . R . , 1984, I E E E , New York, p. 298.

" T u r b i n e Blade and Vane Heat F l u x Sensor Development, Phase I." NASA CR-168297. O b e r l e , L.G., and S e a s h o l t z , R.G., 1985, " F i l t e r Induced E r r o r s i n Laser Anemometry U s i n g A t k i n s o n , W . H . , C y r , M . A . , and S t r a n g e , R . R . , 1985a, Counter-Processor,'' I n t e r n a t i o n a l Symposium on Laser "Development o f High-Temperature Heat F l u x Sensors, Anemometry, ASME FED V o l . 33, A . Dybbs and P . A . Pfund, Phase 11 - V e r i f i c a t i o n T e s t i n g , " NASA CR-174973. eds., ASME, New York, pp. 221-230.

A t k i n s o n . W . H . , C y r , M . A . , and Strange, R . R . , 1985b, O b e r l e , L.G., 1987, " A Computer C o n t r o l l e d S i g n a l " T u r b i n e Blade and Vane Heat F l u x Sensor Development, Preprocessor f o r Laser F r i n g e Anemometer Phase 11." NASA CR-174995. A p p l i c a t i o n s , " NASA TM-88982.

Elmore, D.L., Robinson, W . W . , and Watkins, W.B., 1983, S e a s h o l t z , R . G . , O b e r l e , L.G., and Weikle, D.H.. 1984, "Dynamic Gas Temperature Measurement System F i n a l " O p t i m i z a t i o n o f Fringe-Type Laser Anemometers f o r R e p o r t , Volume I T e c h n i c a l E f f o r t s , " NASA CR-168267.

T u r b i n e Engine Component T e s t i n g , " A I A A Paper 84-1459.

(NASA TM-83658).

Elmore, D.L., Robinson, W . W . , and Watklns, W . B . , 1984, "Dynamic Gas Temperature Measurement System," S t e t s o n , K . A . , 1983, "The Use o f Heterodyne Speckle Proceedings o f t h e 3 0 t h I n t e r n a t i o n a l I n s t r u m e n t a t i o n Photogrammetry t o Measure High-Temperature S t r a i n Symposium, I n s t r u m e n t a t i o n i n t h e Aerospace I n d u s t r y , D i s t r i b u t i o n s , " H o l o g r a p h i c Data N o n d e s t r u t i v e Vol. 30, Advances i n T e s t Measurements, Vol. 21, T e s t i n g , D . V u k i c e v i c . ed., Proc. SPIE-370, S P I E , I n s t r u m e n t S o c i e t y o f America, pp. 289-302.

B e l l i n g h a m , WA. pp. 46-55.

Elmore, D.L., Robinson, W . W . , and Watkins, W.B., S t e t s o n , K . A . , 1984, "Demonstration T e s t o f Burner 1986a, " F u r t h e r Development o f t h e Dynamic Gas L i n e r S t r a i n Measuring System," NASA CR-174743.

Temperature Measurement System, Vol . I T e c h n i c a l

E f f o r t s , I' NASA CR- 17951 3.

Stocks, D.R.. and Elmore, D.L., 1986, " F u r t h e r Development o f t h e Dynamic Gas Temperature Measurement Elmore, D.L.. Robinson, W . W . , and Watkins, W.B., - Computer Program U s e r ' s Manual," System, V o l . I 1 1986b. " F u r t h e r Development o f t h e Dynamic Gas NASA CR-179513-VOL-2.

A I A A Paper 86-1648.

Temperature Measurement System," Wernet, M . P . . and Edwards, R . V . , 1986, " I m p l e m e n t a t i o n G r a n t , H . P . , and Przybyszewski. J . S . , 1980, " T h i n F i l m of a New Type o f T i m e - o f - F l i g h t Laser Anemometer," Temperature Sensor," NASA CR-159782.

A p p l i e d O p t i c s , Vol. 25, No. 5 . pp. 644-648.

G r a n t , H . P . , Przybyszewski, J . S . , and C l a i n g , R . G . , Wernet, M . P . , 1987a, "Four Spot Laser Anemometer and 1981, " T u r b i n e Blade Temperature Measurements U s i n g O p t i c a l Access Techniques for T u r b i n e Engine T h i n F i l m Temperature Sensors," NASA CR-165201. A p p l i c a t i o n s , " ICIASF ' 8 7 , I n t e r n a t i o n a l Congress on I n s t r u m e n t a t i o n i n Aerospace S i m u l a t i o n f a c i l i t i e s , I E E E , New York, pp. 245-254. (NASA TM-88972).

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W e r n e t , M . P . , a n d O b e r l e , L . G . , 1 9 8 7 b . " L a s e r Wu, T . T . , Ma, L . C . , and Zhao, L . B . , 1 9 8 1 , " D e v e l o p m e n t Anemometry T e c h n i q u e s f o r T u r b i n e A p p l i c a t i o n s , " ASME o f T e m p e r a t u r e Compensated R e s i s t a n c e S t r a i n Gages for P a p e r 87-GT-241. (NASA TM-88953). Use t o 7OO0C," E x p e r i m e n t a l M e c h a n i c s . Vol. 2 1 . No. 7 ~ . - - -, p p . 117-123.

W e r n e t , M.P., and S e a s h o l t z , R . G . , 1 9 8 7 c , "Zoom L e n s C o m p e n s a t o r for a C y l i n d r i c a l Window i n L a s e r Anemometer U s e s , " A p p l i e d O p t i c s , Vol. 26, No. 2 1 .

p p . 4603-4611.

ALUtEL 7 r CHROMEL r C E R M I C INSULATING

\ PlATERIAL ( F I L L )

I *0.8 CM D I A . - * *NOT TO SCALE NOT TO SCALE ALUMEL , ALUREL ,

/--cHRorm *

/ / / / / HOT S I D E - HOT SIDE ALUMEL 1-2 = SENSOR OUTPUT 1-2 = TREFERENCE 1-3 = SENSOR OUTPUl 1-3 = TREFERENCE FIGURE 1. - EMBEDDED THERMOCOUPLE HEAT FLUX SENSOR. FIGURE 2.

- GARDON GAGE HEAT FLUX SENSOR.

FIGURE 3. - HEAT FLUX SENSORS INSTALLED I N T U R B I E VANE.

U c W I COMBUSTOR PRESSURE, ATP( - COMPARISON OF HEAT FLUX CONDUCTED THROUGH THE FIGURE 5.

F I G U R E 4. - COMBUSTOR SEGMENT INSTRU- COMBUSTOR L I N E R AND I N C I D E N T RADIANT HEAT FLUX FOR V A R I - MENTED WITH HEAT FLUX SENSORS.

OUS LEVELS OF COMBUSTOR PRESSURE. RADIANT HEAT FLUX WAS MEASURED WITH A COMMERCIAL RADIOMETER.

- DUAL ELEMENT THERMOCOUPLE PROBE FOR MEASURING FLUCTUATING FIGURE 6.

GAS TEMPERATURE.

0 0 %

c E 2 -40 0 1 0 0 2 o o m 4 o o m -2 0 1 0 0 2 o o m 4 0 0 5 0 0

(A) 250 pn THERMOCOUPLE UNCWENSATED.

( B ) 75 pn THERMOCOUPLE UNCWENSATED.

loo0

P looO

& 500 500 0 0

~w~~ , T ' I l,y11~; 1 ' I r , . r s 1 -500tis I ; , 1 ; ' , ' ; , , I : I 1

-500 ~ 2 1 8 K RMS -loo0 -1oOoo 100 200 300 400 500 225 235 245 255 265 275 T I E E , WSEC (C) 75 pn THERMOCOUPLE CWENSATED.

(D) 75 pM THERMOCOUPLE CWENSATED.

FIGURE 7 . - DYNAMIC G A S TEM'ERATURE SIGNALS F R W AN ENGINE TEST.

n w PHOTOMULTIPLIER INPUT SELECTED T I E -5 -10

B

o i HIGH PASS

' -15

1 2 3 4 5 10 (A) F/4 OPTICS.

CW A R ATOR AWL I F IER

Q

Lrl

LOW PASS

n ALARM

FILTER BANK I PROGRAMABLE BUFFER1 OUTPUT COUNTER TO DATA ACQUISI- WALL DISTANCE. rW TION (B) ~ / 2 . 5 OPTICS.

FIGURE 8. - SIGNAL-TO-NOISE RATIO

FIGURE 9. - LASER FRINGE A N E M T E R PRE-PROCESSOR SIGNAL FLOW DIAGRAM (SNR) FOR OPTIMUM MASK VERSUS SHOWING THE DOPPLER SIGNAL I N THE TIME DOMAIN AT THREE POINTS I N DISTANCE O F PROBE V O L U E FROM THE SIGNAL FLOW.

WALL.

LINEARLY L l Ql W l L?

I I .

L POLARIZED c HORIZONTAL POLARIZATION

INPUT I t

t ' I VERTICAL POLARIZATION

\

L3 B P h l D POLARIZATION

L7 w3 "2 L 4 L5 L6

E M SPLITTER FIGURE 10. - SCHEMTIC VIEW O F THE TRANSNITTING AND RECEIVING OPTICS, FIGURE 11. - SCHEMTIC VIEW OF A LASER ANENOETER SYSTEH APPLIED TO A TURBINE R I G INCORPORATING A CURVE CASING WINDOW.

THE ABERRATIMS INDUCED BY THE TURBINE WINDOW ARE C W E N S A T E D FOR BY THE CORRECTION OPTIC.

AS THE 3-AXIS TABLE SCANS THE PROBE V O L U E THROUGH THE M A C 4 PASSAGE, THE CORRECTION OPTIC POSITION I S ADJUSTED BY ANOTHER ACTUATOR. I N T H I S POSITION. THE PROBE V O L W I S JUST I N S I D E THE T U R B I R WINDOW, AND THE ACTUATOR I S AT I T S FURTHEST POSITION FRM THE F/5 LENS.

VIEWING LENS-\, '\ -i ILLUNINATING FIBER W A COOL I NG , L 1 2 . 7 nn D I A .

FIGURE 1 2 ( A ) . - CROSS SECTION OF WIDE F I E L D OF VIEW COMBUSTOR 40 VIEWING PROBE.

f n LL \ CL

I M A G E 7 I L L U N I NATl NG

-a

FIBERS 7 , ,,FIBER

-40 -80 000 2 7 3 4 7 3 6 7 3 8 7 3 1 0 7 3 1 2 7 3 1 4 7 3 TEMPERATURE, K FIGURE 1 3 . - FRACTIONAL RESISTANCE CHANGE OF KANTHAL A-1 AND FECRAL COOL I NG NOD # 3 AS A FUNCTION OF TEMPERATURE.

' 1 L 1 2 . 7 m D I A .

FIGURE 12(B). - CROSS SECTION OF NARROW F I E L D OF VIEW COMBUSTOR VIEWING PROBE.

60 O O O r

- 1100 K. ARGON

1 000 1250 K. A I R r n f 20 CL n

a

-a -500 CL

a

-a 10 1250 K. ARGON

1 - 1

10 20 30 40 50 TIME, HR FIGURE 15. - LONG-TERM RESISTANCE DRIFT OF PDCR ALLOY I N ARGON AND A I R .

10-CHANEL RS 232 D I G I T A L THERMOCOUPLES T H E R M X T E R D I G I T A L TO OVEN 2 PROGRAmR IEEE 488 STRAIN GAGE NULT I E T E R PERIPHERALS ACTUATOR I 10-CHANNEL

-

STRAIN GAGE READOUT FIGURE 16. - BLOCK DIAGRAM O F THE HIGH E W E R A T U R E STRAIN SYSTF*.

GAGE TESTING 5.6 K/SEC A-1 GAGE 1.0 K/SEC 0.1 K/SEC L 15 OOO \ $j 10

-r

OOO - I -5

o o s t 3 L 4 L A A 7 L 8 L A 1 L

TEW'ERATURE. K FIGURE 17. - FRACTIONAL RESISTANCE CHANGE VERSUS TEMPERATURE FOR KANTHAL A-1 AND 700 O C CHINESE GAGES WITH THREE DIFFERENT COOL- ING RATES.

FIGURE 1 8 ( A ) . - SPECKLEGRAM OF COMBUSTOR LINER WITH NO DISTORTION DUE TO FLOW.

- SPECKLEGRAM OF COMBUSTOR LINER WITH DISTORTION FROM FIGURE 1 8 ( B ) .

I TURBULENT GAS FLOW.

PRES.

FIGURE 19.

- A TURBINE VANE INSTRUMENTED WITH T H I N F I L M THERMOCOUPLES.

r SPUllERED FILM /' THERMOCOUPLE - OXIDE LAYER": - M C r A l Y COATING (SPUllERED OR EVAPORATED) ORIGINAL METAL SURFACE BASE METAL "THE STABLE ADHERENT A I 2 4 INSULATING LAYER IS OBTAINED LEAST 5Ghr OXIDATION (AT 1300 K ) OF THE COATING.

BY AT FOLLOWED B Y A 1 2 9 SPUTTERING.

FIGURE 20. - T H I N FILM THERMOCOUPLE CROSS SECTION.

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F I G U R E 21. - T H I N FlLN SENSOR LABORATORY AT T H E L E W I S RESEARCH C E N T E R ,

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ASSESSMENT, DEVELOPMENT, AND APPLICATION OF COMBUSTOR AEROTHERMAL MODELS J. D. Holdeman National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio H. C. Mongia Allison Gas Turbine Division General Motors Corporation Indianapolis, Indiana E. J. Mularz Propulsion Directorate US. Army Aviation and Technology Activity - AVSCOM NASA Lewis Research Center Cleveland, Ohio ABSTRACT E m p i r i c a l l y based p r o c e d u r e s have l e d t o success- f u l e v o l u t i o n a r y combustor improvements. However, as The gas t u r b i n e combustion system d e s i g n and t h e s e methods a r e experience-based, t h e y a r e n o t we1 1 development e f f o r t i s an e n g i n e e r i n g e x e r c i s e t o o b t a i n s u i t e d when combustor d e s i g n r e q u i r e m e n t a r e s i g n i f - an a c c e p t a b l e s o l u t i o n t o t h e c o n f l i c t i n g d e s i g n t r a d e - i c a n t l y d i f f e r e n t from t h a t o f c u r r e n t t e c h n o l o g y o f f s between: combustion e f f i c i e n c y , gaseous emis- e n g i n e s . The r a p i d l y d e v e l o p i n g CFD ( C o m p u t a t i o n a l s i o n s , smoke, i g n i t i o n , r e s t a r t , l e a n b l o w o u t , b u r n e r F l u i d Dynamics) c a p a b i l i t y i s p r o v i d i n g an a d d i t i o n a l e x i t t e m p e r a t u r e q u a l i t y , s t r u c t u r a l d u r a b i l i t y , and tool i n t h e d e s i g n p r o c e s s w n i c h can have a p o w e r f u l l i f e c y c l e c o s t . For many y e a r s , t h e s e combustor p o s i t i v e i n f l u e n c e o n f u t u r e d e s i g n c a p a b i l i t y . I n d e s i g n t r a d e - o f f s have been c a r r i e d o u t w i t h t h e h e l p t h e s e codes, combustion system subcomponents i n c l u d i n g o f fundamental r e a s o n i n g and e x t e n s i v e component and d i f f u s e r s , f u e l i n j e c t o r s , and combustor l i n e r s , i n bench t e s t i n g , backed b y e m p i r i c a l and e x p e r i e n c e t o t h e complex i n t e r n a l flow, need t o be accu- a d d i t i o n c o r r e l a t i o n s . r a t e l y m o d e l l e d . To a c h i e v e t h i s , p h y s i c a l sub-models Recent advances i n t h e c a p a b i l i t y o f c o m p u t a t i o n a l t o and a c c u r a t e n u m e r i c a l schemes must be d e v e l o p e d f l u i d dynamics (CFD) codes have l e d t o t h e i r a p p l i c a - d e s c r i b e t h e v a r i o u s aerothermochemical p r o c e s s e s t i o n t o complex t h r e e - d i m e n s i o n a l f l o w s such as t h o s e o c c u r r i n g w i t h i n t h e combustion chamber.

i n t h e gas t u r b i n e combustor. A number o f U . S . Govern- A number o f U . S . Government and company sponsored ment and i n d u s t r y sponsored programs have made s i g n i f i - t o t h e programs have made s i g n i f i c a n t c o n t r i b u t i o n s c a n t c o n t r i b u t i o n s t o t h e f o r m u l a t i o n , development, f o r m u l a t i o n , development, and v e r i f i c a t i o n o f an and v e r i f i c a t i o n o f an a n a l y t i c a l combustor d e s i g n a n a l y t i c a l combustor d e s i g n methodology. These have methodology which w i l l b e t t e r d e f i n e t h e a e r o t h e r m a l i n c l u d e d : U . S . Army Combustor D e s i g n C r i t e r i a V a l i d a - l o a d s i n a combustor, and be a v a l u a b l e tool for d e s i g n t i o n (Bruce e t a l . , 1979; Mongia e t a l . , 1979, Mongia o f f u t u r e combustion systems. The c o n t r i b u t i o n s made and Reynolds, 1979). NASA S w i r l i n g R e c i r c u l a t i n g Flow b y NASA Hot S e c t i o n Technology (HOST) sponsored Aero- ( S r i n i v a s a n and Mongia, 1980). NASA Soot and NOx Emis- t h e r m a l M o d e l i n g and s u p p o r t i n g programs a r e d e s c r i b e d s i o n s P r e d i c t i o n ( S r i v a t s a , 1980), NASA P r i m a r y Zone S t u d y ( S u l l i v a n e t a l . , 1983), NASA Mass and Momentum i n t h i s p a p e r .

T r a n s f e r (Johnson and B e n n e t t , 1981; Roback and INTRODUCTION Johnson, 1983; Johnson e t a l . , 1984). NASA L a t e r a l J e t I n j e c t i o n ( L i l l e y , 1986; F e r r e l l and L i l l e y , 1985; The g o a l o f gas t u r b i n e combustion system d e s i g n McMurray and L i l l e y , 1986; Ong and L i l l e y , 1986), NASA and development i s t o o b t a i n an a c c e p t a b l e s o l u t i o n t o D i l u t i o n J e t M i x i n g ( S r i n i v a s a n e t a l . , 1982, 1984, t h e c o n f l i c t i n g d e s i g n t r a d e - o f f s between combustion 1985; S r i n i v a s a n and White, 1986; Holdeman e t a l . , e f f i c i e n c y , gaseous e m i s s i o n s , smoke, i g n i t i o n , 1984; Holdeman and S r i n i v a s a n , 1986; Holdeman e t a ] . , r e s t a r t , l e a n b l o w o u t , b u r n e r e x i t t e m p e r a t u r e q u a l i t y , 1987a). NASA T r a n s i t i o n M i x i n g S t u d y (Reynolds and s t r u c t u r a l d u r a b i l i t y , and l i f e c y c l e c o s t . F o r many W h i t e , 1986; Holdeman e t a l . , 1987b). NASA HOST Aero- t h e r m a l M o d e l i n g (Kenworthy e t a l . , 1983; S t u r g e s s , y e a r s , t h e s e combustor d e s i g n t r a d e - o f f s have been c a r - r i e d out w i t h t h e h e l p o f fundamental r e a s o n i n g and 1983; S r i n i v a s a n e t a l . , 1983a, 1983b). NASA Error e x t e n s i v e component and bench t e s t i n g , backed b y e m p i r - R e d u c t i o n (Syed e t a l . . 1985). i n d u s t r y I R & D p r o - i c a l and e x p e r i e n c e c o r r e l a t i o n s . The u l t i m a t e g o a l grams, and advanced combustor development programs.

has been t o d e v e l o p a r e l i a b l e combustor d e s i g n system The NASA H o t S e c t i o n Technology (HOST) Combustion t h a t can p r o v i d e q u a n t i t a t i v e l y a c c u r a t e p r e d i c t i o n s Program has s u p p o r t e d s e v e r a l o f t h e s e programs. The o f t h e complex combustion flow f i e l d c h a r a c t e r i s t i c s o v e r a l l o b j e c t i v e o f t h e HOST Combustion P r o j e c t i S t o ( F i g . 1 ) so t h a t an optimum combustion system d e s i g n d e v e l o p and v e r i f y advanced a n a l y t i c a l methods to can be a c h i e v e d w i t h i n r e a s o n a b l e c o s t and schedule improve t h e c a p a b i l i t y t o d e s i g n combustion systems c o n s t r a i n t s .

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(4) give quantitatively unsatisfactory for advanced aircraft gas turbine engines. T h i s objec- correlation with data for complex swirling tive is being approached both computationally and flows with recirculation zones experimentally.

( 5 ) give quantitatively unsatisfactory Computationally, HOST first sponsored studies to correlation, but predict trends correctly, for assess and evaluate the capabilities of tktsting complex three-dimensional flows.

aerothermal models (circa 1982). Based o n the results of these assessments and other studies in the liter- Algebraic Stress Model and Its Modifications ature, HOST supported several studies to develop new Mean flow predictions with this model agreed with and improved numerical methods for the analysis of tur- the data as well as the k--E model results, therefore bulent viscous recirculating flows, with emphasis on the conclusions above also apply to this model.

In accuracy and speed o f solution.

addition, the Algebraic Stress Model gives reasonable The objectives of HOST sponsored experimental predictions for the Reynolds stress components, con- of the flow phys- studies were to improve understanding of the k-& sistent with the strengths and limitations ics and chemistry in constituent flows, and to obtain models (Mongia et al., 1986).

fully-specified, benchmark-quality experimental data The results of standard k--E and algebraic and dif- suitable for the assessment of the capabilities of ferential Reynolds stress turbulence models, have been advanced computational codes.

compared in several continuing assessment studies. An This paper reviews the advances in the example comparison (Mongia, 1987) of data and calcula- state-of-the-art in combustor aerothermal modeling, tions using a hybridlSIMPLE numerical scheme is shown supported by the HOST while highlighting the programs in Fig. 3. This flow is that of co-annular turbulent Project (Turbine Engine Hot Section Technology, 1982, jets flowing into an axisymmetric sudden expansion 1983, 1984, 1985, 1986, 1987). Due t o length limita- (Roback and Johnson, 1983). In this figure, velocity tions not all programs that received HOST support are profiles are shown a t downstream, distance from 0.11 included, and, for completeness, some programs that to 2.5 pipe diameters from the expansion.

made a significant contribution, but which did not draw their primary support from HOST are discussed.

Scalar Transport Model Mongia et al.. (1986) reported that the k--E model AEROTHERMAL MODELING ASSESSMENT with specified Prandtl number oredicts scalar fluxeq reasonably well for flow where' the gradient diffusion Gas turbine combustion models include submodels approximation is valid.

An alternative, the algebraic of turbulence, chemical kinetics, turbulencelchemistry scalar transport model, has the CaDabilitv to i m m o v e interaction, spray dynamics, evaporation/combustion, predictions over the k-e approach,'but fu;ther work I - - is radiation, and soot formation and oxidation. A very needed to establish its validity for swirling recircu- extensive assessment of numerics, physical submodels, lating flows.

and the suitability of the available data was made by three contractors under Phase 1 of the HOST Aerothermal Turbulence/Chemistry Interaction Models Modeling program (Kenworthy et al., 1983; Sturgess, It was a l s o concluded bv Monaia e t al.. (1986) 1983; Srinivasan e t al., 1983a, 1983b). These investi- that both 2- and 4-step reaciion ;themes showed prom- gations surveyed and assessed current models and iden- ise f o r application in gas turbine combustors, but tified model deficiencies through comparison between need t o be further validated against data from simple Results of the calculated and measured quantities.

flames. The modified eddy breakup model predlcted assessment by Srinivasan et al., (1983a, 1983b) are trends well, and it was recommended that it should be summarized by Mongia et al. (1986). The constituent pursued because this approach could be easily extended flows examined included: (1) simple flows with n o t o multistep kinetic schemes.

streamline curvature, ( 2 ) complex flows without swirl, and (3) complex flows with swirl. Geometries for Numerical Accuracy several test cases from each of these categories are A significant deficiency identified in the assess- shown in Fig. 2. ments was that for many flows of interest the accuracy ~ ~ .

of the calculation was limited by the numerical approx- k--E Turbulence Model imations, wherein the false diffusion is of the same The k--E model is the simplest turbulence model order of magnitude as the turbulent diffusion. This that is suitable f o r recirculating flow calculations.

masked the differences between turbulence models such This model achieves closure by using a gradient trans- that very different models gave essentially the same port model for Reynolds stress with an isotropic eddy result. and sometimes resulted in undeservedly good viscosity. For flows where the isotropic eddy vis- agreement between data and predictions.

cosity assumption is not valid, the k--E model may be I f false diffusion is present, the numerical solu- either modified (e.g. low Reynolds number correction, tion obtained for any given flow depends o n the grid Richardson number correction) o r replaced with an alge- density and distribution. An example of the compari- braic o r differential Reynolds stress model.

sons made in the assessment program is given by the Assessment of the k--E model(s) of turbulence comparison in Figs. 4 and 5 between measured and calcu- showed that these models: lated temperature distributions downstream from a row f o r ( 1 ) require low Reynolds Number correction of jets entering a confined crossflow.

ne This f l o w is a predicting wall shear flows, and stream1 constituent flow in most gas turbine combustors, and curvature modifications for accurately has been treated extensively in the literature, includ- predicting curved boundary layers ing the recently completed NASA Dllution Jet Mixing th give quantitatively good correlation H (2) program, from which data were compared with three- data for simple flows and non-recirculat ng dimensional calculations in the Phase I assessment swirling flows study by Srinivasan et al., (1983).

for (3) give quantitatively reasonable results nonswirling recirculating flows

ORIGINAL PAGE W '

6 F POOR QUALtTY

o f i n t e r e s t . That i s , f l o w perfoPmance parameters The c a l c u l a t e d and e x p e r i m e n t a l r e s u l t s shown a r e f i e l d and g e o m e t r i c parameters t h a t a r e needed i n t h e for a s i n g l e row o f j e t s w i t h an o r i f i c e s p a c i n g t o e m p i r i c a l e q u a t i o n s , such as combustion volume and t h e d i a m e t e r r a t i o , S I D , = 2 i n j e c t e d i n t o a d u c t e d main- f r a c t i o n of a i r p a r t i c i p a t i n g i n t h e p r i m a r y combustion stream w i t h a d u c t h e i g h t t o o r i f i c e d i a m e t e r r a t i o r e a c t i o n , a r e p r o v i d e d by t h e a n a l y t i c a l c a l c u l a t i o n s .

H/D, = 8. The j e t - t o - m a i n s t r e a m momentum f l u x r a t i o , S a t i s f a c t o r y agreement w i t h e x p e r i m e n t a l d a t a has J , for t h i s t e s t was 25.32. C a l c u l a t i o n s f o r t h i s been shown ( R i z k and Mongia, 1986) for emissions, p e r - case made w i t h 4 5 x 2 6 ~ 1 7 (19890) nodes, a r e shown i n formance and h e a t t r a n s f e r . The combustor f o r which F i g . 4. The parameter p l o t t e d i n these f i g u r e s i s t h e d a t a w e r e a v a i l a b l e , and f o r which c a l c u l a t i o n s were d i m e n s i o n l e s s mean t e m p e r a t u r e d i f f e r e n c e r a t i o , T H E T A , performed, i s shown s c h e m a t i c a l l y i n F i g . 6 . A t y p i -

where THETA = (Tm - T ) / ( T m - T j ) . The p r e d i c t e d j e t

c a l comparison between d a t a and p r e d i c t i o n s f o r CO, p e n e t r a t i o n and m i x i n g a r e l e s s t h a n t h a t shown by t h e unburned hydrocarbons, NOx, s o o t e m i s s i o n s , combustion data.

e f f i c i e n c y , p a t t e r n f a c t o r , and l e a n b l o w o u t a r e shown The c a l c u l a t i o n shown i n F i g . 4 used 49 nodes to i n F i g s . 7 ( a ) t o ( g ) r e s p e c t i v e l y . The model i s i n s i m u l a t e each j e t . I t i s g e n e r a l l y n o t p o s s i b l e t o use good agreement w i t h t h e d a t a o v e r t h e e n t i r e s e a - l e v e l t h i s many g r i d p o i n t s i n such a small r e g i o n ; as f e w engine o p e r a t i n g range. C a l c u l a t e d l i n e r w a l l tempera- as f o u r may be used i n p r a c t i c e f o r each j e t . To simu- t h i s com- t u r e s f o r b o t h t h e i n n e r and o u t e r w a l l s o f l a t e t h e a c c u r a c y o f t h i s a p p r o x i m a t i o n , c a l c u l a t i o n s b u s t o r a r e shown i n F i g . 8 f o r t h r e e t y p i c a l z-planes were performed f o r t h e same f l o w and g e o m e t r i c c o n d i - k = 5, 14, and 23. Here k denotes nodal a l o n g t i o n s , b u t w i t h a 2 7 x 2 6 ~ 8(5615) g r i d . These coarse- p l a n e s a l o n g t h e combustor c i r c u m f e r e n t i a l d i r e c t i o n .

g r i d c a l c u l a t i o n s ( F i g . 5) a r e i n much b e t t e r agreement A l t h o u g h no d i r e c t comparison w i t h l i n e r w a l l tempera- w i t h t h e d a t a t h a n t h e f i n e - g r i d c a l c u l a t i o n s . These t u r e d a t a was made, t h e p r e d i c t i o n s look r e a s o n a b l e .

and o t h e r c a l c u l a t i o n s i n S r i n i v a s a n e t a l . , (1983b) c l e a r l y demonstrated t h a t t h e t h r e e - d i m e n s i o n a l c a l c u - AEROTHERMAL MODELING PHASE I 1 l a t i o n s were n o t g r i d independent.

Based on t h e recommendations o f t h e Phase I C o n c l u s i o n s from t h e Assessments assessment s t u d i e s , a c t i v i t i e s i n Phase I 1 of t h e HOST The major c o n c l u s i o n i n t h e HOST Aerothermal Aerothermal M o d e l i n g program c o n c e n t r a t e d on d e v e l o p i n g M o d e l i n g Phase I assessment s t u d i e s by Kenworthy improved n u m e r i c a l schemes, and c o l l e c t i n g c o m p l e t e l y - e t a l . (1983), S t u r g e s s (1983), and S r i n i v a s a n e t a l .

s p e c i f i e d d a t a f o r n o n r e a c t i n g s i n g l e and two-phase (1983a, 1983b) was t h a t t h e a v a i l a b l e c o m p u t a t i o n a l s w i r l i n g and n o n s w i r l i n g f l o w s . The programs i n i t i a t e d f l u i d dynamics (CFD) codes p r o v i d e d a u s e f u l combustor were: Improved Numerical Methods; Flow I n t e r a c t i o n d e s i g n tool. A l t h o u g h s i g n i f i c a n t advances have been S w i r l C h a r a c t e r i z a - Experiment; and Fuel I n j e c t o r j A i r made i n t h e development and v a l i d a t i o n o f m u l t i d i m e n - t i o n . The f i r s t of these i s a p r e r e q u i s i t e t o f u r t h e r s i o n a l gas t u r b i n e combustion c a l c u l a t i o n procedures, model development, and t h e d a t a o b t a i n e d i n t h e l a t t e r t h e codes assessed were o n l y q u a l i t a t i v e l y a c c u r a t e , two s t u d i e s w i l l be used t o v a l i d a t e advanced models e s p e c i a l l y f o r complex t h r e e - d i m e n s i o n a l f l o w s , and b e i n g developed i n d e p e n d e n t l y .

f u r t h e r work was needed. I t was concluded t h a t b o t h a s i g n i f i c a n t l y improved n u m e r i c a l scheme and f u l l y - Improved Numerical Methods s p e c i f i e d e x p e r i m e n t a l d a t a ( i . e . b o t h mean and t u r b u - The h y b r i d f i n i t e d i f f e r e n c i n g scheme employed i n l e n c e f l o w f i e l d q u a n t i t i e s , w i t h measured boundary g e n e r a l l y a v a i l a b l e combustor codes g i v e s e x c e s s i v e c o n d i t i o n s ) f o r complex n o n - r e a c t i n g and r e a c t i n g numerical d i f f u s i o n e r r o r s which p r e c l u d e a c c u r a t e c o n s t i t u e n t flows were needed b e f o r e v a r i o u s emerging q u a n t i t a t i v e c a l c u l a t i o n s . I n response t o t h i s d e f i - p h y s i c a l sub-models of t u r b u l e n c e , c h e m i s t r y , sprays, c i e n c y , HOST supported t h r e e programs w i t h t h e p r i m a r y t u r b u l e n c e l c h e m i s t r y i n t e r a c t i o n s , s o o t f o r m a t i o n / o b j e c t i v e t o i d e n t i f y , assess, and implement improved o x i d a t i o n , r a d i a t i o n , and h e a t t r a n s f e r c o u l d be prop- s o l u t i o n a l g o r i t h m s a p p l i c a b l e t o a n a l y s i s o f t u r b u - e r l y assessed.

l e n t v i s c o u s r e c i r c u l a t i n g f l o w s . Both s o l u t i o n accu- r a c y and s o l u t i o n e f f i c i e n c y were addressed ( T u r b i n e A SECOND GENERATION MODEL Engine Hot S e c t i o n Technology, 1985, 1986, 1987; Turan and VanDoormal, 1987).

The f i r s t g e n e r a t i o n combustor d e s i g n procedure For most p r a c t i c a l problems, a c e n t r a l d i f f e r - o u t l i n e d by Mongia and Smith (1978) has been v e r y use- e n c i n g scheme would be i d e a l l y s u i t e d i f i t were f u l f o r d e v e l o p i n g s e v e r a l combustors (Mongia e t a l . , u n c o n d i t i o n a l l y s t a b l e . C e n t r a l d i f f e r e n c i n g i s a 1986) t h a t e x h i b i t e d s i g n i f i c a n t t e c h n o l o g y advances.

s i m p l e second-order scheme which i s easy and s t r a i g h t - However, i n a d d i t i o n t o t h e model d e f i c i e n c i e s i d e n t i - f o r w a r d to implement. However, f o r g r i d P e c l e t num- f i e d i n t h e assessments, t h e r e were s e v e r a l parameters b e r s l a r g e r t h a n 2 , c e n t r a l d i f f e r e n c i n g can l e a d t o o f i m p o r t a n c e i n gas t u r b i n e combustor d e s i g n t h a t t h e o v e r - and under-shoots and i s u n s t a b l e . The h y b r i d a n a l y t i c a l models c o u l d n o t p r e d i c t ; e . g . gaseous emis- ( c e n t r a l / u p w i n d ) scheme i s s t a b l e f o r a l l P e c l e t num- s i o n s , s o o t f o r m a t i o n , f l a m e blow-out l i m i t s , combus- b e r s , b u t s u f f e r s from e x c e s s i v e f a l s e d i f f u s i o n . An t o r p a t t e r n f a c t o r , and l i n e r h e a t t r a n s f e r . These a l t e r n a t i v e scheme, named CONDIF ( C o n t r o l l e d Numerical parameters were, however, s u c c e s s f u l l y p r e d i c t e d by D i f f u s i o n w i t h I n t e r n a l Feedback) (Runchal e t a1 . , w e l l - e s t a b l i s h e d s e m i - a n a l y t i c a l c o r r e l a t i o n s developed 1986) has u n c o n d i t i o n a l l y p o s i t i v e c o e f f i c i e n t s and by P l e e and M e l l o r (1980). L e b f e v r e (1985). and t h e i r s t i l l m a i n t a i n s t h e e s s e n t i a l f e a t u r e s o f c e n t r a l d i f - a s s o c i a t e s . T h e r e f o r e , a combustor d e s i g n procedure f e r e n c i n g and i t s second-order accuracy.

t h a t c o u l d be a p p l i e d t o c u r r e n t and f u t u r e gas t u r b i n e CONDIF uses c e n t r a l d i f f e r e n c i n g when Pe < 2.

e n g i n e s was implemented t h a t makes use o f e m p i r i c a l Where Pe > 2 and t h e dependent v a r i a b l e v a r i e s monoton- d e s i g n concepts and employs a n a l y t i c a l m o d e l i n g t o o l s i c a l l y , a m o d i f i e d c e n t r a l d i f f e r e n c i n g scheme i s t o r e p r e s e n t v a r i o u s combustion processes ( R i z k and used, o t h e r w i s e upwind d i f f e r e n c i n g i s used. CONDIF Mongia, 1986; Mongia, 1987).

employs j u s t enough n u m e r i c a l d i f f u s i o n t o ensure s t a - T h i s method makes use o f m u l t i d i m e n s i o n a l models b i l i t y based i n t e r n a l l y on t h e f i e l d d i s t r i b u t i o n o f t o e s t a b l i s h l i n e r f l o w f i e l d f e a t u r e s and combustion c h a r a c t e r i s t i c s . The a n a l y t i c a l r e s u l t s a r e t h e n i n t e g r a t e d w i t h s e m i - e m p i r i c a l c o r r e l a t i o n s f o r

ORIGINAL PAGE IS

the variable, rather than switching t o upwind differ- 0r98?p0~ew&!&1 o f i n tere s t i s the i n terac t i o n 2 . Since upwinding is done encing whenever Pe exceeds between swirling flow and lateral jets in a rectan- at relatively few grid points, CONDIF essentially main- gular channel (Fig. 1 0 ) . The mainstreams flow enters tains the second-order accuracy of central differen- through 5 swirlers with the transverse jets injected cing. and false diffusion is substantially reduced. from both the top and bottom duct walls with either 2 Another advanced numerical scheme, called flux- or 4 jets per swirler at 1/2 or 1 channel height down- soline (Patankar et a l . , 1987). i s based o n a linear stream from the swirler.

variation of total flux (convection + diffusion These experiments are being conducted o n both air between two grid points. This is an improvement over and water multiple-swirler rigs, as well as single the assumption of uniform flux used in hybrid schemes, swirler and swirling j e t rigs. Fifteen cases (combina- and leads to reduced numerical diffusion. tions of swirl and jet strength and location) are under 30th of these schemes have been used to solve a test using laser sheet light and dye water flow visual- variety of analytical, two-dimensional laminar and tur- ization, and detailed velocity and scalar mean and tur- bulent flows (Runchal et al., 1987; Patankar et al., bulence LDV measurements are being made in the air rig.

1987). As an example, results for a laminar flow A key feature of this program is comparison of = 400) in a square driven cavity are shown in (Re model calculations against the data obtained to ensure Fig. 9. This f l o w , shown schematically in part a ) . is that the data are complete and consistent, and satisfy characterized by a strong recirculation zone typical the boundary condition input requirements of current of many physical situations. The problem was solved three-dimensional codes. Calculations were performed with both CONDIF and flux-spine schemes o n a uniform using a three-dimensional code (Srivasta, 1980) for all 22x22 grid and compared with the exact analytical solu- test cases before the experiments were begun. Data and tion and a hybrid solution o n an extremely fine 82x82 both previous and advanced model calculations are being grid. Velocity profiles at the midsection of the cav- compared as data are obtained.

ity are shown in Fig. 9(b). Both advanced schemes show improvement over the hybrid calculation. Fuel-InJectorIAir-Swirl Characterization of both CONDIF and flux- An attractive feature The objective of this studv is t o obtain fullv- spline schemes is that their extension to three dimen- specified mean and turbulence measurements of both-gas sions is relatively straight-forward. The resulting and droplet phases downstream of a fuel injector and linear differential equations involve only seven points air swirler typical of those used in gas turbine com- as opposed to 27 points needed in many skewed-upwind bustion chambers.

I schemes (Syed e t al., 1985). The flowfield of interest is an axisymmetric I n addition to the need for improved numerical particle-laden jet flow with and without confinement accuracy, there i s a need for improved computational and co-annular swirling air flow. Approximately 30 efficiency for a given level of accuracy. Typically cases are under test with both glass-bead particle- the continuity and momentum equations are solved sepa- laden jets and liquid sprays, with various combination of the rately, and then linked through iteration of swirl strengths and confinement (Turbine Engine Hot pressure term; e.g. SIMPLE (Semi-lmpllcit Method for Section Technology, 1985, 1986, 1987). Measurements - Pressure Linked Equations). Modifications, such as of mean and turbulence quantities, for both gas and SIMPLER and PISO, have been shown to improve computa- solid phazes are being made using a 2-component Phase/ Doppler LDV particle analyzer (McDonel1 et al., 1987).

I tional efficiency. Other advanced schemes (Turbine

Engine Hot Section Technology, 1985, 1986, 1987; Vanka. Calculations were performed for all test cases 1987). such as block correction techniques and direct with a two-dimensional TEACH-type nonreacting turbulent solution of the coupled equations have been proposed. viscous two-phase flow code before the experiments were Calculations with the latter coupled with the flux- begun. Data and both previous and advanced model spine technique have shown a speed increase by a fac- calculations are being compared as data are obtained

of 15 for a calculation of turbulent flow over a

tor (Mostafa et al., 1987, 1988; Nikjooy et al., 1988).

backward-facing step (Mongia, 1987).

In the first series of tests, the developing of unconfined single and two-phase flows, with regions Gas Phase Experiments 105 pm glass beads, have been examined experimentally An experimental study of the interactions between and analytically for particle-to-gas mass loadings of the combustor and diffuser systems (Srinivasan and 0.2 and 1.0. Data and calculations for the latter are 1 1 . A two-component Phase/Doppler sys- Thorp, 1987) is in progress to: shown in fig.

( 1 ) Identify the mechanisms and magnitude of tem was used t o map the flowfield, including particle of veloc- aerodynamic losses in various sections of an number density, and two orthogonal components annular combustor-diffuser system ity for both phases.

( 2 ) Determine the effects of geometric changes in Calculations are shown for both deterministic and the prediffuser, dome, and shroud o n these stochastic treatments of the particles, using a two- of the particles losses phase k-E model. Both treatments (3) Obtain a data base t o assess current and give the same gas-phase axial velocity profiles, how- advanced aerodynamic computer models for ever, the stochastic approach, which attempts t o model predicting these complex flowfields particle/gas phase interactions, gives better agree- ( 4 ) Upgrade the analytical models based o n the ment for particle quantities than the deterministic approach which ignores turbulence interactions.

experimental data I ( 5 ) Design and test advanced diffuser systems to Another experimental program was conducted t o I verify the accuracy of the upgraded analytical obtain information on the characteristics of the spray mode 1 produced by a gas turbine fuel injector (McVey et al., 1988a, 1988b). The objective of this study was to Another study in progress will obtain comprehen- sive mean and turbulence measurements of velocity and obtain spatially-resolved information o n both the species concentration in a three-dimensional flow mode1 liquid and gaseous phases of the spray flow field under of high-flow, high velocity, and high swirl of the primary zone of gas turbine combustion chambers conditions (Turbine Engine Hot Section Technology, 1985, 1986, that are typical of engine operation. Measurements Holdeman, J.D., Reynolds,- R . , and White, C . , 1987, were made w i t h a h i g h - r e s o l u t i o n s p r a y p a t t e r n a t o r , a " A Numerical Study o f t h e E f f e c t s o f C u r v a t u r e and two-component l a s e r v e l o c i m e t e r , and a single-component Convergence on D i l u t i o n J e t M i x i n g , " A I A A Paper Phase/Doppler p a r t i c l e a n a l y z e r .

87-1953.

The comprehensive e x p e r i m e n t a l d a t a generated i n these programs w i l l be used t o v a l i d a t e advanced models Johnson, B.V., and B e n n e t t , J.C., 1981. "Mass and o f t u r b u l e n c e , s c a l a r , and s p r a y t r a n s p o r t , i n c l u d i n g Momentum T u r b u l e n t T r a n s p o r t Experiments w i t h C o n f i n e d two-equation t u r b u l e n c e models, a l g e b r a i c and d i f f e r e n - C o a x i a l Jets:" NASA CR-165574.

t i a l Reynolds s t r e s s models, s c a l a r and s c a l a r - v e l o c i t y t r a n s p o r t models, and E u l e r i a n and Lagrangian d e t e r m i n - Johnson, B.V., Roback, R . , and B e n n e t t , J.C., 1984, i s t i c and s t o c h a s t i c spray models.

" S c a l a r and Momentum T u r b u l e n t T r a n s p o r t Experiments w i t h S w i r l i n g and N o n s w i r l i n g Flows," E x p e r i m e n t a l SUMMARY Measurements and Techniques i n T u r b u l e n t R e a c t i v e and Non-Reactive Flows, R.M.C. So, J.H. Whitlaw, and M.

A l t h o u g h s i g n i f i c a n t p r o g r e s s has been made i n Sapp, eds., ASME, New York, pp. 107-119.

I t h e development o f t h r e e - d i m e n s i o n a l a n a l y t i c a l CFD codes and t h e i r a p p l i c a t i o n i n f u t u r e gas t u r b i n e com- Kenworthy, M.J., Correa, S . M . , and B u r r u s , D.L., 1983, b u s t o r d e s i g n , t h e s e codes a r e n e i t h e r s u f f i c i e n t l y

"Aerothermal M o d e l i n g : Phase I F i n a l R e p o r t - Volume 1

comprehensive n o r q u a n t i t a t i v e l y a c c u r a t e enough t o Model Assessment," NASA CR-168296.

p e r m i t a complete d e s i g n a l o n e . They a r e , however, a v a l u a b l e component i n an e v o l v i n g combustor d e s i g n Lebfevre, A.H., 1985, " I n f l u e n c e o f Fuel P r o p e r t i e s o f methodology i n which t h e i r c a p a b i l i t y i s i n t e g r a t e d Gas T u r b i n e Combustor Performance," AFWAL-TR-84-1104, w i t h t h e s u b s t a n t i a l base of e m p i r i c a l e x p e r i e n c e and ( A v a i l . N T I S , AD-A151464).

flow modeling.

one-dimensional L i l l e y , D.G., 1986. " L a t e r a l J e t I n j e c t i o n i n t o T y p i c a l CONCLUDING REMARKS Combus tor Flowf i e l ds , I' NASA CR-3997.

The NASA HOST sponsored Aerothermal M o d e l i n g McDonell, V.G., Cameron, C.D., and Samuelsen, G . S . , Phase I 1 programs w i l l l e a d t o s i g n i f i c a n t improve- 1987, "Symmetry Assessment o f a Gas T u r b i n e A i r - B l a s t ments i n o u r t e c h n i c a l a b i l i t y t o p r e d i c t n o n r e a c t i n g Atomizer , " A I A A Paper 87-21 36.

gas t u r b i n e combustor flow f i e l d s w i t h and w i t h o u t spray i n j e c t i o n . S i g n i f i c a n t l y enhanced c a p a b i l i t i e s McMurry. C.B., and L i l l e y , D . B . , 1986, "Experiments on for a c c u r a t e l y p r e d i c t i n g combustor aerothermal p e r - Two Opposed L a t e r a l J e t s I n j e c t e d I n t o S w i r l i n g formance and w a l l t e m p e r a t u r e l e v e l s and g r a d i e n t s Crossflow," NASA CR-175041.

w i l l r e q u i r e f u r t h e r improvements i n n u m e r i c a l schemes and p h y s i c a l submodels. I t i s e q u a l l y i m p o r t a n t to McVey, J.B., Kennedy, J.B., R u s s e l l , S . , 1988, c o l l e c t f u l l y - s p e c i f i e d r e a c t i n g flow d a t a , s i m i l a r t o "Fuel-Injector/Air-Swirl C h a r a c t e r i z a t i o n F i n a l what i s b e i n g done f o r n o n r e a c t i n g f l o w s under HOST Report," U n i t e d Technologies Research L a b o r a t o r i e s , Phase 11, f o r b o t h complex c o n s t i t u e n t f l o w s , and U n i t e d Technologies Research C e n t e r , NASA CR-180864.

g e n e r i c gas t u r b i n e combustors.

I n p a r a l l e l , work s h o u l d c o n t i n u e i n t h e f o r m u l a - McVey, J.B.. Kennedy, J.B., R u s s e l l , S . , 1988, t i o n and s y s t e m a t i c v a l i d a t i o n o f t u r b u l e n t combustion " A p p l i c a t i o n o f Advanced D i a g n o s t i c s t o A i r b l a s t models f o r r e a c t i n g sprays and m u l t i d i m e n s i o n a l h e a t I n j e c t o r Flows." t o be p r e s e n t e d a t t h e 3 3 r d t r a n s f e r models. These c a p a b i l i t i e s w i l l p r o v i d e t h e I n t e r n a t i o n a l Aeroengine and Gas T u r b i n e Congress, t o o l s needed t o a n a l y t i c a l l y conduct t h e combustion Amsterdam, t h e N e t h e r l a n d s .

t r a d e - o f f s t u d i e s so t h a t optimum f u t u r e combustion systems can be designed, f a b r i c a t e d , and developed Mongia, H.C.. and Smith, K . G . , 1978, "An E m p i r i c a l / w i t h i n a c c e p t a b l e c o s t and schedule c o n s t r a i n t s .

for Gas T u r b i n e A n a l y t i c a l Design Methodology REFERENCES Combustors." A I A A Paper 78-998.

Bruce, T.W., Mongia, H.C., and Reynolds, R.S., 1979, Mongia, H . C . , Reynolds, R . S . , Coleman, E . , and Bruce,

I - Element

"Combustor Design C r i t e r i a V a l i d a t i o n , V o l .

T.W., 1979, "Combustor Design C r i t e r i a V a l i d a t i o n , Tests and Model V a l i d a t i o n , " USARTL-TR-78-551, ( A v a i l .

Volume I 1 - Development T e s t i n g o f Two F u l l - s c a l e

N I T S , AD-A067657).

Annular Gas T u r b i n e Combustors," USARTL-TR-78-556-VOL-2. ( A v a i l . N T I S , AD-A067689).

F e r r e l l , G.B., and L i l l e y , D.G., 1985, " D e f l e c t e d J e t Experiments i n a T u r b u l e n t Combustor F l o w f i e l d , " NASA Mongia, H . C . , and Reynolds, R . S . , 1979, "Combustor CR-174863.

Design C r i t e r i a V a l i d a t i o n . " Volume 111 - U s e r ' s

Manual." USARTL-TR-8-55C-VOL-3. ( A v a i l . N T I S , Holdeman, J.E., S r i n i v a s a n , R . , and B e r e n f e l d , A . , AD-A066793).

1984, "Experiments i n D i l u t i o n J e t M i x i n g , " A I A A J o u r n a l , Vol. 22, no. 10, pp. 1436-1443.

Mongia, H . C . , Reynolds, R . S . , and S r i n i v a s a n , R . , 1986, "Mu1 t i d i m e n s i o n a l Gas T u r b i n e Combustion Holdeman, J.D., and S r i n i v a s a n , R . , 1986, " M o d e l i n g M o d e l i n g : A p p l i c a t i o n s and L i m i t a t i o n s , " A I A A D i l u t i o n J e t F l o w f i e l d s , " J o u r n a l o f P r o p u l s i o n and J o u r n a l , Vol. 24, no. 6, pp. 890-904.

Power, Vol. 2, No. 1 , pp. 4-10.

Mongia, H., C . , 1987, " A S t a t u s Report on Gas T u r b i n e Holdeman, J.D., S r i n i v a s a n , R . , Coleman, E.B., Meyers, Combustor Modeling," p r e s e n t e d a t t h e AGARD Combustion G.D.. and White, C.D., 1987, " E f f e c t s o f M u l t i p l e Rows and F u e l s i n Gas T u r b i n e Engines Meeting, C r e t e , O c t .

and N o n c i r c u l a r O r i f i c e s on D i l u t i o n J e t M i x i n g , " 12-16.

J o u r n a l o f P r o p u l s i o n and Power, Vol. 3, No. 3, pp.

2 19-226.

Mostafa. A . A . , Mongia, H . C . , McDonell, V . G . , and S r i n i v a s a n , R . , and White, C . , 1986, " D i l u t i o n J e t Samuelsen, G . S . . 1987, "On t h e E v o l u t i o n o f P a r t i c l e - M i x i n g Program: Supplementary Report," NASA CR-175043.

Laden J e t Flows: A T h e o r e t i c a l and Experimental S t u d y , " A I A A Paper 57-2181. S r i n i v a s a n , R . , and Thorp, D . J . , 1987, "Combustor D i f f u s e r I n t e r a c t i o n Program," AFWAL-TR-86-2093, A i r Mostafa, A . A . . Mongia, H . C . , McDonell, V . G . , and Force W r i g h t A e r o n a u t i c a l Labs, W r i g h t P a t t e r s o n Samuelsen, G . S . , 1988, "On t h e E v o l u t i o n o f P a r t i c l e - A F B , OH.

Laden C o a x i a l J e t Flows: A T h e o r e t i c a l and Experimental Study," A I A A Paper 88-0239. S r i v a t s a , S . K . , 1982, "Computations o f Soot and NOx Emissions f r o m Gas T u r b i n e Combustors," NASA CR-165196.

N i k j o o y , M . . K a r k i , K . C . , Mongia, H . C . , McDonell, V . G . .

and Samuelsen, G . S . 1988, "K-E Turbulence Model S t u r g e s s , Geoffrey J . , 1983, "Aerothermal M o d e l i n g : Assessment w i t h Reduced Numerical D i f f u s i o n f o r Phase I F i n a l Report," NASA CR-168202.

C o a x i a l J e t s , " A I A A Paper 88-0342.

S u l l i v a n , R . E . , Young, E . R . . M i l e s , G . A . , W i l l i a m s , Ong. L . H . , and L i l l e y , D . G . , 1986, "Measurements o f a J . R . . 1983, "Small Gas Turbine Combustor P r i m a r y Zone S i n g l e L a t e r a l J e t I n j e c t e d i n t o S w i r l i n g C r o s s f l o w , " Study , " NASA CR-168122.

NASA CR-175040.

Syed, S . A . , C h i a p p e t t a , L.M., and Gosman, A.D., 1985, P a t a n k a r , S . W . , K a r k i , K . C . , and Mongia, H . C . , 1987, "Error R e d u c t i o n Program," NASA CR-174776.

"Development and E v a l u a t i o n o f Improved Numerical Schemes f o r R e c i r c u l a t i n g Flows, A I A A Paper 87-0061. Turan, A . , and VanDoormal, J . P . , 1987. "Improved Numerical Methods f o r T u r b u l e n t Viscous R e c i r c u l a t i o n Plee, S . L . , and M e l l o r , A . M . , 1979, " C h a r a c t e r i s t i c s F 1 ows , " NASA CR- 1 80852.

Time C o r r e l a t i o n for Lean B l o w o f f o f B l u f f - b o d y S t a b i l i z e d Flames," Combustion and Flame, Vol. 35, pp. T u r b i n e Enqine Hot S e c t i o n Technology (HOST) 1982 NASA 61-80. TM-83022.

Reynolds, R . . and White, C . , 1986, " T r a n s i t i o n M i x i n g T u r b i n e Engine Hot S e c t i o n Technoloqy 1983, NASA Study F i n a l R e p o r t . " NASA CR-175062. CP-2289.

T u r b i n e Enqine Hot S e c t i o n Technoloqy 1984, NASA R i z k , N . K . , and Mongia, H . C . , 1986, "Gas T u r b i n e Design CP-2339.

Methodology," A I A A Paper 86-1513.

T u r b i n e Engine Hot S e c t i o n Technoloqy 1985, NASA Roback, R . , and Johnson, B.V., 1983, "Mass and Momentum T u r b u l e n t T r a n s p o r t Experiments w i t h C o n f i n e d C o a x i a l CP-2405.

NASA CR-168252.

J e t s , " T u r b i n e Engine Hot S e c t i o n Technoloqy 1986, NASA Runchal, A k s a i , K . , Anand, M . S . , and Mongia. H . C . , CP-2444.

1987, "An U n c o n d i t i o n a l l y - S t a b l e C e n t r a l D i f f e r e n c i n g Scheme f o r High Reynolds Number Flows. A I A A Paper T u r b i n e Engine Hot S e c t i o n Technoloqy 1987, NASA CP-2493.

87-0060.

Sokolowski, D. E . , and Ensign, C . R . , 1986, "Toward Vanka, S . P . , 1987, " B l o c k - I m p l i c i t Computation o f

Viscous I n t e r n a l Flows - Recent R e s u l t s , " A I A A Paper

Improved D u r a b i l i t y i n Advanced Combustors and Turbines - Progress i n t h e P r e d i c t i o n o f Aerothermal 87-0058.

Loads." ASME Paper 86-GT-172. (NASA TM-88932).

R . , and Mongia, H . C . , 1980, "Numerical S r i n i v a s a n , Computations o f S w i r l i n g R e c i r c u l a t i n g Flow F i n a l Report." NASA CR-165196.

R . , B e r e n f e l d , A . , and Mongia, H . C . , 1982, S r i n i v a s a n , " D i l u t i o n J e t M i x i n g Program: Phase I Report," NASA CR-168031 .

S r i n i v a s a n , R . , Reynolds, R . , B a l l , I., B e r r y , R., Johnson, K . , and Mongia, H., 1983, "Aerothermal

M o d e l i n g Program: Phase I F i n a l R e p o r t - Volume I , "

NASA CR-168243.

S r i n i v a s a n , R . , Reynolds, R . , B a l l , I . , B e r r y , R . , Johnson, K . , and Mongia, H . , 1983, "Aerothermal Modeling Program: Phase I F i n a l Report - Volume 11."

VASA CR-168243.

S r i n i v a s a n , R . , Coleman, E., and Johnson, K . , 1984, " D i l u t i o n J e t M i x i n g Program: Phase I 1 Report," NASA CR-174624.

S r i n i v a s a n , R.. Meyers, G., Coleman, E . , and White, C.. 1985, " D i l u t i o n J e t M i x i n g Program: Phase I11 Report. " NASA CR-174884.

ORIGINAL PAGE I S

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HIGH SWIRL A I R EX11 AIR/REACTANT F I L M COOLING AIR' 0 FULLY 3 - D I E N S I O N A L F L O W 0 CHENICAL REACTION/HEAT RELEASE 0 HIGH TURBULENCE LEVELS 2 PHASE WITH VAPORIZATION FIGURE 1. - COMBUSTOR F L O W P H E N W N A .

CONFINED S T O I C H I W T R I C FLAK S T A B I L I Z E D ON A CYLINDRICAL F L A E H O L M R I N A RECTANGULAR DUCT PLUG FLOW REACTOR CUSHING ET AL ( 1 9 6 7 ) HAUTNAN E T AL (1981) /- ADIABATIC WALL P R -

t

PRENIXED - D = 10 cH -

-FUEL - A I R H

REACTANTS I PR 0 DUCTS

-

+ADIABATIC WALLS + CONCENTRIC FUEL AND 120 CH A I R JETS CONTAINED ' - H O L D E R 2-D CHANNEL F L O W I N A CYLINDRICAL COUETTE FLOW F L O W OVER A FLAT PLATE E E R Y AND GESSNER ( 1 9 7 6 ) COMBUSTOR E L TELBANY AND REYNOLDS (1982) WATTS AND BRUNDRETT ( 1979)

1 - L - 1

H I I

I

P I P E F L O W TWO STREAM N I X I N G LAYER DEVELOPING P I P E F L O W LAUFER (1953) S A l Y AND PEERLESS ( 1 9 7 8 ) BARBIN AND JONES (1963) FREE METHANE TURBULENT JET F L A K NASSAN E T AL (1980)

\

FLOW OVER A HEATED FLAT PLATE AXISYMmTRIC FREE JET CHARNAY E T AL ( 1 9 7 7 ) N I X I N G O F TWO COAXIAL JETS I N AMBIENT A I R WYGNANSKI AND FIELDER (1969) C H W A G N E AND WYGNANSKI (1970) TYPICAL A X I A L E A N VELOCITY PROFILE I N I-x 0.7 M F T W = 3 1 3 ' K + T H = 2 9 0 ° K j "AIR = ,o , , , $ TAIR = 293' K ( A ) SIMPLE FLOWS.

( 1 9 8 3 ) FIGURE 2. - FLOWS FOR WHICH ANALYTICAL NODEL CALCULATIONS WERE PERFORNED I N SRINIVASAN ET AL.

APL CWIBUSTION TUNNEL D = 13.87 4.77 m 4 F L O W I N A CURVED CHANNEL WEDGE-SHAPED SHIVA PRASAD AND R A M PRIYAN ( 1 9 7 8 ) CI AU A I K D A D A T Y Y A D n C A r l Y C D I A Y C CTCD L I KIH. KLINE, AND JOHNSTON ( 1 9 7 8 ) AND EATON AND JOHNSTON (1980) PEASUREPENT + * L O C A T I oNS 1 , l l L /IT n ‘ 0 I

- U

I INLET C I 1 - I - Y I I STRAIGHT R = 2.511 H C L - 1 SECT I ON FLOW OVER A RING I N A P I P E SUDDEN PIPE-EXPANSION PHATARAPHRUK AND LOGAN ( 1 9 7 9 ) NOON AND RUDINGER ( 1 9 7 7 ) .- I

7 R

I ON + X F L O W BEHIND A BACKWARD FACING STEP OPPOSED JET COMBUSTOR A X I S Y M T R I C COMBUSTOR WITH P I T 2 AND D A I L Y (1981) SCHEFFER AND SAWYER ( 1 9 7 6 ) COAXIAL FUEL AND A I R JETS ASBESTOS WCMl LEWIS AND W T ( 1 9 7 3 )

-. C W U T A T I O N /

REGION PROPANE t A I R (B) C W L E X NONSWIRLING FLOWS.

FIGURE 2. - CONTINUED.

SWIRL COMBUSTOR WITH COOLING A I R THO COAXIAL JETS I N STAGNANT A I R BRUM AND SAHUELSEN (1982)

m s E (1980)

i"7

.. ..

' A ALL D I E N S I O N S I N CM CONFINED SWIRL-DRIVEN F L O W CYLINDRICAL COMBUSTOR WITH ROTATING CUP ALTGELD, E T AL (1983) ATOMIZER AND A I R INTRODUCED THROUGH A SWIRLER

t - - - ' ) I SURROUNDING THE ATOMIZER

EL-BANHAWY AND HHITELAW (1981) lLLLu SWIRL t A I R CORE JET

'

e ALL D I E N S I O N S I N &

L I

I---- =-1

SWIRLING F L O W I N A P I P E EXPANSION JANJUA E T AL (1982) JI X I /

-LL

(C) SWIRLING FLOWS.

FIGURE 2. - CONCLUDED.

I 1 1 I I I I I 1 0 1 0 1 0 1 0 1 2 U-VELOCITY. n/s - REYNOLDS STRESS RODEL _ _ - ALGEBRAIC STRESS RODEL .....

K-E RODEL 0 DATA -.

:- _ _ u p - 1 I I I I I I 0 1 0 1 0 1 2 U-VELOCITY, u s - FIGURE 3. COMPARISON OF CLASURED E A N A X I A L VELOCITY PROFILES FOR COANNULAR JETS DOUNSTREM OF AN A X I S Y M T R I C SUDDEN EX- PANSION, WITH CALCULATIONS M A E USING THREE TURBULENCE RODELS.

PREDICTIONS W R V E N T S PREDICTIONS W R V L N T S PREDICTIONS E A S U R E E N T S W H = .5 WH = .75 W H = 1.0

-0.5 .5 I * -0.5 B .5 I *

-0.5 .5 -0.5 .5 -0.5 .5 -0.5 .5 TRANSVERSE DIST. Z/S WH = 0.75 W H = 1.00 W H = 0.50 t - y 40

pz,s

I- L

z/s = 0

PI z/s =

W I

b

7 . .

0 .20 . i o .60 .80 1.00 0 .20 ,110 .60 .80 1.V 0 .20 .40 .60 1.00 (RU\IN-T)/(RU\IN-TJ) FIGURE 4. - C W A R I S O N B E M E N EASURED AND CALCULATED D I E N S I O N L E S S TEWERATURE DIFFERENCE RATIOS WWWSTRW FROR A RW OF COOL JETS INJECTED INTO A CONSTANT-TEW'ERATURE CROSS F L O W FROR THE UPPER WALL OF A CONSTANT A R E A DUCT ( J = 25.32.

S/H = 0.25, H/D = 8. 1 9 890 NODES.

ORIGINAL PAGE 1 s

OF POOR QUALITY

PREDICTIONS E A S U R E E N T S PRED 1 CT 1 ONS E A S U R W N T S PREDlCTIONS I E A S U R W N T S W H = .5 WH = .75 WH = 1.0 sa I..

I \ >

z

- 4 I d 1.8

9 -0.5 .5 I.. -0.5 .5 -0.5 .5 @dB -0.5 .5 -0.5 B .5 -0.5 .5

TRANSVERSE D I S T . Z/S W H = 1-00 W H = 0.50 W H = 0.75

)i 2/s = 0

1',, z/s = 0 a 2/s = 0 w

- L

0 .20 .40 .60 .80 1.00 0 .20 .40 .60 .80 1.00 0 .20 .40 .60 .80 1.00 (TRAIN-T)/(TRAIN-TJ) FIGURE 5 . - COMPARISON BETWEEN KASURED AND CALCULATED DIEENSIONLESS TERERATURE DIFFERENCE RATIOS DOWNSTREPA FROM A R O W OF COOL JETS INJECTED INTO A CONSTANT-TEMPERATURE CROSS FLOW FROW THE UPPER WALL OF A CONSTANT AREA DUCT ( J = 25.32, S/H = 0.25. H I D = 8, 5615 NODES).

165 n

z, DE6 0 11.25 22.5

COMBUSTOR SECTOR END VIEW xnA 11.48 2.08 10.46 I 1 6 11 16 21 26 31 37

0.0 10.0287 )0.0658 l0.0993 I

0.23

’” 0.0144 0.047 0.0803 0.138

W I C I I V I P M R HA = 15.768 KG/S P3 = 1085.3 KPA T3 = 609.4 K FAR = 0.0225 FIGURE 6. - ANNULAR COMBUSTOR SCHEMTIC AND CALCULATION GRID CONFIGURATION.

I DF-2 . . ..

.

0 PREDICTION A DATA 1 0 DF-2 !

4 ' -

-._I.--....-.--..

2 .

-7- - 1 - t .10 .15 .20 .25 .30 FUEL/AIR RATIO FUEL/AIR RATIO (E) CMBUSTION EFFICIENCY.

( B ) UNBURNED HYDROCARBONS.

1.0 I DF-2 I .___________.____________I . .

A '-4 ...._.----I..---.-.- . . . . . . . . . . __ q 8 1 - II L

. . . . . . . . . . . . . . . . . --

q " 0 .10 -15 .20 .25 . 3 0 FUEL/AIR RATIO (C) OXIDES OF NITROGEN.

-20 .25 -30 -35 FUEL/AIR RATIO ' A p 3 l p 3 (D) SOOT.

(G) LEAN BLOWOUT CHARACTERISTICS.

FIGURE 7. - C W A R I S O W OF lEASURED AND PREDICTED PERFORMNCE AND EMSSlONS FOR CMBUSTOR I N F16. 6.

K = 2 3 K = l 4 A K = 5 A d (A) FLOW SCHEMATIC.

DRIVEN CAVITY

00 /

X I I I I I 500' 0 .04 .08 .12 .16 .20 DISTANCE. n FIGURE 8. - CALCULATED LINER WALL TEH-

* 2 I-

PERATURES AT R4XIMUN POWER CONDITION FOR COMBUSTOR I N F I G . 6.

-0.50 -0.25 0 .25 .50 .75 1.00 U (B) VELOCITY PROFILES AT SECTION A-A.

- CALCULATIONS OF L M I N A R FLOW I N A SQUARE FIGURE 9.

(2-D) DRIVEN CAVITY.

Z/D = .04 0.02 1.04 1.45 2.08 3.10 6.20 12.45 F L O W CONTROL EACH P R I M R Y H - Vzflz. c (B) PARTICLE A X I A L VELOCITY.

-- IS 0 IN - 4

F L O W CONTROL VALVE FIGURE 10. - TEST SECTION G E W T R Y FOR E X P E R I E N T A L STUDY O F I N - TERACTION B E N E N F L O W FROn MULTIPLE SWIRLERS AND TRANSVERSE JETS.

N/Nc (C) PARTICLE NUMBER DENSITY.

FIGURE 11. - RADIAL PROFILES OF GAS-AND SOLID-PHASE E A N F L O W C W O N E N T S AND PARTICLE NUHBER DENSITY AT A PARTI- CLE NUMBER DENSITY AT A PARTICLE-TO-GAS MASS LOADING RATIO OF 1.0.

N89-20139

REVIEW AND ASSESSMENT OF THE DATABASE AND NUMERICAL MODELING FOR TURBINE H E A T TRANSFER H. J. Gladden and R. J. Simoneau National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio gas stream p r e s s u r e ABSTRACT r a d i u s The o b j e c t i v e s o f t h e HOST T u r b i n e Heat T r a n s f e r s u b p r o j e c t were t o o b t a i n a b e t t e r u n d e r s t a n d i n g o f t h e s t a t o r e x i t Reynolds number p h y s i c s o f t h e aerothermodynamic phenomena and t o assess and improve t h e a n a l y t i c a l methods used t o p r e d i c t t h e l o c a l Reynolds number f l o w and h e a t t r a n s f e r i n h i g h - t e m p e r a t u r e gas t u r b i n e s .

A t t h e t i m e t h e HOST p r o j e c t was i n i t i a t e d , an across- c o o l a n t temperature the-board improvement i n t u r b i n e d e s i g n t e c h n o l o g y was needed. A b u i l d i n g - b l o c k approach was u t i l i z e d and t h e gas stream temperature r e s e a r c h ranged f r o m t h e s t u d y o f fundamental phenomena and m o d e l i n g t o e x p e r i m e n t s i n s i m u l a t e d r e a l engine a i r f o i l temperature environments. Experimental r e s e a r c h accounted f o r a p p r o x i m a t e l y 75 p e r c e n t o f t h e f u n d i n g w h i l e t h e ana- t u r b u l e n c e i n t e n s i t y l y t i c a l e f f o r t s were a p p r o x i m a t e l y 2 5 p e r c e n t . A h e a l t h y g o v e r n m e n t l i n d u s t r y l u n i v e r s i t y p a r t n e r s h i p , w i t h s u r f a c e d i s t a n c e i n d u s t r y p r o v i d i n g a l m o s t h a l f o f t h e r e s e a r c h , was c r e a t e d t o advance t h e t u r b i n e h e a t t r a n s f e r d e s i g n S t a n t o n number t e c h n o l o g y base.

r e f e r e n c e S t a n t o n number NOMENCLATURE gas stream v e l o c i t y a i r f o i l a x i a l c h o r d B X rotor wheel speed C b l a d e t i p gap moving s u r f a c e v e l o c i t y a x i a l flow speed C X i n s t a n t a n e o u s v e l o c i t y D j e t d i a m e t e r l b l a d e t i p c a v i t y d e p t h c o o l a n t v e l o c i t y d c o o l a n t channel h y d r a u l i c d i a m e t e r b l a d e t i p c a v i t y w i d t h H h e a t t r a n s f e r c o e f f i c i e n t a x i a l l e n g t h Ho r e f e r e n c e h e a t t r a n s f e r c o e f f i c i e n t a n g l e between mean v e l o c i t y and m a j o r t i p c a v i t y s t a t o r e x i t Mach number M2 a x i s Nu Nussel t number l e n g t h s c a l e r e f e r e n c e Nussel t number Nu0 r o t a t i o n a l v e l o c i t y c o o l a n t p r e s s u r e P C INTRODUCTION T h i s paper o u t l i n e s t h e program d i r e c t e d a t these g o a l s . The paper w i l l d e l i n e a t e p r o g r e s s towards t h e Improved performance o f a i r c r a f t gas t u r b i n e g o a l s by r e p o r t i n g example r e s u l t s f r o m each o f t h e engines i s t y p i c a l l y accompanied by i n c r e a s e d c y c l e v a r i o u s r e s e a r c h a c t i v i t i e s . I t w i l l summarize t h e p r e s s u r e r a t i o and combustor e x i t gas t e m p e r a t u r e . The major accomplishments and w i l l make some o b s e r v a t i o n s h o t - s e c t i o n components o f these t u r b o j e t l t u r b o f a n on f u t u r e needs.

engines a r e s u b j e c t e d t o severe a e r o t h e r m a l l o a d s d u r i n g TURBINE HEAT TRANSFER SUBPROJECT t h e m i s s i o n f l i g h t p r o f i l e . M e e t i n g t h e d e s i g n g o a l s o f h i g h c y c l e e f f i c i e n c y , i n c r e a s e d d u r a b i l i t y o f t h e h o t - s e c t i o n components, and lower o p e r a t i n g c o s t s r e q u i r e s a The r e s e a r c h program o f t h e T u r b i n e Heat T r a n s f e r m u l t i d i s c i p l i n a r y approach. T u r b i n e Heat T r a n s f e r was S u b p r o j e c t was based on t h e i d e a t h a t an a c r o s s - t h e - board improvement i n t u r b i n e d e s i g n was needed. I t was one o f t h e s i x d i s c i p l i n e s addressed i n t h e m u l t i d i s c i - p l i n a r y Hot S e c t i o n Technology (HOST) P r o j e c t . a l s o based on an o v e r a l l p h i l o s o p h y a t NASA Lewis Research C e n t e r o f t a k i n g a b u i l d i n g b l o c k approach t o When t h e HOST P r o j e c t was o r i g i n a l l y b e i n g p l a n n e d , Stepka (1980). one o f t h e o r i g i n a t o r s o f t h e p r o j e c t , t u r b i n e h e a t t r a n s f e r , as shown i n F i g . 3 . The r e s e a r c h ranged f r o m t h e s t u d y o f fundamental phenomena and mod- p e r f o r m e d an u n c e r t a i n t y a n a l y s i s on t h e a b i l i t y t o p r e - d i c t t u r b i n e a i r f o i l temperatures. He e s t i m a t e d t h a t e l i n g t o experiments i n r e a l e n g i n e environments. B o t h t h e t h e n c u r r e n t a b i l i t y t o p r e d i c t m e t a l t e m p e r a t u r e i n e x p e r i m e n t a l and a n a l y t i c a l r e s e a r c h were conducted.

an o p e r a t i n g engine was w i t h i n 100 K and t h a t by t e s t i n g R e t u r n i n g t o F i g s . 1 and 2 , t h e range o f phenomena p r o t o t y p e s t h i s c o u l d be r e f i n e d t o w i t h i n 50 K . He addressed i n t h e T u r b i n e Heat T r a n s f e r S u b p r o j e c t a r e a l s o suggested t h a t t h e u n c e r t a i n t y i n h e a t f l u x was on i d e n t i f i e d by numbers and arrows on these f i g u r e s . The t h e e x t e r n a l o r t h e h o t gas s i d e s u r f a c e o f t h e a i r f o i l c o r r e s p o n d i n g r e s e a r c h programs a r e i d e n t i f i e d i n was a p r i n c i p l e c o n t r i b u t o r t o t h e i n a b i l i t y t o p r e d i c t Tables 1 and 2 . One can see f r o m t h e s e f i g u r e s t h a t t h e metal t e m p e r a t u r e s ; however, b o t h i n t e r n a l and e x t e r n a l T u r b i n e Heat T r a n s f e r S u b p r o j e c t covered m o s t o f t h e key s u r f a c e h e a t t r a n s f e r were i m p o r t a n t . These l e v e l s o f h e a t t r a n s f e r p o i n t s on t h e t u r b i n e a i r f o i l : f i l m u n c e r t a i n t y i n metal t e m p e r a t u r e can c o n t r i b u t e t o an c o o l e d a i r f o i l s , passage c u r v a t u r e , endwall f l o w s , t r a n - o r d e r o f magnitude u n c e r t a i n t y i n component l i f e . s i t i o n i n g b l a d e boundary l a y e r s , t i p r e g i o n s , and f r e e - A t y p i c a l c o o l e d a i r c r a f t gas t u r b i n e b l a d e i s stream t u r b u l e n c e on t h e e x t e r n a l s u r f a c e s . The i l l u s t r a t e d i n F i g . 1 , showing t h e i n t r i c a t e i n t e r n a l s u b p r o j e c t i n c l u d e d impingement and t u r b u l a t e d serpen- flow passages and t h e v a r i e t y o f h e a t t r a n s f e r mecha- t i n e passages on t h e i n t e r n a l s u r f a c e s . The program work. These i n c l u d e : impingement c o o l i n g , nisms a t b r o k e some new ground. An e x p e r i m e n t was conducted, s e r p e n t i n e passages w i t h t u r b u l a t o r s u r f a c e s , and p i n which o b t a i n e d h e a t t r a n s f e r d a t a on t h e s u r f a c e s o f t h e f i n s , a l l i n v e r y s h o r t ( i . e . , e n t r a n c e l e n g t h ) d i s - a i r f o i l s i n a one and o n e - h a l f stage l a r g e low speed t a n c e s and s u b j e c t t o s t r o n g r o t a t i o n a l f o r c e s . I n r o t a t i n g t u r b i n e . Another e x p e r i m e n t a c q u i r e d d a t a on f i l m c o o l e d , t h e i n t e r - t o a d d i t i o n , s i n c e most b l a d e s a r e t h e i n t e r n a l t u r b u l a t e d s e r p e n t i n e passages s u b j e c t n a l mass b a l a n c e i s a v a r i a b l e . The c o m p l e x i t y of t h e r o t a t i o n a t e n g i n e c o n d i t i o n l e v e l s . F i n a l l y , vane h e a t e x t e r n a l flow f i e l d o v e r t h e t u r b i n e b l a d e i s i l l u s - t r a n s f e r d a t a were a c q u i r e d i n a r e a l e n g i n e t y p e e n v i - t r a t e d i n F i g . 2 . Heat t r a n s f e r i n t h e e x t e r n a l f l o w ronment b e h i n d an a c t u a l o p e r a t i n g combustor.

i s c h a r a c t e r i z e d b y : h i g h Reynolds number f o r c e d HOST P r o j e c t a l i t t l e l e s s f i e l d Over t h e l i f e o f t h e c o n v e c t i o n w i t h r o t a t i o n , h i g h f r e e - s t r e a m t u r b u l e n c e , t h a n 5 . 5 m i l l i o n n e t r e s e a r c h d o l l a r s were i n v e s t e d i n t h e T u r b i n e Heat T r a n s f e r S u b p r o j e c t . A s shown i n s t r o n g p r e s s u r e and temperature g r a d i e n t s , s u r f a c e c u r - v a t u r e , and an unsteady f l o w f i e l d . I n a d d i t i o n , and F i g . 4 ( a ) , t h e r e was a h e a l t h y g o v e r n m e n t l i n d u s t r y l most i m p o r t a n t , t h e i n t e r n a l and e x t e r n a l s u r f a c e h e a t u n i v e r s i t y p a r t n e r s h i p w i t h i n d u s t r y p r o v i d i n g a l m o s t t r a n s f e r c o e f f i c i e n t s a r e c o u p l e d t h r o u g h t h e metal h a l f t h e r e s e a r c h e f f o r t . A p p r o x i m a t e l y t h r e e - f o u r t h s w a l l s . I n f a c t , t h e t u r b i n e a i r f o i l i s a v e r y compact, o f t h e e f f o r t was e x p e r i m e n t a l , as shown i n F i g . 4 ( b ) .

v e r y complex, and v e r y e f f i c i e n t h e a t exchanger. T h i s The m a j o r i t y o f e f f o r t e s t a b l i s h e d a l a r g e number o f f e a t u r e i s p a r t i c u l a r l y i m p o r t a n t i n a d u r a b i l i t y pro- major e x p e r i m e n t a l d a t a s e t s . These d a t a s e t s have been gram, such as HOST, where t h e r e a l f o c u s i s on t h e t h e r - w e l l r e c e i v e d and a r e expected t o p r o v i d e benchmarks o f t h e s t r u c t u r a l elements. f o r t u r b i n e h e a t t r a n s f e r for many y e a r s t o come.

mal s t r e s s and f a t i g u e The a n a l y s e s covered a wide range, i n c l u d i n g a t h r e e - Thus, i n t h e HOST T u r b i n e Heat T r a n s f e r S u b p r o j e c t i t was i m p o r t a n t t o d i r e c t r e s e a r c h a t t e n t i o n t o b o t h dimensional Navier-Stokes e f f o r t ; however, most o f t h e t h e i n t e r n a l and e x t e r n a l s u r f a c e s o f t h e t u r b i n e a n a l y t i c e f f o r t was f o c u s e d on m o d e l i n g l o c a l phenomena a i r f o i 1 . o f key i m p o r t a n c e . The scope and range o f t h e program I n t h e m u l t i d i s c i p l i n a r y HOST P r o j e c t each p a r t i c - i s b e s t seen by examining r e p r e s e n t a t i v e r e s u l t s .

i p a t i n g d i s c i p l i n e s e l e c t e d i t s own o b j e c t i v e based on EXPERIMENTAL DATABASE t h e g r e a t e s t need i n t h a t p a r t i c u l a r area, r a t h e r t h a n some common i n t e r d i s c i p l i n a r y g o a l . I n T u r b i n e Heat The e x p e r i m e n t a l p a r t o f t h e T u r b i n e Heat T r a n s f e r Transfer i t was decided, based on e v a l u a t i o n s o f t h e S u b p r o j e c t c o n s i s t e d of s i x (6) l a r g e e x p e r i m e n t s and t y p e p e r f o r m e d by Stepka (1980), t h a t an across-the- board improvement i n t u r b i n e h e a t t r a n s f e r t e c h n o l o g y t h r e e ( 3 ) o f somewhat more modest scope and was s t r u c - A r a t c h e t i n g up o f t h e o v e r a l l t e c h n o l o g y ; t u r e d to address t h e phenomena i d e n t i f i e d i n F i g s . 1 was needed.

a moving f r o m a c o r r e l a t i o n base t o a more a n a l y t i c a l and 2 . Three ( 3 ) o f t h e l a r g e e x p e r i m e n t s were con- base was i d e n t i f i e d as t h e T u r b i n e Heat T r a n s f e r Sub- ducted i n a s t a t i o n a r y frame o f r e f e r e n c e and t h r e e ( 3 ) p r o j e c t g o a l . I t was a l s o i d e n t i f i e d t h a t t h e e x i s t i n g were conducted i n a r o t a t i n g frame o f r e f e r e n c e .

d a t a base was i n s u f f i c i e n t t o s u p p o r t t h i s m v e m e n t and i n c r e a s i n g b o t h t h e s i z e and q u a l i t y o f t h e d a t a base S t a t i o n a r y Reference I t was f u r t h e r r e c o g n i z e d t h a t HOST One o f t h e i n i t i a l r e s e a r c h e f f o r t s was t h e s t a t o r was e s s e n t i a l .

a i r f o i l h e a t t r a n s f e r program performed a t t h e A l l i s o n a l o n e c o u l d n o t achieve t h i s g o a l . It was hoped t h a t Gas T u r b i n e D i v i s i o n (Nealy e t a l . , 1983; H y l t o n e t a l . , HOST c o u l d be a s u f f i c i e n t c a t a l y s t and p r o v i d e a s u f - f i c i e n t f o r u m t o make t h i s goal one t h a t a l l o f t h e 1983; Nealy e t a l . , 1984; Turner e t a l . , 1985; Yang e t a l . , 1985). T h i s r e s e a r c h c o n s i s t e d o f d e t e r m i n i n g t h e p a r t n e r s ; government, i n d u s t r y and u n i v e r s i t i e s ; would e f f e c t s of Reynolds number, t u r b u l e n c e l e v e l , Mach f i n d o b t a i n a b l e and w o r t h p u r s u i n g .

number, temperature ratio, acceleration, and bound- Typical results are shown in Fiy. 7 for thin film ary layer transition o n heat transfer coefficients for thermocouples and the dynamic gas temperature probe tested a simulated real engine condition. A comparison various airfoi 1 geometries at simulated engine condi- f l u x measurements and tions. This research was conducted for nonfilm-cooled is made between steady state heat airfoils, showerhead film-cooled designs and showerhead/ those determined from dynamic signal analysis gill-region film cooling concepts. Typical results of techniques.

Stanford University has conducted a systematic this research are shown in Fig. 5. A typical cascade of the physical phenomena that affect heat trans- study configuration is shown in the photograph (Fig. 5(a)).

fer in turbine airfoil passages. Their recent experi- Two-dimensional midspan heat transfer coefficients and static pressure distributions were measured on the cen- mental research has been concerned with high free-stream turbulence intensity and large turbulence scale that tral airfoil of the three vane cascade. Nonfilm-cooled might be representative of combustor exit phenomena. A data are shown in Fig. 5(b) where the boundary layer schematic of their free jet test facility and typical transition is clearly identified as a function of results are shown in Fig. 8. Data are measured on a Reynolds number on the suction surface. Figure 5(c) constant temperature flat plate located at a specified shows the effect on heat transfer in the downstream radial and axial distance from the jet exit centerline.

recovery region to the addition of showerhead film cool- These data, presented as Stanton number ratios, indicate ing. Data are presented as a Stanton number reduction.

high as 5X at A detrimental effect is noted in the boundary layer that heat transfer augmentation can be as a high value of free-stream turbulence intensity but transition region of the suction surface to the addition if the length scale is changed. These results mass at the leading edge. only 3X Figure 5(d) shows a strong suggest that the designer must know a great deal more dependence on "gill-region" film cooling which is con- about the aerodynamic behavior of the flow field in sistent with experience.

However, when combining order to successfully predict the thermal performance showerhead with gill-region film cooling more mass addi- of the turbine components.

tion is not always better as indicated by the Stanton Prior to the advent of the HOST program, Arizona number reduction data on the pressure surface. This is State University was pursuing a systematic study of a very extensive dataset which systematically shows the impingement heat transfer with cross-flow characteristic important effects of modern film cooling schemes on mod- of turbine airfoil cooling schemes. The work was ini- ern airfoils. It went beyond the traditional effective- tially sponsored by a NASA Lewis grant but was subse- ness correlations to provide actual heat transfer data.

quently funded by the HOST program. The results of this It should provide a valuable baseline for emerging anal- research are summarized in Florschuetz et al. (1982a), ysis codes.

Florschuetz et al. (1982b). Florschuetz et al. (1982c), An investigation of secondary flow phenomena i n a Florschuetz et al. (1983). Richards et al. (1984), 90° curved duct was conducted at the University of Florschuetz et a1 (1984). Florschuetz et al. (1987).

Tennessee Space Institute (Crawford et al, 1985). The Florschuetz et al. (1985), Florschuetz et al. (1984).

curved duct was utilized to represent airfoil passage In addition to the many geometry variations, this curvature without the complexity of the horseshoe research also investigated the effects of various jet- vortex. These data consist of simultaneous three- flow to crossflow ratios and differences between the dimensional mean value and fluctuating components of jet-flow and the cross-flow temperature. Correlatfons velocity through the duct and compliment similar data inline rows of impingement jets in the literature. A schematic of the test facility were developed for both and staggered arrays of jets but without an initial and the three-dimensional laser velocimeter are shown The effects of cross-flow and temperature in Fig. 6 . The first phase of the research examined cross-flow.

differences were then determined relative to the base flows with a relatively thin inlet boundary layer and low free-stream turbulence. The second phase studied a correlations.

thicker inlet boundary layer and higher free-stream tur- bulence. Typical experimental results of this research Rotating Reference In the rotating reference frame, experimental aero- are shown in Fig. 6 . The vector plot of cross-flow vel- ocities clearly shows the development of a vortex i n the dynamic and heat transfer measurements were made in the large, low-speed turbine at the United Technologles duct corner near the low pressure surface. The analyt- ical results will be mentioned in the Viscous Flow Research Center (Dring et al., 1987; Dring et al., 1986a; Dring et a l . , 1986b; Dring et al., 1986c; Blair Analysis section. These data provide a comprehensive 1988; Blair et al., 1988). Single-stage data et al., benchmark to verify codes at realistic flow conditions.

with both high and low-inlet turbulence were taken in Two experiments were also conducted at NASA Lewis I. The second phase examined a one and one-half phase in the high-pressure facility (Gladden et al., 1985a; stage turbine and focused on the second vane row. Under

Gladden et al., 1985b; Gladden et al., 1987;.Hippen-

1 1 1 aerodynamic quantities such as interrow time- 1985). This facility was capable of phase steele et a l . , averaged and rms values of velocity, flow angle, inlet testing a full-sized single-stage turbine at simulated turbulence, and surface pressure distributions were real engine conditions. The tests, however, were lim- measured. A photograph of the test facility is shown in ited to combined combustor/stator experiments.

One 9. Typical heat transfer data for both the first Fig.

experiment examined full-coverage fi lm-cooled stator stator and rotor are also shown. These data show that airfoils, while the second experiment utilized some of of inlet turbulence has a substantial impact an increase the advanced instrumentation developed under the instru- o n the first stator heat transfer. However, the impact mentation subproject. A comparison of experimental air- on the rotor heat transfer is minimal. These data are

foil temperatures with temperatures obtained from a

also compared with Stanton numbers calculated by a typical design system showed substantial differences for boundary layer code and the assumption that the boundary the full-coverage, film-cooled airfoils and suggests layer was either laminar (LAM) or fully turbulent that models derived from low-temperature experiments are (TURB). These assumptions generally bracketed the data inadequate for "real-engine'' conditions. The advanced on the suction surface of both the stator and the rotor.

instrumentation tests demonstrated the capabi 1 i ty and However, the heat transfer on the pressure surface, the challenges of measuring heat flux and time-resolved especially for the high turbulence case, was generally gas temperature fluctuation in a real-engine above even fully turbulent levels on both airfoils.

environment.

Pressure surfaces have traditionally received less a t t e n t i o n than s u c t i o n s u r f a c e s . The h i g h h e a t t r a n s - d a t a i n t h e l i t e r a t u r e . S p e c i f i c recommendations a r e f e r on t h e p r e s s u r e s u r f a c e i s n o t r e a d i l y e x p l a i n a b l e made t o improve t u r b i n e a i r f o i l h e a t t r a n s f e r modeling and c a l l s for a d d i t i o n a l r e s e a r c h , e s p e c i a l l y m o d e l i n g , u t i l i z i n g a boundary l a y e r a n a l y s i s . These recommen- on p r e s s u r e surfaces.

d a t i o n s address t h e boundary c o n d i t i o n s , t h e i n i t i a l The t i p r e g i o n o f r o t o r b l a d e s i s o f t e n a c r i t i c a l c o n d i t i o n s p e c i f i c a t i o n , i n c l u d i n g b o t h v e l o c i t y and from r e g i o n and an a r e a t h a t s u f f e r s s u b s t a n t i a l damage thermal p r o f i l e s , and m o d i f i c a t i o n s o f c o n v e n t i o n a l t h e h i g h temperature environment. A r i z o n a S t a t e z e r o o r d e r t u r b u l e n c e models. The r e s u l t s o f these U n i v e r s i t y has e x p e r i m e n t a l l y modeled t h e b l a d e t i p improvements a r e shown i n F i g . 12 where t h e s t a r t o f c a v i t y r e g i o n and d e t e r m i n e d h e a t t r a n s f e r r a t e s by a t r a n s i t i o n and i t s e x t e n t on t h e s u c t i o n s u r f a c e a r e mass t r a n s f e r a n a l o g y w i t h n a p h t h y l e n e (Chyu e t a i . , r e a s o n a b l y w e l l c h a r a c t e r i z e d . For t h e case o f shower- A schematic o f t h e t e s t i s shown i n F i g . 10.

1987). head f i l m c o o l i n g , two e m p i r i c a l c o e f f i c i e n t s were u t i - The b l a d e t i p c a v i t y i s a s t a t i o n a r y model and t h e l i z e d t o m o d i f y t h e f r e e - s t r e a m t u r b u l e n c e i n t e n s i t y and r e l a t i v e v e l o c i t y o f t h e shroud i s r e p r e s e n t e d by a t h e gas s t r e a m e n t h a l p y boundary c o n d i t i o n s and p e r m i t a moving s u r f a c e a t a s p e c i f i e d "gap" s p a c i n g f r o m t h e r e p r e s e n t a t i v e p r e d i c t i o n o f t h e S t a n t o n number reduc- b l a d e . S t a n t o n number r e s u l t s f o r two d i f f e r e n t c a v i t y t i o n i n t h e r e c o v e r y r e g i o n . Boundary l a y e r methods can a s p e c t r a t i o s a r e a l s o shown i n F i g . 10. The h e a t be used f o r midspan a n a l y s i s , however t h e y r e q u i r e a t r a n s f e r on t h e s u r f a c e s n e x t t o t h e shroud a r e l i t t l e r e a l i s t i c d a t a base t o p r o v i d e t h e c o e f f i c i e n t s needed changed by t h e a s p e c t r a t i o which i s n o t s u r p r i s i n g . for p r o p e r r e f e r e n c e .

I n a n o t h e r boundary l a y e r code e f f o r t U n i t e d Tech- However, t h e h e a t t r a n s f e r t o t h e f l o o r o f t h e c a v i t y i s i n c r e a s e d s i g n i f i c a n t l y on t h e downstream p o r t i o n a t n o l o g i e s Research Center assessed t h e a p p l i c a b i l i t y o f t h e l o w e r a s p e c t r a t i o . Also shown i n t h e f i g u r e i s t h e i t s three-dimensional boundary l a y e r code t o c a l c u l a t e f l o w a n g l e e f f e c t on h e a t t r a n s f e r . Because o f t h e a i r - h e a t t r a n s f e r t o t a l p r e s s u r e l o s s and s t r e a m l i n e f l o w f o i l t u r n i n g a t t h e t i p t h e c a v i t y w i l l be a t d i f f e r e n t p a t t e r n s i n t u r b i n e passages. The r e s u l t s i n d i c a t e a angles o f a t t a c k t o t h e mean c r o s s f l o w d i r e c t i o n . The s t r o n g t h r e e - d i m e n s i o n a l e f f e c t on a t u r b i n e b l a d e , and d a t a shows a m i n i m a l e f f e c t a t an a s p e c t r a t i o o f 0 . 9 agrees q u a l i t a t i v e l y w i t h e x p e r i m e n t a l d a t a . The same and a s u b s t a n t i a l e f f e c t a t an a s p e c t r a t i o o f 0 . 2 3 . code was m o d i f i e d f o r use as a two-dimensional unsteady T h i s d a t a s e t i s r e a l l y q u i t e a new a d d i t i o n t o a t r a d i - code i n o r d e r t o analyze t h e r o t o r - s t a t o r i n t e r a c t i o n t i o n a l l y n e g l e c t e d a r e a and shows t h a t w i t h c a r e f u l phenomena ( V a t s a , 1985; Anderson e t a l . , 1985a; Anderson d a t a s e t s and a n a l y s e s one can o b t a i n an o p t i m a l d e s i g n e t a l . , 1985b; Anderson, 1 9 8 5 ~ ) . These codes a l s o for t i p c a v i t i e s . needed d a t a as i n p u t .

The p r e c e e d i n g s t u d i e s were f o c u s e d on t h e hot-gas F i n a l l y , a fundamental s t u d y on n u m e r i c a l t u r b u - s i d e phenomena. S i n c e t h e h e a t t r a n s f e r phenomena i s l e n c e modeling, d i r e c t e d s p e c i f i c a l l y a t t h e a i r f o i l i n d r i v e n by t h e hot-gas s i d e c o n d i t i o n s , i t i s a p p r o p r i a t e t h e t u r b i n e environment, was conducted a t t h e U n i v e r s i t y t o c o n c e n t r a t e r e s o u r c e s on t h i s a r e a . However, t h e o f Minnesota. A m o d i f i e d form of t h e Lam-Bremhorst low- c o o l a n t - s i d e h e a t t r a n s f e r i s a l s o i m p o r t a n t . There- Reynolds-number k-e t u r b u l e n c e model was developed t o f o r e , c o o l a n t passage h e a t - t r a n s f e r and flow measure- p r e d i c t t r a n s i t i o n a l boundary l a y e r f l o w s under c o n d i - ments i n a r o t a t i n g r e f e r e n c e frame were a l s o o b t a i n e d t i o n s c h a r a c t e r i s t i c o f gas t u r b i n e b l a d e s (Schmidt a t P r a t t & Whitney A i r c r a f t / U n i t e d Technologies Research e t a l . , 1987) i n c l u d i n g b o t h f r e e - s t r e a m t u r b u l e n c e and Center (Kopper. 1984; S t u r g e s s e t a l . , 1987; L o r d p r e s s u r e g r a d i e n t .

e t a l . , 1987). E x p e r i m e n t a l d a t a were o b t a i n e d f o r The purpose was t o e x t e n d p r e v i o u s work on t u r - smooth-wall s e r p e n t i n e passages and for s e r p e n t i n e pas- bulence m o d e l i n g t o a p p l y t h e model t o t r a n s i t i o n a l sages w i t h skewed and normal t u r b u l a t o r s . The flow and f l o w s w i t h b o t h f r e e - s t r e a m t u r b u l e n c e and p r e s s u r e r o t a t i o n c o n d i t i o n s were t y p i c a l o f those f o u n d i n g r a d i e n t s . The r e s u l t s o f t h e e f f o r t a r e compared with a c t u a l engines. T h i s was a v e r y r e a l i s t i c e x p e r i m e n t . t h e e x p e r i m e n t a l d a t a o f A l l i s o n Gas T u r b i n e D i v i s i o n Data for b o t h t h e smooth-wall and skewed t u r b u l a t o r pas- i n F i g . 13. The augmentation o f h e a t t r a n s f e r on t h e sages a r e shown i n F i g . 1 1 f o r r a d i a l o u t f l o w , r e p r e - p r e s s u r e s u r f a c e o v e r t h e f u l l y t u r b u l e n t v a l u e i s pre- s e n t i n g o n l y a t i n y f r a c t i o n of t h e t o t a l d a t a i n v o l v e d d i c t e d r e a s o n a b l y w e l l . I n a d d i t i o n , when an adverse i n t h i s v e r y complex flow. 80th d a t a s e t s a r e shown p r e s s u r e g r a d i e n t c o r r e c t i o n i s u t i l i z e d , t h e s u c t i o n c o r r e l a t e d w i t h t h e r o t a t i o n number e x c e p t for h i g h s u r f a c e h e a t t r a n s f e r d a t a i s a l s o p r e d i c t e d r e a s o n a b l y r o t a t i o n numbers on t h e h i g h p r e s s u r e s u r f a c e . T h i s i s w e l l .

an a r e a t h a t r e q u i r e s a d d i t i o n a l r e s e a r c h t o u n d e r s t a n d T h i s was a r e a s o n a b l y good b e g i n n i n g t o estab- and model t h e p h y s i c a l phenomena o c c u r r i n g i n these l i s h i n g a methodology for moving away f r o m t h e heavy passages. dependence on e m p i r i c a l c o n s t a n t s . A l t h o u g h boundary l a y e r methods w i l l never s o l v e t h e whole problem, t h e y ANALYTICAL TOOLS w i l l always remain i m p o r t a n t a n a l y t i c t o o l s .

The a n a l y t i c p a r t s o f t h e t u r b i n e h e a t t r a n s f e r Viscous Flow A n a l y s i s s u b p r o j e c t a r e c h a r a c t e r i z e d by e f f o r t s t o adapt e x i s t - The t h r e e - d i m e n s i o n a l Navier-Stokes TEACH code has I n i n g codes and a n a l y s e s t o t u r b i n e h e a t t r a n s f e r . been m o d i f i e d by P r a t t & Whitney f o r a p p l i c a t i o n t o g e n e r a l , these codes and analyses were w e l l e s t a b l i s h e d i n t e r n a l passages and to i n c o r p o r a t e r o t a t i o n a l terms.

b e f o r e HOST became i n v o l v e d ; however, t h e a p p l i c a t i o n s The m o d i f i e d code has been d e l i v e r e d t o NASA Lewis and for t u r b i n e h e a t t r a n s f e r , and e x t e n s i v e r e v i - t e s t e d on some s i m p l e g e o m e t r i c cases. The r e s u l t s o f were n o t t h i s e f f o r t i n d i c a t e t h a t t h e code i s q u a l i t a t i v e l y s i o n has o f t e n been r e q u i r e d . I n some cases t h e ana- adequate for s i m p l e geometries. For geometries o f l y t i c and e x p e r i m e n t a l work w e r e p a r t o f t h e same p r a c t i c a l i n t e r e s t , much work remains t o be done t o c o n t r a c t .

b r i n g t h e i n t e r n a l passage c o m p u t a t i o n a l codes up t o t h e l e v e l o f p r o f i c i e n c y o f t h e f r e e - s t r e a m codes. For Boundary Layer A n a l y s i s t h e e x t e r n a l a i r f o i l s u r f a c e i m p o r t a n t a n a l y t i c p r o g r e s s The STAN5 boundarv-laver code ( C r a w f o r d e t a l . .

i s b e i n g made. By c o n t r a s t , t h e work on i n t e r n a l pas- 1976) ( w h i c h was develbped-on NASA c o n t r a c t a t S t a n f o r d i s s t i l l p r i m i t i v e . The i n t e r n a l p r o b l e m i s sub- U n i v e r s i t y i n t h e mid-1970's) was m o d i f i e d by A l l i s o n sages Gas T u r b i n e D i v i s i o n t o d e f i n e s t a r t i n g p o i n t s and s t a n t i a l l y more complex.

A f u l l y e l l i p t i c three-dimensional Navier-Stokes t r a n s i t i o n l e n g t h o f t u r b u l e n t flow t o accommodate t h e i r d a t a , w i t h and w i t h o u t f i l m c o o l i n g , as w e l l as code has been under development a t S c i e n t i f i c Research A s s o c i a t e s ( S R A ) f o r many y e a r s . T h i s code was p r i m a r - 9. A f u l l y e l l i p t i c Navier-Stokes code was d e v e l - i l y d i r e c t e d a t i n l e t s and n o z z l e s . S R A , I n c . , has oped f o r t u r b i n e a i r f o i l s and i n c l u d e s t u r b u l e n c e model- for t u r b i n e a p p l i c a t i o n s (Weinberg m o d i f i e d t h e code i n g , an energy e q u a t i o n and improved u s e r f r i e n d l i n e s s .

e t a l . , 1985). T h i s i n c l u d e s g r i d work for t u r b i n e a i r - F r e q u e n t l y , h e a t t r a n s f e r i s a l i m i t i n g f a c t o r i n f o i l s , a d d i n g an energy e q u a t i o n and t u r b u l e n c e model- However, t h e performance and d u r a b i l i t y o f an engine.

i n g , and improved u s e r f r i e n d l i n e s s . The h e a t t r a n s f e r as we c o n t i n u e t o pursue h i g h e r and h i g h e r speeds, from t h e M I N T code a r e shown i n F i g . 14 com- p r e d i c t i o n s advancing t e c h n o l o g y becomes an i n t e r d i s c i p l i n a r y e f f o r t pared t o t h e d a t a f r o m t h e A l l i s o n Gas T u r b i n e r e s e a r c h .

i n v o l v i n g a e r o t h e r m a l l o a d s d e f i n i t i o n and t h e s t r u c - The a n a l y t i c a l l e x p e r i m e n t a l d a t a comparison i s good, t u r a l response o f advanced m a t e r i a l s . T h i s i s espe- however, t h e l o c a t i o n o f boundary l a y e r t r a n s i t i o n was c i a l l y t r u e for h y p e r s o n i c v e h i c l e s where t h e o v e r a l l s p e c i f i e d for t h e a n a l y t i c a l s o l u t i o n .

thermal management and d e s i g n o f t h e v e h i c l e and t h e The U n i v e r s i t y o f Tennessee Space I n s t i t u t e a l s o p r o p u l s i o n system become an i n t e g r a t e d i n t e r a c t i v e developed a t h r e e - d i m e n s i o n a l v i s c o u s f l o w a n a l y s i s e n t i t y . W e now have, or a r e d e v e l o p i n g , tremendous c a p a b i l i t y f o r t h e c u r v e d d u c t experiment u t i l i z i n g t h e a n a l y t i c a l c a p a b i l i t i e s w i t h which one can a t t a c k these P.D. Thomas code (Thomas, 1979) as a base. Some a n a l - v e r y complex t e c h n o l o g y i s s u e s .

y t i c a l r e s u l t s f r o m t h i s code a r e shown i n F i g . 6 where a v e c t o r p l o t o f t h e c r o s s - f l o w v e l o c i t i e s a r e compared LOOK TO THE FUTURE w i t h t h e e x p e r i m e n t . I n a d d i t i o n , a stream sheet i s shown as i t propagates t h r o u g h t h e d u c t and i s t w i s t e d Many r e c e n t s t u d i e s have been made to assess t h e and s t r e t c h e d . A d d i t i o n a l comparisons o f a n a l y s i s and a e r o p r o p u l s i o n t e c h n o l o g y r e q u i r e m e n t s i n t o t h e 2 1 s t experiment show t h a t t h e t h i n t u r b u l e n t boundary l a y e r t o suggest t h a t s i g n i f - The consensus seems c e n t u r y .

r e s u l t s o f t h i s experiment a r e d i f f i c u l t t o c a l c u l a t e i c a n t t e c h n o l o g y advances a r e r e q u i r e d t o meet t h e w i t h c u r r e n t t u r b u l e n c e models.

g o a l s o f t h e f u t u r e . Whether t h e g o a l s a r e h i g h speed s u s t a i n e d f l i g h t , s i n g l e - s t a g e - t o - o r b i t o r subsonic CONCLUDING REMARKS t r a n s p o r t , t h e i s s u e s f o r t h e d e s i g n e r a r e improved f u e l e f f i c i e n c y , h i g h t h r u s t - t o - w e i g h t , improved i s an o v e r v i e w o f t h e T u r b i n e Heat S i n c e t h i s paper component performance whi l e m a i n t a i n i n g component T r a n s f e r a s p e c t s o f t h e HOST program i t has been pre- d u r a b i l i t y and reduced o p e r a t i n g and maintenance sented as a c a t a l o g i n g and summarizing o f t h e v a r i o u s w i l l o n l y serve t o i n c r e a s e t h e c o s t s . These i s s u e s a c t i v i t i e s . More i m p o r t a n t l y , t h e HOST program s h o u l d " o p p o r t u n i t i e s " a v a i l a b l e t o t h e r e s e a r c h e r i n aero- be viewed as a c a t a l y s t b r i n g i n g t o g e t h e r t h e gas t u r - thermal l o a d s and s t r u c t u r e s a n a l y s i s . The v e r i f i a b l e b i n e community and b u i l d i n g a t e c h n o l o g y momentum t o p r e d i c t i o n s o f unsteady f l o w f i e l d s w i t h s i g n i f i c a n t c a r r y advanced p r o p u l s i o n systems i n t o t h e f u t u r e . secondary flow phenomena and coupled t h e r m a l l v e l o c i t y S p e c i f i c a l l y , t h e HOST T u r b i n e Heat T r a n s f e r S u b p r o j e c t p r o f i l e s i s a f e r t i l e r e s e a r c h a r e a . Very l i t t l e p r o - t o t h e f o l l o w i n g accomplishments.

can p o i n t g r e s s has been made t o d a t e i n a p p l y i n g CFD t e c h n i q u e s 1 . The impact o f a x i a l s p a c i n g and i n l e t t u r b u l e n c e t o t h e i n t r i c a t e and complex c o o l a n t channels r e q u i r e d on h e a t t r a n s f e r and aerodynamics t h r o u g h o u t t h e s t a t o r - i n t h e h o t - s e c t i o n components. With t h e expected r o t o r - s t a t o r o f a stage and o n e - h a l f a x i a l t u r b i n e was advances i n h i g h - t e m p e r a t u r e m a t e r i a l s t h e components measured. H i g h - t u r b u l e n c e and p o s t - t r a n s i t i o n a l e f f e c t s w i t h s i g n i f i c a n t aerothermal l o a d s problems w i l l expand on t h e p r e s s u r e s u r f a c e o f b o t h s t a t o r and r o t o r can beyond t h e a i r f o i l s and combustor l i n e r s t o shrouds, cause t h e S t a n t o n number t o be g r e a t e r than t h e f u l l y r i m s , s e a l s , b e a r i n g s , compressor b l a d i n g , d u c t i n g , t u r b u l e n t v a l u e . n o z z l e s , e t c . The i s s u e s to be addressed and t h e tech- 2. Reynolds number, Mach number, c u r v a t u r e , and n o l o g y advances r e q u i r e d t o p r o v i d e t h e a e r o p r o p u l s i o n w a l l - t o - g a s t e m p e r a t u r e effect.s on boundary l a y e r t r a n s - systems o f t h e 2 1 s t c e n t u r y a r e q u i t e c h a l l e n g i n g .

i t i o n and h e a t t r a n s f e r were determined f o r a s t a t o r

a i r f o i 1 . REFERENCES

3. Showerhead and " g i l l - r e g i o n ' ' f i l m - c o o l i n g were shown t o have b o t h b e n e f i c i a l and adverse e f f e c t s on t h e Anderson, 0. L., 1985a. "Assessment o f a 3-D Boundary r e c o v e r y r e g i o n h e a t t r a n s f e r a t s i m u l a t e d e n g i n e c o n d i - Layer A n a l y s i s t o P r e d i c t Heat T r a n s f e r and F l o w F i e l d t i o n s which depended on s p e c i f i c o p e r a t i n g c o n d i t i o n s . i n a T u r b i n e Passage," NASA CR-174894.

4. Heat T r a n s f e r i n b o t h smooth-wall and t u r b u l a t e d - w a l l s e r p e n t i n e r o t a t i n g c o o l a n t passages Anderson, 0. L . , 1985b, " C a l c u l a t i o n o f Three- were c o r r e l a t e d w i t h a r o t a t i o n number f o r t h e low- Dimensional Boundary Layers on R o t a t i n g T u r b i n e p r e s s u r e s u r f a c e . The h i g h - p r e s s u r e s u r f a c e h e a t Blades," Three Dimensional Flow Phenomena i n F l u i d t r a n s f e r was n o t w e l l c o r r e l a t e d . Machinery. A . Hamed. J. H e r r i n g , and L. P o v i n e l l i , 5 . Blade t i p c a v i t y h e a t t r a n s f e r was shown t o be eds.. ASME, New York, pp. 121-132.

s t r o n g l y dependent on t h e c a v i t y aspect r a t i o and a n g l e - o f - a t t a c k to b l a d e t i p f l o w d i r e c t i o n .

Anderson, 0. L . , and C a p l i n , 6.. 1985c, " U s e r ' s Manual 6. Heat t r a n s f e r measurements i n h i g h - t u r b u l e n c e f o r Three Dimensional Boundary Layer (BL3-D) Code," i n t e n s i t y f l o w f i e l d s , s i m u l a t i n g combustor e x i t NASA CR-174899.

phenomena, shows augmentation r a t e s o f 3X t o 5X depend- i n g on t h e l e n g t h s c a l e o f t h e t u r b u l e n c e .

B l a i r , M. F . , D r i n g . R . P . , and J o s l y n , H . D., 1988a, 7 . Improved d e f i n i t i o n o f t h e i n i t i a l c o n d i t i o n s "The E f f e c t s o f Turbulence and S t a t o r / R o t o r I n t e r a c t i o n s and boundary c o n d i t i o n s which a r e a p p l i c a b l e t o t u r b i n e

on T u r b i n e Heat T r a n s f e r , P a r t I 1 - E f f e c t s o f Reynolds

a i r f o i l s was s u c c e s s f u l i n i m p r o v i n g t h e p r e d i c t i o n o f Number and I n c i d e n c e , " ASME Paper t o be p r e s e n t e d a t t h e a i r f o i l h e a t t r a n s f e r for a wide range o f g e o m e t r i e s 3 3 r d ASME Gas T u r b i n e Conference, The N e t h e r l a n d s .

u s i n g t h e STAN5 boundary l a y e r code.

8 . The Lam-Bremhorst low-Reynolds number k-e t u r - B l a i r , M. F . , D r i n g , R . P., and J o s l y n , H. D., 1988b, bulence model was m o d i f i e d t o a l s o improve t h e p r e d i c - "The E f f e c t s o f Turbulence and S t a t o r / R o t o r I n t e r a c t i o n s t i o n s o f a i r f o i l h e a t t r a n s f e r under t r a n s i t i o n a l f l o w s

on T u r b i n e Heat T r a n s f e r , P a r t I - Design O p e r a t i n g

w i t h b o t h f r e e - s t r e a m t u r b u l e n c e and p r e s s u r e g r a d i e n t s .

C o n d i t i o n s , " ASME Paper t o be p r e s e n t e d a t t h e 3 3 r d ASME Gas T u r b i n e Conference, The N e t h e r l a n d s .

Chyu, M. K . , Metzger. D . E . , and Hwan, C . L . , 1987.

F l o r s c h u e t z , L. W . , and Su, C. C . , 1987, "Recovery "Heat T r a n s f e r i n Shrouded R e c t a n g u l a r C a v i t i e s , " E f f e c t s on Heat T r a n s f e r C h a r a c t e r i s t i c s W i t h i n an J o u r n a l o f Thermophysics and Heat T r a n s f e r , V o l . 1 .

A r r a y o f I m p i n g i n g J e t s , " Heat T r a n s f e r and F l u i d Flow NO. 2, pp. 247-252.

i n R o t a t i n g Machinery, W.J. Yang, ed., Hemisphere P u b l i s h i n g Corp., Washington, D . C . , pp. 375-387.

Crawford, M . E . , and Kay, W . M . , 1976, "STAN5 - A

Program f o r Numerical Computation o f Two-Dimensional Gladden, H . J., Yeh, F . C . , and Fronek, D. L., 1985a, I n t e r n a l and E x t e r n a l Boundary Layer Flows," NASA "Heat T r a n s f e r R e s u l t s and O p e r a t i o n a l C h a r a c t e r i s t i c s CR-2742.

o f t h e NASA Lewis Research Center Hot S e c t i o n Cascade T e s t F a c i l i t y , " ASME Paper 85-GT-82. (NASA TM-86890).

Crawford, R . A . , e t a l , 1985, "Mean V e l o c i t y and Turbulence Measurements i n a 900 Curved Duct With T h i n Gladden, H . J . , and P r o c t o r , M. P . , 1985b, " T r a n s i e n t , I n l e t Boundary Layer," NASA CR-174811.

Technique f o r Measuring Heat T r a n s f e r C o e f f i c i e n t s on S t a t o r A i r f o i l s i n a J e t Engine Environment," A I A A I D r i n g , R. P . . B l a i r , M . F . , and J o s l y n . H . D . , 1986a.

Paper 85-1471. (NASA TM-87005).

"The E f f e c t s o f I n l e t Turbulence and R o t o r S t a t o r I n t e r a c t i o n s on t h e Aerodynamics and Heat T r a n s f e r o f a Gladden, H . J . , Yeh, F . C . , and A u s t i n , P . J . J r . , 1987, Large-Scale R o t a t i n g T u r b i n e Model. V o l . 111, Heat "Computation o f Full-Coverage, Film-Cooled A i r f o i l T r a n s f e r Data T a b u l a t i o n . 65% A x i a l Spacing." NASA Temperatures by Two Methods and Comparison W i t h H i g h CR-179468.

Heat F l u x Data," ASME Paper 87-GT-213. (NASA TM-88931).

D r i n g , R. P . . B l a i r , M. F., and J o s l y n , H . D., 1986b.

H i p p e n s t e e l e , S. A . , R u s s e l l , L. M . , and T o r r e s , F . J . , "The E f f e c t s o f I n l e t Turbulence and R o t o r / S t a t o r 1985, " L o c a l H e a t - T r a n s f e r Measurements on a Large I n t e r a c t i o n s on t h e Aerodynamics and Heat T r a n s f e r o f a Scale-Model T u r b i n e Blade A i r f o i l U s i n g a Composite o f Large-Scale R o t a t i n g T u r b i n e Model. Vol. I V , Aerodynamic a Heat Element and L i q u i d C r y s t a l s , " ASME Paper NASA CR-179469.

Data T a b u l a t i o n , " 85-GT-59. (NASA TM-86900).

D r i n g , R. P., B l a i r , M. F . . and J o s l y n , H . D . , 1986c, H y l t o n . L . D., e t a l , 1983, " A n a l y t i c a l and Experimental "The E f f e c t s o f I n l e t Turbulence and R o t o r S t a t o r E v a l u a t i o n o f t h e Heat T r a n s f e r D i s t r i b u t i o n Over t h e o f a I n t e r a c t i o n s on t h e Aerodynamics and Heat T r a n s f e r Surfaces o f T u r b i n e Vanes," NASA CR-168015.

I Large-Scale R o t a t i n g T u r b i n e Model. V o l . 11, Heat Kopper. F . C . , 1984, " C o o l a n t Passage Heat T r a n s f e r W i t h I T r a n s f e r Data T a b u l a t i o n . 15% A x i a l Spacing," NASA CR-179467. R o t a t i o n , " T u r b i n e Engine Hot S e c t i o n Technology, NASA CP-2339, pp. 401 -409.

D r i n g . R. P . . e t a l . 1987, "The E f f e c t s o f I n l e t Turbulence and R o t o r / S t a t o r I n t e r a c t i o n s on t h e Lord, W. K . . P i c k e t t , G . F . , Sturgess, G . J . , and Aerodynamics and Heat T r a n s f e r of a Large-Scale Weingold, H. D., 1987, " A p p l i c a t i o n o f CFD Codes t o t h e R o t a t i n g T u r b i n e Model, Vol. I," NASA CR-4079. Design and Development o f P r o p u l s i o n Systems," Supercomputing i n Aerospace, NASA CP-2454, P . K u t l e r F l o r s c h u e t z , L . W . , and I s o d a , Y . , 1982a, "Flow and H.Yee, eds., NASA, Washington, D . C . . pp. 139-148.

D i s t r i b u t i o n s and D i s c h a r g e C o e f f i c i e n t E f f e c t s f o r J e t A r r a y Impingement W i t h I n i t i a l C r o s s f l o w , " ASME Paper Nealy, D. A . . e t a l , 1983, "Measurement o f Heat T r a n s f e r 82-GT-156. D i s t r i b u t i o n Over t h e S u r f a c e s o f H i g h l y Loaded T u r b i n e Nozzle Guide Vanes," ASME Paper 83-GT-53,.

F l o r s c h u e t z . L. W . , e t a l , 1982b. " J e t A r r a y Impingement Flow D i s t r i b u t i o n s and Heat T r a n s f e r C h a r a c t e r i s t i c s - Nealy, D. A . , M i h e l c , M . S . , H y l t o n , L. D . , and E f f e c t s o f I n i t i a l C r o s s f l o w and Nonuniform A r r a y Gladden, H. J . , 1984, "Measurements o f Heat T r a n s f e r Geometry - Gas T u r b i n e Engine Component C o o l i n g , " NASA D i s t r i b u t i o n Over t h e Surfaces o f H i g h l y Loaded T u r b i n e CR-3630. Nozzle Guide Vanes," J o u r n a l o f E n g i n e e r i n g f o r Gas T u r b i n e s and Power, V o l . 106, No. 1, pp. 149-158.

I F l o r s c h u e t z , L. W . , Metzger, D. E . , and Su, C. C..

1983, "Heat T r a n s f e r C h a r a c t e r i s t i c s f o r J e t A r r a y R i c h a r d s , D. R . , and F l o r s c h u e t z , L. W . , 1984, "Forced Impingement w i t h I n i t i a l C r o s s f l o w , " ASME Paper C o n v e c t i o n Heat T r a n s f e r t o A i r / W a t e r Vapor M i x t u r e s , " 83-GT-28. NASA CR-3769.

F l o r s c h u e t z , L. W . , and Tseng, H. H . . 1984a, " E f f e c t o f Schmidt, R . C . , and Patankar, S. V . , 1987, " P r e d i c t i o n Nonuniform Geometries on Flow D i s t r i b u t i o n s and Heat o f T r a n s i t i o n on a F l a t P l a t e Under t h e I n f l u e n c e o f T r a n s f e r C h a r a c t e r i s t i c s for A r r a y s o f I m p i n g i n g J e t s , " Free-Stream Turbulence U s i n g Low-Reynolds-Number Two- ASME Paper 84-GT-156. E q u a t i o n Turbulence Models," ASME Paper 87-HT-32.

F l o r s c h u e t z , L. W . , and Metzger, D . E . , 1984b. " E f f e c t Stepka, F . S . , 1980, " A n a l y s i s of U n c e r t a i n t i e s i n

i

o f I n i t i a l C r o s s f l o w Temperature on T u r b i n e C o o l i n g T u r b i n e M e t a l Temperature P r e d i c t i o n s , " NASA TP-1593.

Wlth J e t A r r a y s , " Heat and Mass T r a n s f e r i n R o t a t i n g Machinery, D.E. Metzger and N. Afgan, eds., Hemisphere S t u r g e s s , G . J., and D a t t a , P . , 1987, " C a l c u l a t i o n o f P u b l i s h i n g Corp., Washingotn. D.C., pp. 499-510. Flow Development i n R o t a t i n g Passages for Cooled Gas T u r b i n e Blades," Computers i n E n g i n e e r i n g - 1987, F l o r s c h u e t z , L . W . , and Su, C. C., 1985, "Heat T r a n s f e r V o l . 3. ASME. New York, pp..149-158.

C h a r a c t e r i s t i c s W i t h i n an A r r a y o f I m p i n g i n g J e t s , " NASA CR-3936. Thomas, P . D . , 1979, "Numerical Method f o r P r e d i c t i n g Flow C h a r a c t e r i s t i c s and Performance o f Nonaxisymmetric Nozzles Theory," NASA CR-3147.

Turner, E . R . , e t a l , 1985, " T u r b i n e Vane E x t e r n a l Heat Weinberg, B. C . , e t . a l , 1985 " C a l c u l a t i o n s o f Two- T r a n s f e r , V o l . I - A n a l y t i c a l and Experimental and Three-Dimensional T r a n s o n i c Cascade Flow F i e l d s E v a l u a t i o n o f S u r f a c e Heat Transfer D i s t r i b u t i o n s W i t h U s i n g t h e Navier-Stokes E q u a t i o n s , " ASME Paper 85-GT-66.

Leading Edge Showerhead F i l m C o o l i n g , " NASA CR-174827.

Yang, R. J . , e t a l , 1985, " T u r b i n e Vane E x t e r n a l Heat Vatsa, V . N . , 1985, " A Three-Dimensional Boundary Layer T r a n s f e r , Vol. I 1 - Numerical S o l u t i o n s o f t h e N a v i e r - A n a l y s i s I n c l u d i n g H e a t - T r a n s f e r and B l a d e - R o t a t i o n Stokes Equations f o r Two- and Three-Dimensional T u r b i n e E f f e c t s , " 3 r d Symposium on Numerical and P h y s i c a l Cascades With Heat T r a n s f e r , " NASA CR-174828.

Aspects o f Aerodynamic Flows, T . Cebeci, ed., C a l i f o r n i a S t a t e U n i v e r s i t y , p p . 10-45 t o 10-59,

TABLE I . - TURBINE HEAT TRANSFER SUBPROJECT S U M M A R Y

Results Figures Work element 1 and 2 Provide fundamental experimental

data bases w i t h focus on -

A i r f o i l w i t h f i l m coolinga F i l m cooling Curved duct Secondary flows Impingement cooling Impingement p a t t e r n correlations Combustor e x i t simulation Large-scale, high-intensity turbulence Real engine environment The r e a l environment Rotating experiments Large low-speed turbinea Rotor-stator i n t e r a c t i o n Rotating coolant passage C o r i o l i s and buoyancy e f f e c t s Tip reglon simulator Flow across moving a i r f o i l t i p Warm core turbine Vane and blade passage flow map f u l l y scaled Analyses Enhance a n a l y t i c tools f o r turblne a p p l i c a t i o n Adapt boundary layer code t o STAN5 modi f i cationsa current a i r f o i l data Three-dimenslonal Zoom focus on Three-dimensional regions boundary layer Unsteady boundary 1 ayera Account f o r r o t o r - s t a t o r i n t e r a c t l o n e f f e c t s Teach code w i t h r o t a t l o n a Three-dimensional Navier-Stokes v i t h r o t a t i o n terms Low Reynolds number Develop turbine a i r f o i l s p e c i f i c turbulence model Mint codeb Three-dimensional Navier-Stokes applied t o turbine a i r f o i l geometry aExperiment and analysis I n the same contract.

done under two separate contracts.

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HIGHLY TURBULENT REAL ENGINE FLOW SIMULATION CD-85-16934 4 C D - 8 5 - 1 6 9 6 4 FIGURE 1. - TYPICAL COOLED AIRCRAFT GAS FIGURE 2. - COMPLEX FLOW PHENOMENA I N A TURBINE PASSAGE, TURBINE BLADE. SEE TABLE I FOR DESCRIP- TION OF NUMBERED FLOW PHENOMENA. SEE TABLE I FOR DESCRIPTION OF NUMBERED FLOW PHENOMENA.

RIGS O R ENGINES HIGH SPEED WARM UNSTEADY TURBINE LARGE LOW STATIC CASCADES COLD

’ SPECIFIC I ANNULAR AND WARN ANNULAR I \

WIND TUNNELS AND FUNDAMENTAL I ANALYTIC

PHENORENA I MODELS TRANSITION. VISUALIZATION. MODELING

I TURBULENCE, F I L M COOLING I

///////////////////////

FIGURE 3.- BUILDING BLOCK APPROACH TO TURBINE AEROTHERRAL RESEARCH.

CD-85-16940 I TY ( A ) BY LOCATION OF RESEARCH.

EXPER 1 .YTICAL ( B ) BY TYPE OF RESEARCH.

FIGURE 4.- HOST TURBINE HEAT TRANSFER SUBPROJECT DISTRIBUTION OF RESOURCES.

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NOMINAL RUN E X I T REYNOLDS CONDITIONS NUMBER M2 = 0.90 + 1 . 5 1 ~ 1 0 ~ T,,/TG = 0.81 0 1 . 9 6 ~ 1 0 ~ Tu = 6.5% o 2 . 4 9 ~ 1 0 ~ L H , = 1135 W/n2/c + c 4 0 W 1.0 .8 .6 .4 .2 0 .2 .4 .6 .8 1.0 I SURFACE DISTANCE, S/ARC ( B ) NONFILM-COOLED A I R F O I L HEAT TRANS- ( A ) THREE-VANE CASCADE.

FER COEFFICIENTS.

D4TA M 2 RE2 Pc,os/PT 'C,LE/PT T ~ T G BASE .75 2.00E6 0 .75 2.05E6 1.10 1.10 .67 A .74 2.00E6 1.10 1.05 .65 pC/pT o .75 2.01E6 1.10 1.02 .65 3 .75 2.00E6 1.10 1.00 .66 4 1.10

+ 1.05 A . a

-4 :: -1 SUCTION 1.0 .8 .6 .4 .2 0 .2 .4 .6 .8 1.0 100 80 60 40 20 40 60 80 100 SURFACE DISTANCE, S/ARC SURFACE DISTANCE. S/ARC ( C ) INFLUENCE OF LEADING EDGE FILM-COOLING ON HEAT (0) COPlBlNEO LEADING EDGE AN0 DOWN- TRANSFER. S T R E W FILM-COOLING.

FIGURE 5. - GAS-SIDE EXPERIMENTAL HEAT TRANSFER DATA FOR BOTH NON-FILM-COOLED AND F I L M COOLED A I R F O I L S . A L L I S O N GAS TURBINE D I V I S I O N .

CURVED-DUCT FACILITY 138 h:. A T - a".

3-D LV OPTICAL SYSTEM STREAM SHEET VELOCITY PATTERN THROUGH DUCT ANALYTICAL RESULTS LOU REYNOLDS NUHBER DATA EXPERlMENTAL RESULTS

FIGURE 6. - THREE-DIMENSIONAL FLOW-FIELD RASUREMENTS I N A CURVED DUCT REPRESENTING AN

AIRFOIL PASSAGE.

UNIVERSITY OF TENNESSEE SPACE INSTITUTE.

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UALL TEWERATURE RESPONSE TO GAS TEMPERATURE RAMP EXPERIPENTAL TEMPERATURE PEASUREPENT LOCAL HEAT TRANSFER COEFFICIENTS DETERMINE F R M DYNMIC SIGNAL ANALYSIS ’.

Y 5 1574 ylc o DYNMIC SIGNAL ANALYSIS DATA

s : =

STEADY STATE HEAT I X’. 6\62

: I FLUX GAGE DATA

%

c - STAN5 PREDICTION 1 f . 15.3% UNCERTAINTY 0 10 20 30 40 50 loo0 0 . 2 .4 . 6 .8 1.0 FRACTIONAL DISTANCE FROM CD-85-17458 LEADING EDGE FIGURE 7. - HEAT FLUX PEASUREENTS M D E I N A SIMULATED REAL ENGINE ENVIRONPENT ON STATOR AIRFOILS.

LEWIS RESEARCH CENTER.

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OF POOR QUALITY

THE FREE JET X U . U ' , h , ETC.

BLOWER _------

HEAT TRANSFER SURFACE U . WS TU SCALE. CH

6r

G I , 0.87 48 9

< 0.89 63 10 - 3

2 k s 0.82 0.92 37 47 98

m 4 - 2 9 2 . 8 1 0 - 1 7 A Tu = 50% A A AA& 10-2 LAM I NAR 103 104 lo5 106 REX FIGURE 8. - HEAT TRANSFER AUGMENTATION RESULTING FROM HIGH FREE STREAM TURBULENCE AND SCALE.

STANFORD UNIVESITY.

r FIRS1 ROTOR 0 L M I TURB 0 HIGH TURB ,006 PRESSURE ,002 0 - -2 - 1 0 - 2 - 1 0 1 9 LARGE SCALE ROTARING R I G 1-1/2 STAGE TURBINE COIFIGURATIOW F I R S T VANE AND ROTOR CASf REIWOMD FIGURE 9. - ROTOR/STATOR INTERACTION AND THE AFFECT W HEAT TRANSFER OF H I G H AND LOU FREESTREPA TURBULENCE.

U N I T E D TECHNCiOGlfS RESEARCH CENTER.

\

- '-MOVING SURFACE

U" .012 U P S T R E M CAVITY FLOOR I W W N S T R E M

!I TOP SURFACE

TOP SURFACE j

e.

g y1.0 -.5 0 .5 1.0 1.5 2.0

z ,012 .om .OO4 0 2 4 X/D FIGURE 10. - EXPERIMENTAL HEAT TRANSFER RESULTS FOR ARIZONA STATE A SIMULATED B L A M T I P CAVITY.

UNIVERSITY.

RE = 25 000 SYMBOL A T , FLAGS OF

b It0

0- 80

9 120

0 160 OPEN SYMBOLS - SMOOTH WALL SOLID SYMBOLS - ROUGH WALL LOW PRESSURE H I G H PRESSURE

f

5r SURFACE SURFACE

-0 L r NONROTATIONAL W

I I I I I

I I I I

FIGURE 11. - THE EFFECTS OF ROTATION ON HEAT TRANSFER I N MULTIPASS COOLANT PASSAGES WITH AND WITHOUT TURBULATORS ARE SHOWN PRATT AND WHITNEY AIRCRAFT.

FOR AN OUTWARD FLOWING PASSAGE.

PREDICTION DATA RE2 X * 2.49 - - - - - - - t 1-96 0 1.51 * 1.0 c L w 2 . 8 LL

-

+ .2 PRESSURE SUCTION W 4 I

I I I I I I

PREDICTION FTU FTG DATA P,/P, 0 1.10 .4 .2 -.2 -.4 100 80 60 40 20 0 20 40 60 80 100 SURFACE DISTANCE. S/ARC FIGURE 12. - A MODIFIED STAN-5 BOUNDARY LAYER ANALYSIS I S C W A R E D WITH KASUREMNTS FROn A NON-FILN-COOLED AIRFOIL AND THE S M E AIRFOIL GEOPYTRY WITH A SHOWER- HEAD DESIGN. ALLISON GAS TURBINE D I V I S I O N .

TURBULENCE = 6.5 PERCENT: E X I T RACH NUMBER = 0.90 PRESSURE SIDE

-

1.0 GRADIENT CORRECTION I \ I

-

,2 .8 L

w

-

.6

-

E .4 U co L

s

+ ‘ 2

- 0 1.51~10

+ 4 2 . 4 9 ~ 1 0 ~ W I TYPICAL 0-GRID MESH PRESSURE SIDE SUCTION SIDE \ I 1 . O r I y 1.0 . 8 .6 .4 . 2 0 .2 .4 .6 .8 1.0 SURFACE DISTANCE, S/ARC FIGURE 14. - A FULLY E L L I P T I C NAVIER-STOKES SOLUTION I S COMPARED WITH THE SAME EXPERIENTAL MEASUREMENTS FOUND I N FIGURES 12 AND 13. SCIENTIFIC RESEARCH ASSOCIATE. INC.

STRUCTURAL ANALYSIS METHODS DEVELOPMENT FOR TURBINE H O T SECTION COMPONENTS R. L. Thompson National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio three-dimensional n o n l i n e a r structural m e t h o d s and A B S T R A C T and e x p e r i m e n t a t i o n t o c a l i b r a t e and code d e v e l o p m e n t , v a l i d a t e t h e m o d e l s and codes. T h e s e t e c h n o l o g y a r e a s T h i s p a p e r s u m m a r i z e s t h e structural a n a l y s i s were s e l e c t e d not o n l y b e c a u s e t o d a y s hot s e c t i o n com- t e c h n o l o g i e s and a c t i v i t i e s o f t h e N A S A Lewis R e s e a r c h ponent d e s i g n s a r e m a t e r i a l l y a n d s t r u c t u r a l l y diffi- C e n t e r ' s gas t u r b i n e e n g i n e H o t S e c t i o n T e c h n o l o g y cult t o a n a l y z e w i t h e x i s t i n g analytical t o o l s , but ( H O S T ) program. T h e t e c h n o l o g i e s s y n e r g i s t i c a l l y b e c a u s e e v e n g r e a t e r d e m a n d s will be p l a c e d o n t h e d e v e l o p e d a n d v a l i d a t e d include: time-varying t h e r m a l / a n a l y s i s of a d v a n c e d designs. I t is t h e need f o r mechanical load m o d e l s ; c o m p o n e n t - s p e c i f i c a u t o m a t e d improved e n g i n e p e r f o r m a n c e ( h i g h e r t e m p e r a t u r e s , g e o m e t r i c m o d e l i n g and s o l u t i o n s t r a t e g y c a p a b i l i t i e s ; lower c o o l i n g flows). lower e n g i n e w e i g h t , a n d a d v a n c e d i n e l a s t i c a n a l y s i s m e t h o d s ; i n e l a s t i c consti- improved e n g i n e r e l i a b i l i t y and d u r a b i l i t y w h i c h will t u t i v e m o d e l s ; high-temperature e x p e r i m e n t a l t e c h n i q u e s r e q u i r e a d v a n c e d analytical t o o l s and e x p a n d e d e x p e r i - and e x p e r i m e n t s ; a n d n o n l i n e a r structural a n a l y s i s mental c a p a b i l i t i e s .

codes. F e a t u r e s of t h e p r o g r a m t h a t i n c o r p o r a t e t h e B e c a u s e m a t e r i a l s used in t o d a y ' s t u r b i n e e n g i n e n e w t e c h n o l o g i e s a n d t h e i r a p p l i c a t i o n t o hot s e c t i o n hot s e c t i o n c o m p o n e n t s a r e o p e r a t i n g a t e l e v a t e d c o m p o n e n t a n a l y s i s a n d d e s i g n a r e described. I m p r o v e d t e m p e r a t u r e , time-independent ( p l a s t i c ) and time- and, in s o m e c a s e s , first-time three-dimensional non- d e p e n d e n t ( c r e e p and s t r e s s r e l a x a t i o n ) material linear structural a n a l y s e s of hot s e c t i o n c o m p o n e n t s behavioral p h e n o m e n a o c c u r s i m u l t a n e o u s l y , and t h e s e o f i s o t r o p i c and a n i s o t r o p i c nickel-base s u p e r a l l o y s p h e n o m e n a will be e x a c e r b a t e d in f u t u r e c o m p o n e n t a r e presented.

designs. Classical elastic-plastic t h e o r i e s , w h e r e c r e e p and p l a s t i c i t y a r e u n c o u p l e d d o n o t a d e q u a t e l y c h a r a c t e r i z e t h e s e i n t e r a c t i v e p h e n o m e n a . T h e s e I N T R O D U C T I O N i n t e r a c t i o n s a r e c a p t u r e d w i t h i n e l a s t i c ( v i s c o p l a s t i c o r u n i f i e d ) c o n s t i t u t i v e models. U n d e r H O S T , several Hot s e c t i o n c o m p o n e n t s of a i r c r a f t g a s t u r b i n e high-temperature v i s c o p l a s t i c m o d e l s w e r e d e v e l o p e d f o r e n g i n e s a r e s u b j e c t e d t o s e v e r e thermal-structural s u p e r a l l o y s used i s o t r o p i c and a n i s o t r o p i c nickel-base loading c o n d i t i o n s d u r i n g t h e e n g i n e m i s s i o n cycle.

in hot s e c t i o n c o m p o n e n t s . T h e s e m o d e l s w e r e incorpo- T h e m o s t s e v e r e and d a m a g i n g s t r e s s e s and s t r a i n s a r e rated in several n o n l i n e a r three-dimensional struc- t h o s e induced by t h e s t e e p thermal g r a d i e n t s w h i c h tural a n a l y s i s codes.

o c c u r d u r i n g t h e s t a r t u p and s h u t d o w n t r a n s i e n t s .

T h e a n a l y s i s d e m a n d s placed o n hot s e c t i o n compo- The t r a n s i e n t , a s well a s s t e a d y s t a t e , s t r e s s e s and o f a d v a n c e d nent d e s i g n s r e s u l t not o n l y f r o m t h e use s t r a i n s a r e difficult t o p r e d i c t , in p a r t , b e c a u s e t h e m a t e r i a l s and t h e i r c h a r a c t e r i z a t i o n , but a l s o f r o m t e m p e r a t u r e g r a d i e n t s a n d d i s t r i b u t i o n s a r e not well t h e u s e of n e w a n d i n n o v a t i v e structural d e s i g n con- k n o w n o r r e a d i l y p r e d i c t a b l e a n d , in part, b e c a u s e cepts. T h e r e is a n o b v i o u s need t o d e v e l o p a d v a n c e d the c y c l i c e l a s t i c - v i s c o p l a s t i c b e h a v i o r of t h e mate- computational m e t h o d s and c o d e s , w i t h t h e f o c u s o n r i a l s a t t h e s e e x t r e m e s o f t e m p e r a t u r e and s t r a i n a r e improved a c c u r a c y a n d e f f i c i e r c y , t o p r e d i c t nonlin- not well k n o w n o r r e a d i l y p r e d i c t a b l e .

ear structural r e s p o n s e of a d v a n c e d c o m p o n e n t d e s i g n s .

A broad s p e c t r u m of s t r u c t u r e s r e l a t e d t e c h n o l o g y U n d e r HOST, improved time-varying thermal-mechanl cal p r o g r a m s h a s been u n d e r w a y a t t h e NASA L e w i s t o a d d r e s s load m o d e l s f o r t h e e n t i r e e n g i n e m i s s i o n c y c l e from t h e s e d e f i c i e n c i e s a t t h e basic a s well a s t h e a p p l i e d s t a r t u p t o s h u t d o w n w e r e d e v e l o p e d . T h e thermal model l e v e l s , w i t h p a r t i c i p a t i o n by i n d u s t r y and universities.

r e f i n e m e n t s a r e c o n s i s t e n t w i t h t h o s e r e q u i r e d b y t h e O n e of t h e s e p r o g r a m s w a s t h e s t r u c t u r e s e l e m e n t of t h e structural c o d e s , i n c l u d i n g c o n s i d e r a t i o n s o f mesh- t u r b i n e e n g i n e H o t S e c t i o n l e c h n o l o g y ( H O S T ) program.

p o i n t d e n s i t y , s t r a i n c o n c e n t r a t i o n s , and thermal gra- The s t r u c t u r e s e l e m e n t f o c u s e d o n t h r e e k e y t e c h n o l o g y d i e n t s . A n a u t o m a t e d component-specific g e o m e t r i c areas: i n e l a s t i c c o n s t i t u t i v e model d e v e l o p m e n t ,

PREC€DING PAGE BLANK NOT FILMED

A second example i s t h e a n a l y s i s of an a i r f o i l lnodeling c a p a b i l i t y which w i l l produce t h r e e - d i m e n s i o n a l o f a t y p i c a l cooled t u r b i n e b l a d e . S i m u l a t i o n s were f i n i t e element models o f t h e h o t s e c t i o n components r u n i n which a c l a s s i c a l c r e e p - p l a s t i c i t y model was was a l s o developed. S e l f - a d a p t i v e s o l u t i o n s t r a t e g i e s compared w i t h t h e Walker and Bodner-Partom models for Here developed and i n c l u d e d t o f a c i l i t a t e t h e s e l e c - B1900+Hf m a t e r i a l . The a i r f o i l was e x e r c i s e d t h r o u g h t i o n o f a p p r o p r i a t e elements, mesh s i z e s , e t c . New t h r e e f u l l f l i g h t s p e c t r a o f t a x i , t a k e o f f , c l i m b , and improved n o n l i n e a r t h r e e - d i m e n s i o n a l s t r u c t u r a l c r u i s e , descent, t a x i , and shutdown. Computational a n a l y s i s codes, i n c l u d i n g temporal elements w i t h time- e f f i c i e n c y w i t h t h e u n i f i e d models was as good o r dependent p r o p e r t i e s t o account f o r creep e f f e c t s i n b e t t e r t h a n w i t h a more c l a s s i c a l e l a s t i c p l a s t i c the m a t e r i a l s and components, were developed. A d a t a approach. The e f f e c t i v e s t r e s s versus s t r a i n response t r a n s f e r module was developed t o a u t o m a t i c a l l y t r a n s - a t t h e a i r f o i l c r i t i c a l l o c a t i o n i s compared i n F i g . 4 f e r temperatures from f i n i t e d i f f e r e n c e and f i n i t e for a l l t h r e e c o n s t i t u t i v e models. The u n i f i e d models element thermal a n a l y s i s codes t o f i n i t e element y i e l d v e r y s i m i l a r r e s u l t s b u t s u b s t a n t i a l l y d i f f e r e n t s t r u c t u r a l a n a l y s i s codes.

f r o m t h e c l a s s i c a l c r e e p - p l a s t i c i t y model. U n f o r t u - E s s e n t i a l f o r t h e c o n f i d e n t use o f these models n a t e l y , n o e x p e r i m e n t a l r e s u l t s a r e a v a i l a b l e or e a s i l y and s t r u c t u r a l a n a l y s i s codes i n t h e a n a l y s i s and o b t a i n a b l e f o r t h i s complex problem.

d e s i g n of h o t s e c t i o n components i s t h e i r c a l i b r a t i o n I n summary, t h e program has demonstrated t h a t f o r and v a l i d a t i o n . Under HOST, e x p e r i m e n t a l f a c i l i t i e s t h e c a s t n i c k e l - b a s e a l l o y s s t u d i e d , B1900+Hf and w e r e upgraded and experiments conducted t o c a l i b r a t e MAR-M247, b o t h i s o t h e r m a l and n o n i s o t h e r m a l complex and v a l i d a t e t h e models and codes developed. Unique l o a d i n g h i s t o r i e s can be w e l l p r e d i c t e d u s i n g t h e u n i - u n i a x i a l and m u l t i a x i a l h i g h - t e m p e r a t u r e thermomechan- f i e d c o n s t i t u t i v e model i c a l t e s t s were conducted. I n a d d i t i o n , u n i q u e t h e r - approach w i t h a l l necessary m a t e r i a l c o n s t a n t s d e r i v e d s o l e l y from i s o t h e r m a l t e s t momechanical t e s t s on s e c t i o n s o f c o n v e n t i o n a l and d a t a .

advanced combustor l i n e r s were conducted i n t h e S t r u c - The program has a l s o demonstrated r a t h e r conclu- t u r a l Component Response r i g a t NASA Lewis. Exten- s i v e l y t h a t t h e u n i f i e d c o n s t i t u t i v e model concept i s s i v e , q u a l i t y databases w e r e generated. Advanced s t r a i n a v e r y powerful tool for p r e d i c t i n g m a t e r i a l response and temperature i n s t r u m e n t a t i o n was a l s o e v a l u a t e d .

i n h o t s e c t i o n comcments under complex, t i m e - v a r y i n g , Table I i s a summary o f t h e c o n t r a c t s and g r a n t s thermomechanical l o a d i n g s . This c o n f i d e n c e i s g a i n e d t h a t were an i n t e g r a l p a r t of t h e s t r u c t u r e s element from e x t e n s i v e c o r r e l a t i o n s between two e x i s t i n g under HOST. The r e s e a r c h e f f o r t s o f t h e g r a n t s and models and a l a r g e base o f e x p e r i m e n t a l d a t a c o v e r i n g c o n t r a c t s , as w e l l as in-house e f f o r t s , a r e d e s c r i b e d t h e range i n s t r e s s , s t r a i n r a t e , and temperature o f i n t h e Daper a l o n g w i t h t h e most s i g n i f i c a n t o f t h e i n t e r e s t . The u n i f i e d c o n s t i t u t i v e models have a l s o many accomplishments for each. F i g u r e 1 summarizes been demonstrated t o be c o m p u t a t i o n a l l y e f f i c i e n t when t h e n o n l i n e a r s t r u c t u r a l a n a l y s i s t e c h n o l o g i e s and i n c o r p o r a t e d i n t o a l a r g e f i n i t e element computer code a c t i v i t i e s under HOST.

(MARC).

I S O T R O P I C NATERIAL MODELING General E l e c t r i c C o n t r a c t Southwest Research I n s t i t u t e C o n t r a c t U n i f i e d c o n s t i t u t i v e models were a l s o developed U n i f i e d c o n s t i t u t i v e models were developed for and v a l i d a t e d for s t r u c t u r a l a n a l y s i s o f t u r b i n e s t r u c t u r a l a n a l y s i s of t u r b i n e engine h o t s e c t i o n com- e n g i n e h o t s e c t i o n components under NASA/HOST c o n t r a c t ponents under NASAIHOST c o n t r a c t NAS3-23925, " C o n s t i - NAS3-23927, " C o n s t i t u t i v e M o d e l l n g for I s o t r o p i c Mate- t u t i v e Modeling f o r I s o t r o p i c M a t e r i a l s " (Chan e t a l . , r i a l s , " (Ramaswamy, 1986). A s p a r t o f t h i s e f f o r t , 1986). D u r i n g t h i s p r o j e c t , two e x i s t i n g models o f s e v e r a l v i s c o p l a s t i c c o n s t i t u t i v e t h e o r i e s were e v a l u - t h e u n i f i e d t y p e were developed f o r a p p l i c a t i o n t o a t e d a g a i n s t a l a r g e u n i a x i a l and m u l t i a x i a l d a t a base i s o t r o p i c , c a s t , n i c k e l - b a s e a l l o y s used f o r a i r - on Ren6 80 m a t e r i a l , which i s a c a s t n i c k e l - b a s e a l l o y c o o l e d t u r b i n e blades and vanes. The two models a r e used i n t u r b i n e b l a d e and vane a p p l i c a t i o n s . I n i t i a l l y , those o f Walker (1981). and o f Bodner and Partom i t was t h e i n t e n t to e v a l u a t e o n l y a v a i l a b l e t h e o r i e s ; (1975). Both models were demonstrated t o y i e l d good however, i t was f o u n d t h a t no a v a i l a b l e approach was c o r r e l a t i o n w i r h e x p e r i m e n t a l r e s u l t s f o r two a l l o y s : s a t i s f a c t o r y i n modeling t h e h i g h temperature t i m e PWA a l l o y B1900+Hf and MAR-M247. The e x p e r i m e n t a l dependent b e h a v i o r o f Ren6 80. A d d i t i o n a l c o n s i d e r a - c o r r e l a t i o n s were made w i t h t e s t i n g under u n i a x i a l and t i o n s i n model development i n c l u d e d t h e c y c l i c s o f t e n - b i a x i a l t e n s i l e , creep, r e l a x a t i o n , c y c l i c , and t h e r - i n g b e h a v i o r o f Ren6 80, r a t e independence a t lower momechanical l o a d i n g c o n d i t i o n s o v e r a range i n s t r a i n temperatures, and t h e development o f a new model f o r r a t e s and temperatures up t o 1100 "C. Also, b o t h s t a t i c r e c o v e r y . These c o n s i d e r a t i o n s were i n c o r p o - models were implemented i n t h e MARC n o n l i n e a r f i n i t e r a t e d i n a new c o n s t i t u t i v e model which was imple- element computer code w i t h t e s t cases r u n f o r a mented i n t o a f i n i t e element computer code. The code notched round t e n s i l e specimen and an a i r f o i l p o r t i o n was developed as a p a r t o f t h e c o n t r a c t s p e c i f i c a l l y o f a t y p i c a l c o o l e d t u r b i n e b l a d e .

f o r use w i t h u n i f i e d t h e o r i e s . The code was v e r i f i e d T y p i c a l r e s u l t s o f thermomechanical s t r a i n by a r e a n a l y s i s o f t h e t u r b l n e t i p d u r a b i l i t y problem c y c l i n g o f B1900+Hf m a t e r i a l a r e shown i n F i g s . 2 which was p a r t o f t h e pre-HOST a c t i v i t i e s a t General and 3. I n F i g . 2, we show a s i n g l e specimen c y c l e d t o E l ec tri c .

s a t u r a t i o n a t 538 "C, a temperature i n c r e a s e to 982 "C T y p i c a l of t h e many r e s u l t s o b t a i n e d from t h i s w i t h s a t u r a t e d loops achieved a t t h a t temperature, and e f f o r t a r e t h e m u l t i a x i a l thermomechanical comparisons "C, a l l under c o n s t a n t s t r a i n range a r e t u r n t o 538 shown i n F i g s . 5 and 6. F i g u r e 5 shows t h a t t h e new c o n t r o l . Two o b s e r v a t i o n s evidence absence o f thermal t h e o r y can p r e d i c t 90" out-of-phase t e n s i o n l t o r s i o n h i s t o r y e f f e c t . The h i g h - t e m p e r a t u r e e x c u r s i o n e x p e r i m e n t a l r e s u l t s a t e l e v a t e d temperature w i t h good r e s u l t e d i n n o change i n t h e h y s t e r e s i s l o o p a t 538 "C, accuracy. F i g u r e 6 shows a comparison o f p r e d i c t i o n and t h e c y c l i c s t r e s s range a s s o c i a t e d w i t h a g i v e n w i t h e x p e r i m e n t a l d a t a from combined temperature and c y c l i c s t r a i n was t h e same under t h i s t y p e o f noniso- s t r a i n c y c l i n g t e s t s . There i s r e a s o n a b l y good agree- thermal h i s t o r y as under s t r i c t l y i s o t h e r m a l c y c l i n g , ment between p r e d i c t i o n s and experiment c o n s i d e r i n g as shown i n F i g . 3. Both t y p e s of c y c l i n g agree w i t h t h e p r e d i c t i o n s a r e based o n l y on i s o t h e r m a l d a t a .

t h e Bodner-Partom model p r e d i c t i o n which i s based on i s o t h e r m a l d a t a o n l y .

The t h e o r y was implemented i n t o a new t h r e e - C . Note t h a t t h e t h a n u n l a x i a l t h r o u g h t h e parameter dimensional f i n i t e element code which uses a 20-noded h y s t e r e s i s l o o p l a b e l e d C = 10 i n d i c a t e s a c y c l i c b r i c k element. The program uses a dynamic t i m e i n c r e - response t h a t i s a b o u t 2 0 p e r c e n t s t r o n g e r t h a n t h e J2 response ( C = 0).

m e n t i n g p r o c e d u r e t o m i n i m i z e c o s t w h i l e g u a r a n t e e i n g F i g u r e 8 shows p r e d i c t i o n s o f c r e e p response, an a c c u r a t e s o l u t i o n . The i n e l a s t i c r a t e e q u a t i o n s i . e . , b e h a v i o r under c o n s t a n t s t r e s s . Here, t h e and s t a t e v a r i a b l e e v o l u t i o n e q u a t i o n s a r e i n t e g r a t e d u s i n g a second o r d e r Adams-Moulton p r e d i c t o r c o r r e c - s t r a i n - t i m e c u r v e l a b e l e d " u n i a x i a l and shear C = 0" r e p r e s e n t s b o t h t h e u n i a x i a l response ( u s i n g t h e tor t e c h n i q u e . Piecewise l i n e a r l o a d h i s t o r i e s a r e m o d e l l e d i n o r d e r t o s i m p l i f y i n p u t . F u r t h e r econom- s t r a i n s c a l e on t h e l e f t ) and t h e shear response f o r i c s have been achieved by i m p r o v i n g t h e s t a b i l i t y o f a J2 m a t e r i a l ( u s i n g t h e s t r a i n s c a l e on t h e r i g h t ) .

Each shear response c o r r e s p o n d i n g t o a p a r t i c u l a r the i n i t i a l s t r a i n method and f u r t h e r r e d u c i n g t h e v a l u e o f C i s to be measured u s i n g t h e r i g h t - h a n d number o f e q u i l i b r i u m i t e r a t i o n s .

I n summary, a new m u l t i a x i a l c o n s t i t u t i v e model shear s t r a i n s c a l e . I n creep, t h e e f f e c t o f t h e J3 which can r e p r e s e n t t h e complex n o n l i n e a r h i g h temper- dependence appears t o be more pronounced t h a n f o r f o r C = 10 t h e c r e e p s t r a i n a t u r e b e h a v i o r o f Ren6 80 was developed. The model s t r a i n c y c l i n g . Here, was e x t e n s i v e l y v e r i f i e d based on d a t a a t s e v e r a l t e m - a f t e r 100 h r d i f f e r s by a f a c t o r o f 2 f r o m t h a t f o r t h e J2 response ( C = 0).

p e r a t u r e s . The thermomechanical p r o p o r t i o n a l and non- p r o p o r t i o n a l c y c l i c m o d e l i n g c a p a b i l i t i e s o f t h e model were demonstrated. The model was implemented i n a A N I S O T R O P I C MATERIAL MODELING t h r e e - d i m e n s i o n a l s t r u c t u r a l a n a l y s i s f i n i t e element code and a t u r b i n e b l a d e was analyzed. u n i v e r s i t y o f C o n n e c t i c u t G r a n t N i c k e l - b a s e monocrystal s u p e r a l l o y s have been under development by t u r b i n e m a n u f a c t u r e r s f o r a U n i v e r s i t y o f Akron Grant number o f y e a r s . S u c c e s s f u l a t t e m p t s have now been Many v i s c o p l a s t i c c o n s t i t u t i v e models for h i g h - made under g r a n t NAG3-512, " C o n s t i t u t i v e M o d e l i n g o f t e m p e r a t u r e s t r u c t u r a l a1 loys a r e based e x c l u s l v e i y on S i n g l e C r y s t a l and D i r e c t i o n a l l y S o l i d i f i e d S u p e r a l - u n i a x i a l t e s t d a t a , as p r e v i o u s l y d i s c u s s e d . General- l o y s , " (Walker, and Jordan, 1987) t o model t h e defor- i z a t i o n t o m u l t i a x i a l s t a t e s o f s t r e s s i s made by m a t i o n b e h a v i o r o f these m a t e r i a l s based on b o t h a assuming t h e s t r e s s dependence t o be on t h e second macroscopic c o n s t i t u t i v e model and a micromechanical p r i n c i p a l I n v a r i a n t ( J 2 ) of t h e d e v i a t o r i c s t r e s s , f o r m u l a t i o n based on c r y s t a l l o g r a p h i c s l i p t h e o r y .

f r e q u e n t l y c a l l e d t h e " e f f e c t i v e " s t r e s s . T e s t i n g These models have been programmed as FORTRAN subrou- o t h e r t h a n u n i a x i a l , e.g., shear, b i a x i a l , e t c . , i s t i n e s under c o n t r a c t NAS3-23939 t o P r a t t and Whitney g e n e r a l l y done i n t h e s p i r i t o f v e r i f i c a t i o n t e s t i n g , and i n c l u d e d i n t h e MARC n o n l i n e a r f i n i t e element pro- n o t as p a r t of t h e d a t a base o f t h e model. I f such gram. They a r e c u r r e n t l y b e i n g used t o s i m u l a t e a J2 t h e o r y , based on u n i a x i a l t e s t i n g , i s c a l l e d thermal/mechanical l o a d i n g c o n d i t i o n s expected a t t h e upon t o p r e d i c t b e h a v i o r under c o n d i t i o n s o t h e r t h a n " f a t i g u e c r i t i c a l " l o c a t i o n s on a s i n g l e c r y s t a l (PWA u n i a x i a l , say p u r e shear, and i t does so p o o r l y , noth- 1480) t u r b i n e b l a d e . Such a n a l y s e s f o r m a n a t u r a l i n g i s l e f t t o a d j u s t i n t h e t h e o r y . The e x c l u s i v e p r e c u r s o r to t h e a p p l i c a t i o n o f l i f e p r e d i c t i o n dependence on J2 must be q u e s t i o n e d . For a f u l l y methods t o gas t u r b i n e a i r f o i l s .

i s o t r o p i c m a t e r i a l whose i n e l a s t i c d e f o r m a t i o n behav- The d i f f i c u l t y i n a n a l y z i n g t h e d e f o r m a t i o n behav- i o r i s r e l a t i v e l y independent o f h y d r o s t a t i c s t r e s s , i o r o f s i n g l e c r y s t a l m a t e r i a l s l i e s i n t h e i r a n i s o - t h e most g e n e r a l s t r e s s dependence i s on t h e two (non- t r o p i c b e h a v i o r . Two s e p a r a t e u n i f i e d v i s c o p l a s t i c z e r o ) p r i n c i p a l i n v a r i a n t s o f t h e d e v i a t o r i c s t r e s s , c o n s t i t u t i v e models f o r m o n o c r y s t a l PWA 1480 have been J2 and J3. These i n v a r i a n t s c o n s t i t u t e what i s c o m p l e t e l y f o r m u l a t e d . I n one model, t h e d i r e c t i o n a l known as an i n t e g r i t y b a s i s f o r t h e m a t e r i a l . p r o p e r t i e s o f t h e i n e l a s t i c d e f o r m a t i o n b e h a v i o r a r e Under NASA G r a n t NAG3-379. " A M u l t i a x i a l Theory a c h i e v e d by r e s o l v i n g t h e summed C r y s t a l l o g r a p h i c s l i p o f V i s c o p l a s t l c i t y f o r I s o t r o p i c M a t e r i a l s , " system s t r e s s e s and s t r a i n s o n t o t h e g l o b a l c o o r d i n a t e (Robinson, 1984) a time-dependent d e s c r i p t i o n poten- system. I n t h e o t h e r model, t h e , - e q u i r e d d i r e c t i o n a l t i a l f u n c t i o n based on c o n s t i t u t i v e t h e o r y w i t h s t r e s s p r o p e r t i e s a r e achieved by o p e r a t i n g on t h e g l o b a l dependence on J 2 and J3 t h a t reduces t o a known s t r e s s e s and s t r a i n s d i r e c t l y w i t h f o u r t h r a n k a n i s o - J2 t h e o r y as a s p e c i a l case was developed. The char- t r o p y t e n s o r s . The c r y s t a l l o g r a p h i c s l i p based model a c t e r i z a t i o n of v i s c o p l a s t i c i t y can be made l a r g e l y on i s more a c c u r a t e and has more p h y s i c a l s i g n i f i c a n c e u n i a x i a l t e s t i n g b u t t h e " s t r e n g t h " o f t h e J3 depend- i s more computation- t h a n t h e macroscopic model, b u t ence must be d e t e r m i n e d by t e s t i n g o t h e r t h a n u n i a x - a l l y i n t e n s i v e t h a n i t s macroscopic c o u n t e r p a r t .

i a l , e . g . , p u r e shear. The m a t e r i a l c o n s t a n t s i n b o t h models can be Several c a l c u l a t i o n s have been made u s i n g forms o b t a i n e d from u n i a x i a l t e s t s on ~ 0 0 1 )and < 1 1 1 > of t h e f u n c t i o n s i n t h e model and a s s o c i a t e d m a t e r i a l o r i e n t e d u n i a x i a l specimens, o r from u n i a x i a l and t o r - parameters t h a t a r e t y p i c a l o f f e r r i t i c chrome-based s i o n t e s t s on <001> o r i e n t a t e d t u b u l a r specimens.

and a u s t e n i t i c s t a i n l e s s - s t e e l a l l o y s . Q u a l i t a t i v e l y Both models a c h i e v e good c o r r e l a t i o n w i t h t h e e x p e r i - s i m i l a r r e s u l t s can be expected for n i c k e l - b a s e d mental d a t a i n t h e t o o l > and < 1 1 1 > c o r n e r s o f t h e a l l o y s . F i g u r e 7 shows p r e d i c t e d h y s t e r e s i s l o o p s s t e r e o g r a p h i c t r i a n g l e , and b o t h models c o r r e c t l y p r e - o v e r a c o n s t a n t s t r a i n range (Ac = 0.6 p e r c e n t ) and d i c t t h e d e f o r m a t i o n b e h a v i o r o f specimens o r i e n t a t e d s t r a i n r a t e ( E = 0.001/m). The c u r v e l a b e l e d " u n i a x - i n t h e <011> d i r e c t i o n . The t e n s i o n - t o r s i o n t e s t s on i a l " can be t h o u g h t of as h a v i n g been c a r e f u l l y f i t on t u b u l a r specimens o r i e n t a t e d i n t h e <001> d i r e c t i o n t h e b a s i s o f u n i a x i a l d a t a . P r e d i c t i o n s o f p u r e shear were c a r r i e d o u t a t a t e m p e r a t u r e o f 870 " C (1600 O F ) response a r e a l s o shown, c o r r e s p o n d i n g t o d i f f e r e n t a t t h e U n i v e r s i t y o f C o n n e c t i c u t . F u r t h e r t e s t s a t v a l u e s o f C. A J2, J3 t h e o r y reduces t o a J2 t e m p e r a t u r e s r a n g i n g f r o m room temperature t o 1149 "C t h e o r y for C = 0. Even a f t e r t e d i o u s f i t t i n g o f u n i - (2100 O F ) have been c a r r i e d o u t a t P r a t t and Whitney i f t h e shear p r e d i c t i o n does n o t a x i a l c y c l i c d a t a , under c o n t r a c t NAS3-23939. Good c o r r e l a t i o n s and p r e - c o r r e l a t e w e l l w i t h shear d a t a , n o t h i n g can be done i n d i c t i o n s a r e u n i f o r m l y a c h i e v e d a t t e m p e r a t u r e s above a 32 t h e o r y s h o r t o f compromising t h e u n i a x i a l c o r - 649 " C (1200 O F ) , b u t f u r t h e r work appears t o be nec- r e l a t i o n s . The p r e s e n t J2, J3 t h e o r y a l l o w s some e s s a r y t o c o r r e c t l y model t h e d e f o r m a t i o n b e h a v i o r o f f l e x i b i l i t y i n a c c u r a t e l y p r e d i c t i n g response o t h e r P W A 1480 m o n o c r y s t a l m a t e r i a l below 649 " C (1200 " F ) .

The starting point for the theoretical develop- University of Cincinnati Grant Nickel base single crystal superalloys have ment is the assumed existence of a dissipation poten- attracted considerable interest f o r use in gas turbine tial function R f o r a composite material; that is a jet engine because of their superior high temperature two constituent (fiber/matrix), pseudohomogeneous material.

properties. In polycrystalline turbine parts, rupture The potential function is of the form is usually due t o crack propagation originating at the grain boundaries. Since single crystal alloys have n o (1) grain boundaries, use of the alloy has significant R = !Xuij, aij, didj. T) advantages f o r increased strength and longer life.

Under grant NAG3-511, "Anisotropic Constitutive in which ui denotes the components of (Cauchy) Modeling f o r Nickel-Base Single Crystal Alloy Renk stress, a the components of a tensorial internal N4," an anisotropic constitutive model was developed !j state variable (internal stress), did the components based o n a crystallographic approach. The current of a directional tensor, and T the iemperature. The equations modified a previous model proposed by Dame of symmetric tensor did4 is formed by a self product and Stouffer (1986) where a Bodner-Partom equation the unit vector di enoting the local fiber direc- with only the drag stress was used t o model the local tion. Account can be taken of more than a single fam- inelastic response in each slip system. Their model ily of fibers inherent t o the continuum element.

was considered successful for predicting both the The present theory has been implemented into the orientation dependence and tension/compression asymme- commercial finite element code MARC. Several trial try for tensile and creep histories f o r single crystal calculations have been made under uniaxial conditions alloy RenC N4 at 760 "C (1400 Of). However, certain using material functions and parameters that approxi- properties including fatigue were not satisfactorily

mate a tungsten/copper composite material. A trans-

modeled. A back stress state variable was incorpo- versely isotropic continuum elasticity theory has been rated into the local slip flow equation based o n the used in conjunction with the present viscoplastic observed experimental observations. Model predicta- theory. The results of the calculations show the bility was improved especially for mechanical proper- expected responses of rate-dependent plasticity, creep, ties such as inelasticity and fatigue loops.

and relaxation as well as appropriate anisotropic fea- Figures 9 and 1 0 are typical of the numerous tures. Predictions of relaxation and hysteresis loops results obtained from this effort. Experimental data for different fiber orientation angles o n a tungsten/ and predicted responses of tensile and cyclic condi- copper like material are shown in Figs. 1 1 and 1 2 .

tions for different specimen orientations are compared.

Shown in Fig. 9 are the experimental data in C 1 0 0 1 and [ 1 1 1 1 orientations which were used to determine mate- COMPUTATIONAL METHODS AND CODE DEVELOPMENT rial constants. The response in [1101 orientation is the predicted result. The model predicted very well General Electric Contract the elastic moduli, hardening characteristics (the It has become apparent in recent years that there knee of the curves) and the saturated values. In is a serious problem of interfacing the output temper- Fig. 10, comparisons show the model predicts very well atures and temperature gradients from either the heat the cyclic tension/compression asymmetry, hardening transfer codes o r engine tests with the input t o the characteristics and rate effect for the ClOOl orienta- stress analysis codes. With the growth in computer tion. The prediction of the hystersis I m p was based postprocessors, the analysis of hot section components solely o n saturated constants determined from tensile using hundreds and even thousands of nodes in the heat tests.

transfer and stress models has become economical and routine. This has exacerbated the problem of manual University of Akron Grant transfer of output three-dimensional temperatures from Structural alloys used in high-temperature appli- heat transfer codes to stress analysls input to where cations exhibit compiex thermomechanical behavior that the engineering effort required is comparable t o that is time-dependent and hereditary. Recent attention is required for the remainder of the analysis. Further- being focused o n metal-matrix composite materials for

more, a considerable amount o f approximation has been

aerospace applications that, a t high temperature, introduced in an effort to accelerate the process.

exhibit all the complexities o f conventional alloys This tends to introduce errors into the temperature (e.g., creep, relaxation, recovery, rate sensitivity) data which negates the improved accuracy in the tem- and, in addition, exhibit further complexities because perature distribution achieved through use of a fine of their strong anisotropy.

mesh. There is, then, a strong need for an automatic Under grant NAG3-379. "A Continuum Deformation thermal interface module. A module was developed Theory for Metal-Matrix Composites at High Tempera- under contract NAS3-23272, "Burner Liner Thermal/ ture," (Robinson e t al., 1986) a continuum theory was Structural Load Modeling," (Maffeo, 1984).

developed for representing the high-temperature, The overall objectives of this thermal/structural time-dependent, hereditary deformation behavior of transfer module were that it handle independent mesh metallic composites that can be idealized as pseudo- configurations, finite difference and finite element homogeneous continua with locally definable direc- heat transfer codes, perform the transfer in an accu- tional characteristics. Homogenization of textured materials (molecular, granular, fibrous) and aDplica- rate and efficient fashion and the total system be flexible for future applications. Key features of the bility of continuum mechanics in structural applica- code developed include: independent heat transfer and tions depends o n characteristic body dimensions, the of thermal data, severity of gradients (stress, temperature, etc.) in stress model meshes, accurate transfer computationally efficient transfer, user friendly pro- the structure and o n the relative size of the inter- gram, flexible system, internal coordinate transforma- nal structure (cell size) of the material. Examina- tions, automated exterior surfacing techniques and tion reveals that the appropriate conditions are met geometrical and temporal windowing capability.

in a significantly large class of anticipated aero-

A schematic of the TJansfer AJalysis c o d e (TRAN- of metallic composites t o justify space applications CITS) is shown in fig. 13. The module can process research into the formulation of continuum-based heat transfer results directly from the MARC (finite theor i e s .

element) and S I N D A ( f i n i t e d i f f e r e n c e ) programs and o f d e f a u l t n u m e r i c a l v a l u e s a r e s t o r e d f o r these The u s e r need o n l y i n p u t v a l u e s f o r those w i l l o u t p u t temperature i n f o r m a t i o n i n t h e forms parameters.

These r e q u i r e d f o r MARC and NASTRAN. The i n p u t and o u t p u t parameters which a r e t o have d i f f e r e n t v a l u e s .

com- r o u t i n e s i n t h e module a r e v e r y f l e x i b l e and c o u l d r e c i p e parameters t h e n u n i q u e l y d e f i n e a g e n e r i c e a s i l y be m o d i f i e d t h r o u g h a n e u t r a l f i l e t o e x c e p t ponent w i t h t h e d e f i n e d dimensions. The s o f t w a r e d a t a from o t h e r h e a t t r a n s f e r codes and f o r m a t d a t a l o g i c t h e n works w i t h these parameters t o develop a t o o t h e r s t r e s s a n a l y s i s codes. f i n i t e element model o f t h i s geometry c o n s i s t i n g o f T h i s t h e r m a l l o a d t r a n s f e r module has been shown 20-noded i s o p a r a m e t r i c elements. The u s e r s p e c i f i e s to e f f i c i e n t l y and a c c u r a t e l y t r a n s f e r thermal d a t a t h e number and d i s t r i b u t i o n o f t h e s e elements t h r o u g h f r o m d i s s i m i l a r h e a t t r a n s f e r meshes t o s t r e s s meshes. i n p u t c o n t r o l parameters. F i g u r e 14 shows t h e g e n e r i c The fundamental p a r t o f t h e code, t h e t h r e e - d i m e n s i o n a l geometry and r e c i p e for a combustor l i n e r p a n e l .

search, i n t e r p o l a t i o n and s u r f a c i n g r o u t i n e s , have much more p o t e n t i a l . They form an o u t s t a n d i n g f o u n d a t i o n ( 4 ) The subsystem which p e r f o r m s t h e t h r e e - f o r a u t o m a t i c c o n s t r u c t i o n of embedded meshes, l o c a l dimensional n o n l i n e a r f i n i t e element a n a l y s i s o f t h e element mesh r e f i n e m e n t , and t h e t r a n s f e r o f o t h e r h o t s e c t i o n component model and was developed under mechanical t y p e l o a d i n g . t h e NASA HOST c o n t r a c t NAS3-23698, " t h r e e - d i m e n s i o n a l I n e l a s t i c A n a l y s i s Methods for Hot S e c t i o n S t r u c t u r e s . " T h i s s o f t w a r e p e r f o r m s i n c r e m e n t a l n o n l i n e a r f i n i t e General E l e c t r i c C o n t r a c t element a n a l y s i s o f complex t h r e e - d i m e n s i o n a l s t r u c - The o v e r a l l o b j e c t i v e of t h i s program was t o t u r e s under c y c l i c thermomechanical l o a d i n g w i t h tem- develop and v e r i f y a s e r i e s o f i n t e r d i s c i p l i n a r y p e r a t u r e dependent m a t e r i a l p r o p e r t i e s and m a t e r i a l modellng and a n a l y s i s t e c h n i q u e s s p e c i a l i z e d t o response b e h a v i o r . The n o n l i n e a r a n a l y s i s c o n s i d e r s address h o t s e c t i o n components. These t e c h n i q u e s b o t h time-independent and time-dependent m a t e r i a l i n c o r p o r a t e d a t a as w e l l as t h e o r e t i c a l methods f r o m b e h a v i o r . Among t h e c o n s t i t u t i v e models a v a i l a b l e i s many d i v e r s e areas i n c l u d i n g c y c l e and performance t h e H a i s l e r - A l l e n c l a s s i c a l model which p e r f o r m s p l a s - a n a l y s i s , h e a t t r a n s f e r a n a l y s i s , l i n e a r and n o n l i n - t i c i t y a n a l y s i s w i t h i s o t r o p i c m a t e r i a l response, e a r s t r e s s a n a l y s i s , and m i s s i o n a n a l y s i s . B u i l d i n g k i n e m a t i c m a t e r i a l response, or a c o m b i n a t i o n o f iso- on t h e p r o v e n t e c h n i q u e s a l r e a d y a v a i l a b l e i n these t r o p i c and k i n e m a t i c m a t e r i a l response. T h i s i s com- f i e l d s , t h e new methods developed t h r o u g h t h i s con- b i n e d w i t h a c l a s s i c a l creep a n a l y s i s f o r m u l a t i o n . A t r a c t were i n t e g r a t e d i n t o a system which p r o v i d e s an major advance i n t h e a b i l i t y t o p e r f o r m time-dependent a c c u r a t e , e f f i c i e n t , and u n i f i e d approach t o a n a l y z - analyses i s a dynamic t i m e i n c r e m e n t i n g s t r a t e g y i n g h o t s e c t i o n s t r u c t u r e s . The methods and codes i n c o r p o r a t e d i n t h i s s o f t w a r e .

developed under t h i s c o n t r a c t , NAS3-23687, "Component- S p e c i f i c Modeling," (McKnight, 1985) p r e d i c t tempera- ( 5 ) The COSMO system which c o n s i s t s o f an execu- t u r e s , d e f o r m a t i o n , s t r e s s and s t r a i n h i s t o r i e s t i v e module which c o n t r o l s t h e TDEM, TDLM, t h e geomet- t h r o u g h o u t a complete f l i g h t m i s s i o n . r i c modeler, t h e s t r u c t u r a l a n a l y s i s code, t h e f i l e and c e r t a i n a n c i l l a r y modules.

F i v e b a s i c modules w e r e developed and t h e n l i n k e d s t r u c t u r e / d a t a base, t o g e t h e r w i t h an e x e c u t i v e module. They a r e : The a n c i l l a r y modules c o n s i s t o f a band w i d t h o p t i - m i z e r module, a deck g e n e r a t i o n module, a r e m e s h i n g l ( 1 ) The lhermodynamic Engine Model (TDEM) which mesh r e f i n e m e n t module and a p o s t p r o c e s s i n g module.

i s t h e subsystem of computer software. I t t r a n s l a t e s The e x e c u t i v e d i r e c t s t h e r u n n i n g o f each module, con- a l i s t o f m i s s i o n f l i g h t p o i n t s and d e l t a t i m e s i n t o t r o l s t h e f l o w o f d a t a among modules and c o n t a i n s t h e t i m e p r o f i l e s o f major engine performance parameters. s e l f a d a p t i v e c o n t r o l l o g i c . F i g u r e 15 i s a flow c h a r t I t s p r e s e n t d a t a base c o n t a i n s CF6-5OC2 e n g i n e p e r - o f t h e COSMO system showing d a t a flow and t h e a c t i o n formance d a t a . I n o r d e r t o adapt t h i s system t o a p o s i t i o n s o f t h e a d a p t i v e c o n t r o l s . The modular d e s i g n d i f f e r e n t e n g i n e r e q u i r e s o n l y t h e r e s t o c k i n g o f t h i s o f t h e system a l l o w s each subsystem t o be viewed as a d a t a base w i t h t h e a p p r o p r i a t e e n g i n e performance p l u g - i n module. They can be a b s t r a c t e d and r u n a l o n e d a t a . or r e p l a c e d w i t h a l t e r n a t e systems.

The i d e a s , t e c h n i q u e s , and computer s o f t w a r e ( 2 ) The I h e r m o b n a m i c Loads Model (TDLM) which i s developed i n t h e Component S p e c i f i c M o d e l i n g program t h e subsystem o f computer s o f t w a r e which works w i t h have proven to be e x t r e m e l y v a l u a b l e i n advancing t h e t h e o u t p u t o f t h e TDEM to produce t h e m i s s i o n c y c l e p r o d u c t i v i t y and d e s i g n - a n a l y s i s c a p a b i l i t y f o r h o t l o a d i n g on t h e i n d i v i d u a l h o t s e c t i o n components. s e c t i o n s t r u c t u r e s .

There a r e s e p a r a t e segments for t h e combustor, t h e t u r b i n e b l a d e , and t h e t u r b i n e vane. These segments t r a n s l a t e t h e m a j o r e n g i n e performance parameter p r o - General E l e c t r i c C o n t r a c t f i l e s from t h e TDEM i n t o p r o f i l e s o f t h e l o c a l thermo- Under NASA c o n t r a c t NAS3-23698, "Three-Dimensional dynami c l o a d s ( p r e s s u r e s , temperatures, rpm) f o r each I n e l a s t i c A n a l y s i s Methods f o r Hot S e c t i o n Compo- component. The f o r m u l a s which p e r f o r m t h i s mapping i n n e n t s , " (McKnight e t a l . . 1986), a s e r i e s o f t h r e e - t h e TDLM models were developed for t h e s p e c i f i c engine dimensional i n e l a s t i c s t r u c t u r a l a n a l y s i s computer components. To adapt these models t o a d i f f e r e n t codes were developed and d e l i v e r e d t o NASA Lewis.

engine would r e q u i r e e v a l u a t i n g these f o r m u l a s for The o b j e c t i v e o f t h i s program was t o develop a n a l y t i - t h e i r s i m u l a t i o n c a p a b i l i t y and making any necessary c a l methods capable o f e v a l u a t i n g t h e c y c l i c time- changes. dependent i n e l a s t i c i t y which o c c u r s i n h o t s e c t i o n engine components. Because o f t h e l a r g e e x c u r s i o n s i n ( 3 ) The Component S p e c i f i c S t r u c t u r a l M o d e l i n g temperature a s s o c i a t e d w i t h h o t s e c t i o n engine compo- which i s t h e h e a r t o f t h e geometric m o d e l i n g and mesh n e n t s , t h e techniques developed must be a b l e t o accom- g e n e r a t i o n u s i n g t h e r e c i p e concept. A g e n e r i c geome- modate l a r g e v a r i a t i o n s i n m a t e r i a l b e h a v i o r i n c l u d i n g t r y p a t t e r n i s determined f o r each component. A p l a s t i c i t y and creep. To meet t h i s o b j e c t i v e , General r e c i p e i s developed f o r t h i s b a s i c geometry i n terms E l e c t r i c developed a m a t r i x c o n s i s t i n g o f t h r e e con- o f p o i n t c o o r d i n a t e s , l e n g t h s , t h i c k n e s s e s , a n g l e s , s t i t u t i v e models and t h r e e element f o r m u l a t i o n s . A and r a d i i . These r e c i p e parameters a r e encoded i n s e p a r a t e program for each c o m b i n a t i o n of c o n s t i t u t i v e computer software as v a r i a b l e i n p u t parameters. A s e t model-element model was w r i t t e n , making a t o t a l o f stress-strain response and glosses over the complica- nine programs. Each program was given a stand alone tions associated with strain rate effects, etc. The capability of performing cyclic nonlinear analysis.

state-of-the-art model partitions time-independent The three constitutive models are in three dis- plasticity and time-dependent creep in the conven- tinct forms: a simplified theory (simple model), a tional way, invoking the von Mises yield criterion classical theory, and a unified theory. In an inelas- and standard (isotropic. kinematic, combined) harden- tic analysis, the simplified theory uses a bilinear

ing rules f o r the former, and a power law f o r the lat-

stress-strain curve t o determine the plastic strain ter. Walker's viscoplasticity theory which accounts and a power law equation to obtain the creep strain.

for the interaction between creep/relaxation and plas- of Haisler The second model is the classical theory ticity that occurs under cyclic loading conditions, and Allen. The third mode1 is the unified model of has been adopted as the advanced constitutive model.

Bodner and Partom. All of the models were programmed

MOMM - This is a stiffness method finite element

for a linear variation of loads and temperatures with code that utilizes one-. two- and three-dimensional the material properties being temperature dependent.

arrays of beam elements to simulate hot section compo- The three element formulations used are an 8-node nent behavior. Despite limitations of such beam model isoparametric shell element, a 9-nc3e shell element, representations, the code will be useful during early and a 20-node isoparametric solid element. The 8-node phases of component design as a fast, easy t o use.

element uses serendipity shape functions for interpo- computationally efficient tool. All of the structural lation and Gaussian quadrature for numerical integra- analysis types (static. buckling, vibration, dynam- tion. Lagrange shape functions are used in the 9-node ics). as well as the three constitutive models men- element. For numerical integration, the 9-node ele- tioned above, are provided by MOMM. Capabilities of ment uses Simpson's rule. The 20-node solid element the code have been tested for a variety of simple uses Gaussian quadrature for integration.

problem discretizations.

of structures, the nine For the linear analysis

MHOST - This code employs both shell and solid

codes use a blocked-column skyline, out-of-core equa- (brick) elements in a mixed method framework to pro- tion solver. T o analyze structures with nonlinear vide comprehensive capabilities f o r investigating material behavior, the codes use an initial stress local (stresslstrain) and global (vibration, buck- iterative scheme. Aitken's acceleration scheme was ling) behavior of hot section components. Attention incorporated into the codes t o increase the conver- was given to the development of solution algorithms, gence rate of the iteration scheme.

integration algorithms for stiffness, strain recovery The ability t o model piecewise linear load histo- and residual terms, and modeling methods that permit ries was written into the codes. Since the inelastic accurate representations of thermal effects o n struc- strain rate can change dramatically during a linear

tural loading and material properties, as well as geo-

load history, a dynamic time-incrementing procedure me tr i cal di scon t i nu i ti es .

was included. The maximum inelastic strain increment, The three constitutive models implemented are the maximum stress increment, and the maximum rate of secant elasticity model, von Mise's plasticity model, change of the inelastic strain rate are the criteria and Walker's creep plasticity model. Temperature

that control the size of the time step. The minimum

dependency and ani sotropy can be obtained through user time step calculated from the three criteria is the subroutines in MHOST. Nonlinear transient analysis value that is used.

and eigenvalue extraction for buckling and modal In dynamic analysis, the eigenvectors and elgen- analyses are some of the other important features in values can be extracted using either the determinant the program. The improved algorithm models and flnite search technique o r the subspace iteration method.

elements implemented in the code significantly reduced These methods are only included with those finite- CPU (Central Processing Units) time requirements for element codes containing the 8-node shell element.

three-dimensional analyses.

T o test the validity of the MHOST finite-element code, considerable efforts were made in applying the Pratt and Whitnev Aircraft Contract code in different cases with results compared to theo- The objective of the work done under contract retical predictions or numerical values generated by NAS3-23697. "Three-dimensional Inelastic Analysis other codes. For example, the code was used in-house Methods for Hot Section Components," (Nakazawa, 1987; to analyze a General Electric CF/6-50 engine blade and Wilson. and Banerjee. 1986) was t o produce three new rotor model with data generated by a computational computer codes t o permit accurate and efficient three- structural mechanics simulator system. The simulator dimensional inelastic analysis of combustor liners, system provided data, such as pressure and temperature turbine blades, and turbine vanes. The three codes distribution, centrifugal force, and time duration, at developed are called MOMM (Mechanics pf Materials various stages of flight. Figure 16 shows the varia- Model), MHOST (MARC-HOST) and BEST (Boundary flement tion of the radical displacement of the leading edge

- Stress Technology). These codes embody a progression

tip in the static condition during the entire flight of mathematical models f o r increasingly comprehensive without consideration of the centrifugal force effect.

of the geometrical features, loading representation

BEST3D - This is a general purpose three-

conditions, and forms of nonlinear material response dimensional structural analysis program utilizing the of hot section that distinguish the three groups boundary element method. The method has been imple- components.

mented for very general three-dimensional geometrles, of stand-alone codes was Software in the form and for elastic. inelastic and dynamic stress analy- developed by Pratt and Whitney Aircraft (PWA) with sis. Although the feasibility of many of the capabil- assistance from three subcontractors: MARC Analysis ities provided has been demonstrated in a number of Research Corporation (MARC), United Technology individual prior research efforts, the present code is Research Center (UTRC), and the State University of the first in which they have been made available f o r New York at Buffalo (SUNY-6).

large scale problems in a single code. In addition, Three increasingly sophisticated constitutive important basic advances have been made in a number of models were implemented in MOMM, MHOST, and BEST t o areas, including the development and implementation of account for inelastic material behavior (plasticity.

a variable stiffness plasticity algorithm, the Incor- creep) in the elevated temperature regime. The sim- poration of an embedded time algorithm for elastody- of plified model assumes a bilinear approximation namics and the extensive application of particular A k e y r e s u l t o f t h i s t e s t i n g e f f o r t was t h a t s u r - s o l u t i o n s w i t h i n t h e boundary element method. Major faces o f c o n s t a n t i n e l a s t i c s t r a i n r a t e e x i s t and can f e a t u r e s p r e s e n t l y a v a i l a b l e i n t h e BEST3D code i n c l u d e : v e r y g e n e r a l geometry d e f i n i t i o n , i n c l u d i n g be determined o r measured a t an e l e v a t e d temperature, 650 "C. This i s shown i n F i g . 19. The c o n c l u s i o n i s t h e use o f d o u b l e c u r v e d i s o p a r a m e t r i c s u r f a c e e l e - v a l i d a t e d o r deduced by t h e e x e c u t i o n o f t h e t e s t p r o - ments and volume c e l l s , w i t h p r o v i s i o n o f f u l l sub- s t r u c t u r i n g c a p a b i l i t y ; g e n e r a l c a p a b i l i t y f o r t h e grams and by t h e c o n s i s t e n c y o f t h e s u r f a c e r e s u l t s , e s p e c i a l l y t h e r e p e a t e d s u r f a c e s . To o u r knowledge, d e f i n i t i o n o f complex, time-dependent boundary condi- t i o n s ; c a p a b i l i t y f o r n o n l i n e a r a n a l y s i s u s i n g a t h i s i s t h e f i r s t s u c c e s s f u l d e t e r m i n a t i o n o f h i g h - temperature s u r f a c e s o f c o n s t a n t i n e l a s t i c s t r a i n v a r i e t y o f a l g o r i t h m s , s o l u t i o n procedures and c o n s t i - t u t i v e models; and a v e r y complete e l a s t o d y n a m i c capa- r a t e .

A l t h o u g h c o n c l u s i o n s r e g a r d i n g t h e e f f e c t of b i l i t y i n c l u d i n g p r o v i s i o n f o r f r e e v i b r a t i o n , f o r c e d response and t r a n s i e n t a n a l y s i s . these SCISRs d a t a on d i f f e r e n t t h e o r i e s w i l l be l e f t t o t h e c o n s t i t u t i v e e q u a t i o n d e v e l o p e r s , s e v e r a l I The BEST3D code was v a l i d a t e d by comparing pre- r e s u l t s can be s t a t e d . F i r s t , t h e s u r f a c e s d i d n o t d i c t i o n s from BEST3D w i t h t h o s e f r o m t h e o r e t i c a l move or change shape i n t h e a x i a l / t o r s i o n a l s t r e s s a n d / o r n u m e r i c a l p r e d i c t i o n s and some e x p e r i m e n t a l s t a t e by any s i g n i f i c a n t amount. Second, a d e d u c t i o n d a t a . For example, r e s u l t s f r o m a benchmark n o t c h t h a t p l a s t i c d e f o r m a t i o n s have a l a r g e r e f f e c t t h a n t e s t program were used. F i n i t e element and boundary creep d e f o r m a t i o n s can be s t a t e d . T h i r d , SCISRs element meshes f o r o n e - q u a r t e r o f a specimen gage sec- d e t e r m i n e d i m m e d i a t e l y a f t e r l a r g e p l a s t i c deforma- t i o n a r e shown i n F i g . 17. Measurements o f n o t c h r o o t t i o n show more i n c o n s i s t e n t r e s u l t s t h a n S C I S R s which s t r e s s - s t r a i n b e h a v i o r f o r i n i t i a l u p l o a d i n g s were have n o t undergone immediate p r i o r p l a s t i c deforma- compared w i t h p r e d i c t i o n s ( F i g . 18). S i m u l a t i o n o f t i o n s . L a s t , t h e extensometer system and s o f t w a r e f i r s t - c y c l e n o t c h root b e h a v i o r w i t h BEST3D was proven c o n t r o l system performed e x t r e m e l y w e l l i n a d i f f i - t o be q u i t e a c c u r a t e .

c u l t a p p l i c a t i o n .

EXPERIMENTAL FACILITIES AND DATA In-house Lewis Research C e n t e r E x p e r i m e n t a l Faci 1 i- t i e s and Data Oak Ridge N a t i o n a l L a b o r a t o r y I n t e r a g e n c y Agreement An e x o e r i m e n t a l e f f o r t was u n d e r t a k e n under U n i a x i a l Test Systems. Under HOST, r e c e n t expan- I n t e r a g e n c y Agreement Number 40-1447-84 and U.S. s i o n o f t h e u n i a x i a l t e s t i n g c a p a b i l i t y o f t h e f a t i g u e Department o f Energy c o n t r a c t DE-AC05-840R 21400 w i t h and s t r u c t u r e s l a b o r a t o r y i n c l u d e d t h e a d d i t i o n o f M a r t i n M a r i e t t a Energy Systems I n c . . " D e t e r m i n a t i o n f o u r new t e s t systems ( B a r t o l o t t a , and McGaw, 1987).

One o f these systems i s shown i n F i g . 20. The l o a d o f S u r f a c e o f C o n s t a n t I n e l a s t i c S t r a i n Rate a t Ele- v a t e d Temperature," ( B a t t i s t e . and B a l l , 1986). r a t i n g for two o f t h e new systems i s 29072 k g (k20 000 l b ) . and t h e o t h e r two a t +22 680 k g S p e c i a l e x p l o r a t o r y m u l t i a x i a l d e f o r m a t i o n t e s t s on t u b u l a r specimens o f t y p e 316 s t a i n l e s s s t e e l a t (550 000 l b ) . Each system i s equipped w i t h a s t a t e - o f - t h e - a r t d i g i t a l c o n t r o l l e r . The d i g i t a l c o n t r o l - 649 " C (1200 O F ) were conducted t o i n v e s t i g a t e t i m e - l e r s have t h e a b i l i t y t o complete a smooth c o n t r o l dependent m a t e r i a l b e h a v i o r .

mode t r a n s f e r , which i s accomplished e i t h e r m a n u a l l y I n c l a s s i c a l p l a s t i c i t y t h e concept of y i e l d sur- o r e l e c t r o n i c a l l y . T h i s f e a t u r e w i l l make i t p o s s i b l e f a c e s i n m u l t i a x i a l s t r e s s space p l a y s a c e n t r a l r o l e , to conduct some o f t h e more complex t e s t s t h a t have n o t o n l y i n t h e d e f i n i t i o n o f i n i t i a l y i e l d i n g b u t i n been d e f i n e d by t h e c o n s t i t u t i v e model d e v e l o p e r s a t d e t e r m i n i n g subsequent p l a s t i c flow. A t h i g h tempera- NASA Lewis and elsewhere. Specimen h e a t i s p r o v i d e d t u r e s t h e d e f o r m a t i o n b e h a v i o r o f s t r u c t u r a l a l l o y s i s s t r o n g l y t i m e dependent. Consequently, t h e s i g n i f i - by 5 k W r a d i o f r e q u e n c y i n d u c t i o n h e a t e r s . A x i a l s t r a i n s a r e measured u s i n g an a x i a l extensometer. To cance o f y i e l d s u r f a c e s b r e a k s down, and i t has been s t u d y t h e e f f e c t s of t h e environment on c r e e p - f a t i g u e proposed t h a t i n t h e i r p l a c e t h e concept o f s u r f a c e s b e h a v i o r , t h e two s m a l l e r l o a d c a p a c i t y t e s t systems o f c o n s t a n t i n e l a s t i c s t r a i n r a t e ( S C I S R ) m i g h t be chambers c a p a b l e o f u t i l i z e d . Such s u r f a c e s , c a l l e d SCISRs. can be shown a r e equipped w i t h e n v i r o n m e n t a l p r o v i d i n g a vacuum a n d / o r an i n e r t environment. The t o have a p o t e n t i a l n a t u r e and t h u s c o n s t i t u t e t h e b a s i s o f a r a t i o n a l m u l t i a x i a l v i s c o p l a s t i c c o n s t i t u - e n v i r o n m e n t a l chamber i s a b l e t o s u s t a i n a vacuum o f t i v e t h e o r y . 2 . 6 7 ~ 1 0 - ~ Pa (2x10-6 t o r r ) w i t h a specimen temperature A s u r f a c e o f c o n s t a n t i n e l a s t i c s t r a i n r a t e was o f 1093 " C (2000 O F ) . A l l systems i n c l u d e w a t e r - c o o l e d h y d r a u l i c g r i p s f o r s i m p l e specimen i n s t a l l a - determined b y l o a d i n g t h e specimen a t a c o n s t a n t e f f e c t i v e s t r e s s r a t e i n t h e two-dimensional a x i a l / t i o n . By t h e means o f exchanging two c o l l e t s these t o r s i o n a l s t r e s s s t a t e i n v a r i o u s d i r e c t i o n s u n t i l a g r i p s can be adapted t o h a n d l e e i t h e r f l a t b a r , smooth p r e d e t e r m i n e d i n e l a s t i c e f f e c t i v e s t r a i n r a t e was shank, o r threaded-end specimens. Each u n i a x i a l sys- reached. A f t e r each probe, t h e s t r e s s was r e t u r n e d t o tem has i t s own minicomputer f o r e x p e r i m e n t a l c o n t r o l t h e i n i t i a l s t a r t i n g p o i n t ; t h u s a l o c u s o f p o i n t s and d a t a a c q u i s i t i o n . P r e l i m i n a r y s o f t w a r e has been ( s u r f a c e o f c o n s t a n t i n e l a s t i c s t r a i n r a t e ) was developed by t h e e x p e r i m e n t a l i s t s t o conduct t e s t s as e s t a b l i s h e d . s i m p l e as a low c y c l e f a t i g u e t e s t , and as c o m p l i c a t e d Two t y p e s o f t e s t s were conducted. One t e s t as thermomechanical t e s t s .

specimen was s u b j e c t e d t o a time-independent t o r s i o n a l shear s t r a i n t e s t h i s t o r y , and surfaces o f c o n s t a n t B i a x i a l T e s t Systems. I n many l i f e and m a t e r i a l i n e l a s t i c s t r a i n r a t e ( S C I S R s ) i n an a x i a l / t o r s i o n a l b e h a v i o r models, m u l t i a x i a l r e p r e s e n t a t i o n s a r e formu- s t r e s s space were measured a t v a r i o u s p r e d e t e r m i n e d l a t e d b y m o d i f y i n g u n i a x i a l c r i t e r i a . U n f o r t u n a t e l y , p o i n t s d u r i n g t h e t e s t . A second specimen was sub- t h i s method does n o t always a c h i e v e t h e a c c u r a c y needed I n j e c t e d t o a 14-week time-dependent (creep-recovery- t o meet d e s i g n g o a l s o f h o t s e c t i o n components.

creep p e r i o d s ) t o r s i o n a l shear s t r e s s h i s t o g r a m . response t o t h i s need for b e t t e r l i f e and m a t e r i a l SCISRs d e t e r m i n a t i o n s were made a t 17 p o i n t s d u r i n g b e h a v i o r p r e d i c t i o n s under complex s t a t e s o f s t r e s s t h e t e s t . The t e s t s were conducted i n a h i g h - and s t r a i n , a m u l t i a x i a l t e s t i n g c a p a b i l i t y i s b e i n g t e m p e r a t u r e , c o m p u t e r - c o n t r o l l e d a x i a l / t o r s i o n a l t e s t developed. As an e v o l u t i o n a r y s t e p from a u n i a x i a l t e s t c a p a b i l i t y , a d e c i s i o n was made t o b e g i n w i t h f a c i l i t y u s i n g an Oak Ridge N a t i o n a l L a b o r a t o r y d e v e l - b i a x i a l ( a x i a l - t o r s i o n ) t e s t systems ( F i g . 21) and oped h i g h - t e m p e r a t u r e m u l t i a x i a l extensometer.

eventually progress to triaxial systems through the mechanical strain rate were similar to what was used use of internal pressure. Under HOST, three new biax- for the isothermal experiments. Because of the tem- ial test systems were added to the laboratory perature response limitations of the experiment (Bartolotta, and McGaw, 1987). itself, it should be noted that at the tensile peaks of each thermomechanical cycle, the temperature under- The load frames f o r each test system are rated for loads of 5 2 2 948 k g (550 000 lb) axial and shot its lower bound by -5 "C (195 "C instead of 200 "0.

-2824 N-m ( 2 2 5 000 in.-lb) torsional. Electronics From Fig. 2 2 it can be observed that at the tenth for these systems consist of two servocontrollers,

of the isothermal tests the stress - inelastic

two data display units, function generators, and an cycle strain responses are similar. A s f o r the thermome- oscilloscope. The two servocontrollers allow f o r

- inelastic strain response

both independent and combined control of axial and chanical test, the stress i s slightly different compared t o the isothermal data.

torsional loading. Each servocontroller can control

is probably due to the difference in mechanical

specimen loading in one of three modes: load, strain This or stroke for axial loading and torque, torsional strain range caused by the temperature overshoot. A s

can be seen, the stress - inelastic strain response

strain o r angular displacement for torsional loading.

Data display units are used to monitor analog data for the thermomechanical experiments seems t o follow of the lower temperature isothermal signals, and provide an important interface between more closely that the test system and the computer system. These units test. A s cycling continues, the thermomechanical of can be programmed t o perform a variety of signal pro- material response seems t o start following that cessing operations. the higher temperature isothermal experiment. This The heating system for each biaxial test system observation was also observed in another thermomechan- ical experiment (400 to 600 " C ) . which suggests that consists of an audio frequency induction generator, this trend is a general material hardening character- an induction coil fixture, and a PID controller for istic, but further investigation will have to be con- closed-loop temperature control. Each generator has a power output of 50 k W at an operating frequency of ducted before this can be confirmed.

Preliminary inelastic strain comparisons between 9.6 kHz. Audio frequency generators were chosen isothermal and thermomechanical experimental data have because o f their ability t o operate with minimal elec- proven useful in developing a better understanding of trical interference to instrumentation signals.

thermomechanical material response f o r Hastelloy-X.

Each axial-torsional test system is interfaced with its own minicomputer. These minicomputers, along From these types o f comparisons it appears that with the data display units, are used for experimental general thermcmechani cal material behavior can be control and data acquisition. Preliminary software i s extracted from isothermal experimental data, but being used to conduct simple tests, while more compli- information concerning changes in material strain har- dening behavior must come from thermcmechanical test cated test programs are still in their developmental data.

stages.

Tests o n Haynzs 188, a cobalt-based superalloy A thin-walled tube was chosen as the basic speci- men gecmetry. This type of geometry has the following used in hot section component applications were also advantages: (a) easy decomposition of axial-torsional conducted in the laboratory (Ellis e t al.. 1987). An example of the test results obtained is presented. In components of stress and strain, (b) a t high tempera- this example we are concerned with determining the tures thermal gradients across the diameter are mini- stress levels o r "thresholds" at which creep deforma- mal, and (c) f o r thermomechanical testing, cooling tions first become significant in Haynes 188 over a rates are higher.

temperature range of interest. A second series of experiments was conducted to establish whether the Uniaxial Exoerimental Results. Extensive data- thresholds determined under monotonic conditions also bases for several materials have been generated under apply in the case of thermomechanical loading.

the grants and contracts previously discussed. In A s shown in Table 1 1 , the threshold experiments the Lewis Fatigue and Structures Laboratory, a uniax- showed the expected result that early creep response ial database on Hastelloy-X, a nickel-base superalloy is strongly temperature dependent. It can be seen used in hot section component applications, was gener- that at 649 " C , stress levels must exceed 207 MPa ated (Bartolotta. 1985; Ellis et al., 1986; (30 ksi) before creep strains become significant Bartolotta, and Ellis, 1987). These data are being during the 1.5 hr hold periods. At temperatures of used in the development and calibration of constitutive 7 6 0 and 871 " C , the corresponding values of stress models. In addition, some of the data generated was are 75.9 MPa ( 1 1 ksi) and 27.6 MPa (4 ksi), respec- used to address a number of questions regarding the tively. One important point to be noted about this validity of methods adopted in characterizing the con- result i s that it would not have been predicted by stitutive models for particular high-temperature mate- inspection of handbook data. This is because mate- rials. One area of concern is that the majority of rial handbook; provide little o r n o information experimental data available for this purpose are regarding the early stages of creep. It follows that determined under isothermal conditions. This is in problems can arise if decisions regarding the need for contrast to service conditions which almost always inelastic analysis are based o n casual inspection of involve some form of thermal cycling. The obvious handbook data. The present study clearly indicated question arises as to whether a constitutive model that some form of inelastic analysis is necessary f o r characterized using an isothermal data base can ade- components operating at temperatures as high as 871 "C quately predict material response under thermomechanical if stress levels are expected to exceed 27.6 MPa conditions. Described here is an example of results (4 ksi).

of the most recent isothermal and thermomechanical Turning t o the results of the thermomechanical experiments conducted o n Hastelloy-X t o address this experiments o n Haynes 188, ratchetting behavior can be concern.

observed in the data shown in Fig. 2 3 for a mean Results obtained from two uniaxial isothermal stress of 42.5 MPa (6.17 ksi). In this case, the (205 and 425 " C ) and one out-of-phase uniaxial ther- creep strain accumulated during cycle (1) was about momechanical (200 t o 400 " C ) experiments are presented 100 )IC. On subsequent cycles, the creep occurring per in Fig. 2 2 . The thermomechanical test was conducted in such a way that the mechanical strain range and m i c r o p r o c e s s o r , and t h e c o o l i n g a i r temperature and c y c l e was 50 p~ o r l e s s and t h e d a t a e x h i b i t e d c o n s i d - flow r a t e a r e a p p r o p r i a t e l y s e t so t h a t when combined, e r a b l e s c a t t e r . The r e a s o n for t h e s c a t t e r i s t h e t h e d e s i r e d thermal c y c l e i s imposed on a t e s t l i n e r .

e l e c t r i c a l n o i s e which c o m p l i c a t e d i n t e r p r e t a t i o n o f Thermocouples and an i n f r a r e d t h e r m o v i s i o n system t h e 42.5 MPa (6.17 k s i ) mean s t r e s s d a t a .

a r e used t o o b t a i n s u r f a c e temperatures on t h e t e s t The m a t e r i a l e x h i b i t e d c r e e p r a t c h e t t i n g d u r i n g l i n e r . There a r e p r o v i s i o n s for h a v i n g a t o t a l o f s i m u l a t e d s e r v i c e c y c l e s . T h i s r e s u l t was n o t p r e - 140 thermocouples on t h e t e s t l i n e r . Both thermocouple d i c t e d by a n a l y s i s u s i n g c u r r e n t c o n s t i t u t i v e models s i d e o f and thermal image d a t a a r e o b t a i n e d on t h e c o o l f o r Haynes 188.

t h e t e s t specimen. O n l y thermocouple d a t a a r e o b t a i n e d on t h e h o t s i d e ( f a c i n g t h e q u a r t z lamps) of t h e t e s t Lewis A n n u l a r Combustor L l n e r Test F a c i l i t y S t r u c t u r a l l i n e r . The thermocouple d a t a p r o v i d e temperatures a t Component Response Rig d i s c r e t e p o i n t s , w h i l e t h e i n f r a r e d system p r o v i d e s Segments, o r c y l i n d r i c a l s e c t i o n s of gas t u r b i n e d e t a i l e d maps o f c o o l - s i d e thermal i n f o r m a t i o n .

engine combustor l i n e r s were r a d i a n t l y heated i n t h e The thermal images o b t a i n e d f r o m t h e i n f r a r e d S t r u c t u r a l Component Response r i g shown i n F i g . 24.

camera a r e s t o r e d on a VHS t a p e r e c o r d e r , w i t h t h e Q u a r t z lamps were used t o c y c l i c a l l y h e a t t h e 2 0 - i n c l o c k t i m e superimposed on each image. Images o f t h e (0.5 m) d i a m e t e r t e s t l i n e r s . T h i s r e s u l t e d i n a x i a l t e s t specimen o f f r o m about 4 t o about 1 i n . i n diame- and c i r c u m f e r e n t i a l t e m p e r a t u r e v a r i a t i o n s as w e l l as t e r ( f o r f i n e r r e s o l u t i o n o f temperatures) can be t h r o u g h - t h e - t h i c k n e s s t e m p e r a t u r e g r a d i e n t s i n t h e t o t h o s e o f i n - s e r v i c e l i n e r s , and o b t a i n e d w i t h t h e zooming c a p a b i l i t y o f t h e i n f r a r e d t e s t l i n e r s i m i l a r system. T h i r t y thermal images a r e c a p t u r e d on t a p e t h u s s i m i l a r t h e r m a l l y induced s t r e s s e s and s t r a i n s .

A t y p i c a l engine m i s s i o n c y c l e ( t a k e - o f f . c r u i s e , e v e r y second. A computer system i s t h e n used t o p r o c - ess, reduce, enhance, and a n a l y z e t h e t r a n s i e n t tem- l a n d i n g , and t a x i ) o f 3 t o 4 h r was s i m u l a t e d i n 2 t o p e r a t u r e i n f o r m a t i o n . These d a t a a r e a l s o compared 3 min. The s i m u l a t e d c y c l i c temperatures and tempera- w i t h t h e thermocouple d a t a . Thermocouple d a t a a r e t u r e g r a d i e n t s were f e l t t o be adequate t o c a p t u r e used i n t h e c a l i b r a t i o n o f t h e i n f r a r e d system.

t h e time-independent and time-dependent i n t e r a c t i o n s D u r i n g a t e s t r u n b o t h t h e f a c i l i t i e s d a t a ( p r e s - r e s u l t i n g i n d e f o r m a t i o n as w e l l as t h e l o w - c y c l e sures f l o w s , power, e t c . ) and t h e r e s e a r c h d a t a ( p r i - thermal f a t i g u e phenomena o f i n - s e r v i c e l i n e r s . The m a r i l y t e m p e r a t u r e ) a r e a c q u i r e d f o r each t h e r m a l p r i m a r y purpose of t h e r i g was t o g e n e r a t e l a r g e q u a l - i t y thermomechanical databases on combustor l i n e r s c y c l e u s i n g t h e ESCORT I 1 d a t a a c q u i s i t i o n system a t Lewis. These d a t a a r e s t o r e d a u t o m a t i c a l l y once e v e r y (Thompson, and Tong, 1986).

second on a mainframe computer f o r l a t e r r e d u c t i o n and The t e s t program was a c o o p e r a t i v e e f f o r t w i t h a n a l y s i s .

P r a t t and Whitney A i r c r a f t (PWA), a d i v i s i o n o f U n i t e d Technologies Research, East H a r t f o r d , C o n n e c t i c u t .

PWA s u p p l i e d t h e t e s t r i g , which i n c l u d e d t h e q u a r t z lamp h e a t i n g system and s e v e r a l t e s t l i n e r s . Lewis L i n e r Tests and R e s u l t s p r o v i d e d t h e t e s t f a c i l i t y and had t h e r e s p o n s i b i l i - Two combustor l i n e r segments were t e s t e d i n t h e t i e s from i n t e g r a t i n g t h e t e s t r i g i n t o t h e t e s t S t r u c t u r a l Component Response R i g . F i r s t , a conven- f a c i l i t y up t o and i n c l u d i n g c o n d u c t i n g t h e t e s t s and t i o n a l l i n e r o f sheet metal seam-welded l o u v e r con- s t r u c t i o n from H a s t e l l o y - X m a t e r i a l ( F i g . 25) was a c q u i r i n g t h e data. Lewis and PWA p e r s o n n e l developed t e s t e d . Second, an advanced paneled l i n e r ( F i g . 25) automated computer c o n t r o l s t r a t e g i e s , d a t a a c q u i s i - t i o n systems, and methods f o r e f f i c i e n t d a t a r e d u c t i o n was t e s t e d .

A l a r g e , q u a l i t y (thermocouple (96 TC's) and I R ) and a n a l y s i s .

The q u a r t z lamp h e a t i n g system c o n s i s t s o f temperature database was o b t a i n e d on t h e c o n v e n t i o n a l 112-6-kVA lamps c o n f i g u r e d c i r c u m f e r e n t i a l l y i n 16 l i n e r . Some t y p i c a l thermocouple d a t a a r e shown i n F i g . 26. The c o r r e s p o n d i n g power h i s t o r y f o r t h e t h e r - s e c t o r s , each h a v i n g 7 lamps. T h i s system, i n a d d i - t i o n to d r a w i n g up t o 672 kVA o f 480-V power, r e q u i r e s mal c y c l e Is shown i n F i g . 27. F i g u r e 26 shows t h e 3.5 I b l s e c of ambient t e m p e r a t u r e a i r a t 5 p s i g , t r a n s i e n t temperature response a t t h r e e l o c a t i o n s on 1.5 l b / s e c a m b i e n t t e m p e r a t u r e a i r a t 1 p s i g and l o u v e r 5. The temperature measurements a r e used i n 80 g a l l m i n of s p e c i a l l y t r e a t e d w a t e r f o r c o o l i n g t h e t h e h e a t t r a n s f e r l s t r u c t u r a l a n a l y s i s of t h e l i n e r .

r i g . The l i n e r was t h e r m a l l y c y c l e d for a l m o s t 1800 c y c l e s . Between 1500 and 1600 c y c l e s an a x i a l c r a c k A n a t u r a l - g a s and a i r m i x t u r e i s burned i n a com- b u s t o r can upstream o f t h e t e s t s e c t i o n t o p r o v i d e about 0.2 i n . i n l e n g t h developed i n t h e l i n e r . T h i s c r a c k o c c u r r e d a t a h o t s p o t which developed because preheated c o o l i n g a i r t o t h e t e s t l i n e r . C o o l i n g a i r temperatures a r e c o n t r o l l a b l e from 205 t o 316 O C (400 t o o f c l o s u r e o f s e v e r a l c o o l i n g h o l e s . There was no thermocouple r i g h t a t t h e h o t s p o t , b u t s u r r o u n d i n g 600 " F ) by v a r y i n g t h e f u e l / a i r m i x t u r e r a t i o .

The t e s t l j n e r c o o l i n g a i r f l o w r a t e i s v a r i a b l e from about TC's i n d i c a t e d t h e maximum temperature was a t l e a s t 4.0 t o 7.5 l b / s e c a t 35 p s i g . 937 " C (1720 'F) and c o u l d have been o v e r 976 " C Both t h e c o o l i n g - a i r t e m p e r a t u r e and flow r a t e can be v a r i e d to o b t a i n t h e (1890 OF).

d e s i r e d c y c l i c temperatures on t h e t e s t l i n e r . A composite photograph o f t h e l i n e r a f t e r 1782 c y c l e s i s shown i n F i g . 28. T h i s shows t h a t most o f The a n n u l a r r i g has s i x 5 - i n . d i a m e t e r q u a r t z window v i e w p o r t s , t h r e e of which a r e spaced a t 120" t h e d i s t o r t i o n o c c u r r e d i n l o u v e r s 4 t o 7, p a r t i c u l a r l y i n t h e b o t t o m (180") and l e f t (270") views. The t o p a p a r t and a r e used t o v i e w t h e m i d d l e s e c t i o n o f t h e t e s t l i n e r . ( 0 " ) and r i g h t ( 9 0 " ) views show l e s s d i s t o r t i o n .

The o t h e r t h r e e , a l s o spaced a t 120" a p a r t , a r e used t o v i e w t h e upstream p o r t i o n o f t h e The t e s t program was t e r m i n a t e d a f t e r 1782 c y c l e s l i n e r and i t s attachment p i e c e . because t h e d i s t o r t i o n o f t h e l o u v e r s became severe These windows a r e r o t a t e d 45" from t h e l i n e r windows. enough to c o n t a c t t h e frame o f one o f t h e q u a r t z lamp The q u a r t z win- dows a r e a i r and water c o o l e d . Through these windows banks. Measurements o f t h e c r a c k from t h e i n i t i a l t e l e v i s i o n , i n f r a r e d , and h i g h r e s o l u t i o n cameras a r e o b s e r v a t i o n a t 1600 to 1728 c y c l e s i n d i c a t e d 2 p e r c e n t i n c r e a s e i n l e n g t h .

used t o m o n i t o r l i n e r c o n d i t i o n , temperature, and d e f o r m a t i o n , r e s p e c t i v e l y . The d i s t o r t i o n o f t h e l o u v e r s i s t y p i c a l o f l i n - A m i c r o p r o c e s s o r w i t h a d u a l - l o o p programmable e r s r u n i n s e r v i c e . The d i s t o r t i o n shows some symme- c o n t r o l l e r i s used to c o n t r o l t h e power to t h e lamps. t r y t o t h e h e a t p a t t e r n o f t h e lamps i n t h a t t h e peaks A s p e c i f i e d power-time h i s t o r y i s programmed i n t o t h e o f d i s t o r t i o n a r e a t t h e l o n g i t u d i n a l c e n t e r o f a lamp t h e r e t e n t i o n l o o p . For t h e c o n v e n t i o n a l l i n e r , t h e bank where t h e maximum h e a t f l u x o c c u r r e d . It should c r i t i c a l l o c a t i o n was a t t h e seam weld.

be n o t e d t h a t a d i s t o r t i o n peak was n o t formed a t Based on t h e s t r e s s - s t r a i n and t e m p e r a t u r e a t t h e e v e r y bank o f lamps. c r i t i c a l l o c a t i o n s , c y c l i c l i f e of t h e two l i n e r s was S i m i l a r l y , a l a r g e q u a l i t y d a t a base on t h e assessed. The r e s u l t s a r e summarized and compared i n advanced combustor l i n e r i s b e i n g o b t a i n e d . T h i s Table 11. The e s t i m a t e d l i f e of t h e c o n v e n t i o n a l l i n e r , c o n s i s t i n g o f small panels and an o u t e r s u p p o r t l i n e r (400 t o 1000 c y c l e s ) i s based on l i m i t e d c y c l i c s h e l l t o which t h e panels a r e a t t a c h e d , i s i n s t r u - l i f e d a t a . Tests showed l i n e r c r a c k i n g a t t h e seam mented w i t h 125 thermocouples. 73 on t h e h o t s i d e o f weld a f t e r 1500 c y c l e s . The advanced l i n e r w i l l have t h e p a n e l s and 52 on t h e s u p p o r t s h e l l . A g r i d system a much l o n g e r l i f e than t h e c o n v e n t i o n a l l i n e r because o f l i n e s o f t e m p e r a t u r e - s e n s i t i v e p a i n t s was a p p l i e d i t has a lower average temperature ( a b o u t 215 "C t o o v e r h a l f o f t h e panels i n t h e l i n e r t o i n c r e a s e (440 O F ) ) and n o s t r u c t u r a l c o n s t r a i n t i n t h e circum- t h e a r e a i n which we c o u l d observe t e m p e r a t u r e changes. f e r e n t i a l direction. A f t e r 1500 c y c l e s t h e advanced An i n f r a r e d camera system i s b e i n g used t o o b t a i n t e m - l i n e r shows l i t t l e d i s t o r t i o n and n o c r a c k i n g . The s h e l l o f t h e p e r a t u r e maps o f a p o r t i o n o f t h e o u t e r p r e d i c t e d l i f e i s g r e a t e r t h a n l o 6 c y c l e s . These l i n e r t h r o u g h a q u a r t z v i e w i n g window. Over t h e same comparisons show t h e r e i s good agreement between p r e - h i g h - r e s o l u t i o n photographs o f t h e o u t e r f i e l d o f view, d i c t e d l i f e and measured l i f e .

s h e l l a r e a l s o b e i n g taken t o d e t e r m i n e t h e t o t a l s t r a i n d u r i n g c y c l i n g .

i s r e p r e s e n t a t i v e o f t h e d a t a o b t a i n e d F i g u r e 29 CONCLUSIONS on t h e advanced l i n e r . I t i s an i s o m e t r i c p l o t o f t h e thermocouple temperature measurements of t h e h o t The broad scope of s t r u c t u r a l a n a l y s i s a c t i v i t i e s s i d e o f t h e l i n e r panels ( w h i c h shows t h e c y l i n d r i c a l c a r r i e d o u t under t h e HOST p r o j e c t , by t h e combined e f f o r t s of i n d u s t r y , government and u n i v e r s i t i e s has l i n e r as i f i t w e r e c u t upon and f l a t t e n e d o u t ) and r e s u l t e d i n numerous s i g n i f i c a n t accomplishments and, shows a maximum temperature o f 760 "C (1400 O F ) a t t h e maximum q u a r t z lamp power ( c r u i s e c o n d i t i o n ) . A s i m i - i n some cases, m a j o r b r e a k t h r o u g h s i n t h e n o n l i n e a r t h r e e - d i m e n s i o n a l s t r u c t u r a l analyses o f t u r b i n e l a r p l o t o f t h e o u t e r s h e l l shows t h e maximum tempera- to be about 316 " C (600 O F ) . These temperatures t u r e engine h o t s e c t i o n components. The major accomplish- were o b t a i n e d for a h e a t f l u x e q u i v a l e n t t o t h a t ments i n t h e t h r e e areas o f t e c h n o l o g y addressed syn- a p p l i e d to t h e c o n v e n t i o n a l l i n e r . T r a n s i e n t d a t a a r e e r g i s t i c a l l y , namely, i n e l a s t i c c o n s t i t u t i v e model development, n o n l i n e a r three-dimensional s t r u c t u r a l a l s o b e i n g o b t a i n e d . The thermal p a i n t d i d n o t i n d i - c a t e a maximum temperature o f more t h a n about 649 " C a n a l y s i s methods and code development, and experimen- t a t i o n t o c a l i b r a t e and v a l i d a t e t h e codes a r e summa- (1200 OF). The i n f r a r e d d a t a and t h e h i g h - r e s o l u t i o n photographs a r e b e i n g reduced and a n a l y z e d . r i z e d below: A f t e r 1500 thermal c y c l e s t h e advanced l i n e r i s o p e r a t i n g a t much lower temperatures t h a n t h e conven- ( 1 ) New t y p e s o f m u l t i a x i a l v i s c o p l a s t i c c o n s t i - t u t i v e models for h i g h - t e m p e r a t u r e i s o t r o p i c and a n i - t i o n a l l i n e r ( a b o u t 205 " C (400 O F ) l o w e r ) f o r t h e same s o t r o p i c ( s i n g l e c r y s t a l ) s u p e r a l l o y s , and metal h e a t f l u x . A t t h e l o w e r t e m p e r a t u r e and low thermal m a t r i x composites have been developed, c a l i b r a t e d , and g r a d i e n t s , l i t t l e d i s t o r t i o n t o t h e p a n e l s has been observed. Based on t h e t e s t r e s u l t s and a n a l y s e s , t h e v a l i d a t e d .

o p e r a t i n g c o n d i t i o n s a r e n o t severe enough t o d i s t o r t ( 2 ) New and improved n o n l i n e a r s t r u c t u r a l a n a l y - o r damage t h e advanced l i n e r .

s i s methods and codes, in which t h e v i s c o p l a s t i c con- s t i t u t i v e models were i n c o r p o r a t e d have been developed T h e r m a l / S t r u c t u r a l / L i f e Analyses o f t h e T e s t L i n e r s and, t o some e x t e n t , v a l i d a t e d .

The l i n e r s u r f a c e temDerarure measurements ( 3 ) E x t e n s i v e q u a l i t y databases, i n c l u d i n g u n i a x - o b t a i n e d from t h e thermocouples and t h e i n f r a r e d t h e r - i a l and m u l t i a x i a l thermomechanical d a t a , were gener- m o v i s i o n system were used t o o b t a i n t h e f i l m c o e f f i - a t e d f o r R e d N4, RenC 80, H a s t e l l o y - X , MAR M247, c i e n t s on t h e c o o l and h o t surfaces. Based on these B-l900+Hf. PWA1480 and Haynes 188 m a t e r i a l s f o r t h e c o e f f i c i e n t s , a h e a t t r a n s f e r a n a l y s i s o f each l i n e r purpose o f c a l i b r a t i n g and v a l i d a t i n g t h e c o n s t i t u t i v e was p e r f o r m e d u s i n g MARC, a g e n e r a l purpose n o n l i n e a r models.

f i n i t e - e l e m e n t h e a t - t r a n s f e r and s t r u c t u r a l - a n a l y s i s program.

( 4 ) E x t e n s i v e q u a l i t y databases have been gener- Eight-node t h r e e - d i m e n s i o n a l s o l i d elements were a t e d f o r c o n v e n t i o n a l and advanced combustor l i n e r used to c o n s t r u c t t h e l i n e r h e a t t r a n s f e r models.

segments and compared w i t h d e t a i l e d t h e r m a l / s t r u c t u r a l The c o n v e n t i o n a l l i n e r model had 546 elements and a n a l y s e s o f these l i n e r s u s i n g many o f t h e a n a l y t i c a l 1274 nodes, and t h e advanced l i n e r model had 536 e l e - t o o l s developed under HOST.

ments and 1117 nodes. Comparisons between p r e d i c t e d and measured t r a n s i e n t temperatures showed good ( 5 ) Advanced i n s t r u m e n z a t i o n t o measure tempera- agreement.

t u r e , d i s p l a c e m e n t and s t r a i n have been e v a l u a t e d .

The t e m p e r a t u r e (or thermal l o a d s ) a r e i n p u t t o t h e s t r u c t u r a l a n a l y s i s program. The MARC program was ( 6 ) H i g h temperature l a b o r a t o r i e s and f a c i l i t i e s used t o p e r f o r m t h e s t r u c t u r a l a n a l y s i s . The s t r e s s a t u n i v e r s i t i e s , o t h e r governmental agencies, and t o t h e h e a t t r a n s f e r models.

models were i d e n t i c a l The Walker and Bodner v i s c o p l a s t i c models, which i n d u s t r y have been m o d i f i e d and upgraded, and a t NASA Lewis, a u n i q u e h i g h - t e m p e r a t u r e f a t i g u e and s t r u c - were d e s c r i b e d e a r l i e r , were used i n t h e s t r u c t u r a l R e p r e s e n t a t i v e r e s u l t s a r e t h e h y s t e r e s i s t u r e s r e s e a r c h l a b o r a t o r y has been implemented.

a n a l y s i s .

loops shown i n F i g . 30 f o r t h r e e l o c a t i o n s on t h e con- ( 7 ) A t NASA Lewis, a h i g h - t e m p e r a t u r e s t r u c t u r a l v e n t i o n a l l i n e r . S i m i l a r l y , F i g . 31 i s r e p r e s e n t a t i v e f o r t e s t i n g component response r e s e a r c h f a c i l i t y o f a s t r e s s p l o t o f a s y m m e t r i c a l l y heated p a n e l .

of t h e 1 arge d i a m e t e r combustor 1 i n e r segments has been Based on t h e n o n l i n e a r s t r u c t u r a l analyses implemented.

two l i n e r s , i t was determined t h a t t h e c r i t i c a l s t r e s s - s t r a i n l o c a t i o n i n t h e advanced l i n e r was a t McKnight, R.L., Chen, P.C., Dame, L.T., Holt, R . V . , While t h e s t r u c t u r a l a n a l y s i s c a p a b i l i t i e s and Hugny. H . , H a r t l e , M . , G e l l i n , S . , A l l e n , D.H.. and accomplishments d e s c r i b e d i n t h i s paper a r e a good H a i s l e r . W.E.. 1986, "On 30 I n e l a s t i c A n a l y s i s b e g i n n i n g , t h e r e i s much room f o r improvement. I t i s Methods for Hot S e c t i o n Components," T u r b i n e Engine expected t h a t these c a p a b i l i t i e s and f u t u r e improve- Hot S e c t i o n Technology 1986, NASA CP-2444.

ments w i l l grow r a p i d l y i n t h e i r e n g i n e e r i n g a p p l i c a - pp. 257-268.

t i o n s and have a m a j o r i m p a c t and p a y o f f i n t h e a n a l y s i s and d e s i g n o f t h e n e x t g e n e r a t i o n a e r o n a u t i c Nakazawa, S . , 1987, "On 3D I n e l a s t i c A n a l y s i s Methods and aerospace p r o p u l s i o n systems.

for Hot S e c t i o n Components, V o l . 1 - S p e c i a l F i n i t e Element Models," NASA CR-179494.

REFERENCES W i l s o n , R.B. and B a n e r j e e , P.K., 1986, "On 3D I n e l a s t i c A n a l y s i s Methods f o r Hot S e c t i o n Componeits, Chan, K . S . , Lindholm, U.S., Bodner, S.R., H i l l , J.T.,

Vol. 2 - Advance S p e c i a l F u n c t i o n Models." NASA

Weber, R . M . , and Meyer, T . G . , 1986, NASA CR-17922.

CR-179517.

Walker, K . P . , 1981, "Research and Development Program for Non-Linear S t r u c t u r a l M o d e l i n g W i t h Advanced Time- B a t t i s t e , R.L. and B a l l , S.J., 1986, " D e t e r m i n a t i o n Temperature Dependent Cons ti t u ti ve Re 1 a t i o n s h i ps , '' o f Surfaces o f Constant I n e l a s t i c S t r a i n Rate a t NASA CR-165533. E l e v a t e d Temperature," T u r b i n e Engine Hot S e c t i o n Technology 1986, NASA CP-2444, pp. 307-325.

Bodner, S . R . and Partom, Y . , 1975, " C o n s t i t u t i v e B a r t o l o t t a . P . A . and McGaw, M . A . , 1987, " A High Equations f o r E l a s t i c - V i s c o p l a s t i c S t r a i n - H a r d e n i n g Temperature F a t i g u e and S t r u c t u r e s T e s t i n g F a c i l i t y , " M a t e r i a l s , " J o u r n a l o f A p p l i e d Mechanics, Vol. 42, NASA TM-100151.

NO. 2 , pp. 385-389.

B a r t o l o t t a , P . A . , 1985. "Thermomechanical C y c l i c Ramaswamy, V . G . , 1986, " A C o n s t i t u t i v e Model for t h e Hardening B e h a v i o r o f H a s t e l l o y - X , " NASA CR-174999.

I n e l a s t i c M u l t i a x i a l C y c l i c Response o f a N i c k e l Base Superal l o y RENE 80," NASA CR-3998.

E l l i s , J.R., B a r t o l o t t a , P . A . , A l l e n , G.P., and Robinson, D . N . . 1986. "Thermomechanical C h a r a c t e r - Robinson, D.N., 1984, " C o n s t i t u t i v e R e l a t i o n s h i p s for i z a t i o n o f H a s t e l l o y - X Under U n i a x i a l C y c l i c L o a d i n g , " A n i s o t r o p i c High-Temperature A l l o y s , " Nuclear T u r b i n e Engine Hot S e c t i o n Technology 1986, NASA E n g i n e e r i n g and Design, Vol. 83, No. 3, pp. 389-396.

CP-2444, pp. 293-305.

K . P . , and Jordan, E . H . , 1987, " C o n s t i t u t i v e Walker, B a r t o l o t t a , P . A . , 1987, "Use o f I n e l a s t i c S t r a i n as a M o d e l l i n g o f S i n g l e C r y s t a l and D i r e c t i o n a l l y Basis f o r A n a l y z i n g Thermomechanical T e s t Data," S o l i d i f i e d S u p e r a l l o y s , " T u r b i n e Engine Hot S e c t i o n T u r b i n e Engine Hot S e c t i o n Technology 1987, NASA Technology 1987, NASA CP-2493, pp. 299-301.

CP-2493, pp. 303-31 5 .

Dame, L . T . , and S t o u f f e r , D.C., 1986, " A n i s o t r o p i c C o n s t i t u t i v e Model f o r N i c k e l Base S i n g l e C r y s t a l E l l i s , J.R., B a r t o l o t t a , P . A . , and M l a d s i , S.W., 1987, " P r e l i m i n a r y Study o f Creep Thresholds and Thermo- A l l o y s : Development and F i n i t e Element mechanical Response i n Haynes 188 a t Temperatures i n I m p l e m e n t a t i o n , " NASA CR-175015.

t h e Range 649 t o 871 "C," T u r b i n e Engine H o t S e c t i o n S.F., and E l l i s , J.R., 1986, Technology 1987, NASA CP-2493, pp. 31 7-334.

Robinson, D.N., D u f f y .

" A V i s c o p l a s t i c C o n s t i t u t i v e Theory f o r M e t a l M a t r i x Thompson, R.L. and Tong, M . T . , 1986, " U n i f i e d Con- Composites a t H i g h Temperature," NASA CR-179530.

s t i t u t i v e M a t e r i a l s Model Development and E v a l u a t i o n Maffeo, R . , 1984, "Burner L i n e r T h e r m a l - S t r u c t u r a l f o r High-Temperature S t r u c t u r a l A n a l y s i s A p p l i c a - t i o n s , " 1 5 t h Congress o f t h e I n t e r n a t i o n a l C o u n c i l Load M o d e l i n g , " NASA CR-174892.

o f t h e A e r o n a u t i c a l Sciences, Vol. 2, A I A A . New York, pp. 1505a-1505s.

McKnight, R.L., 1985, "Component-Specific Modeling," NASA CR-174925.

TABLE I. - HOST STRUCTURAL ANALYSIS PROGRAMS

NAS3-23925, Southwest Research I n s t i t u t e (U.S. L i n d h o l m ) , C o n s t i t u t i v e M o d e l i n g for I s o t r o p i c M a t e r i a l s .

NAS3-23927, General E l e c t r i c (V.G. Ramaswamy), C o n s t i t u t i v e M o d e l i n g f o r I s o t r o p i c M a t e r i a l s .

NAS3-379, U n i v e r s i t y o f Akron (D.N. Robinson), M u l t i a x i a l T h e o r i e s of V i s c o p l a s t i c f o r I s o t r o p i c and A n i s o t r o p i c M a t e r i a l s .

NAG3-512, U n i v e r s i t y o f C o n n e c t i c u t ( E . H . J o r d a n ) . C o n s t i t u t i v e M o d e l i n g o f S i n g l e C r y s t a l and D i r e c t i o n a l l y S o l i d i f i e d S u p e r a l l o y s .

NAG3-511, U n i v e r s i t y o f C i n c i n n a t i ( D . C . S t o u f f e r ) , A n i s o t r o p i c C o n s t i t u t i v e M o d e l i n g f o r Nickel-Base S i n g l e C r y s t a l S u p e r a l l o y Re& N4.

NAS3-23272, General E l e c t r i c ( R . Maffeo), Burner L i n e r T h e r r n a l / S t r u c t u r a l Load M o d e l i n g .

NAS3-23687, General E l e c t r i c (R.L. McKnight), Component-Specific M o d e l i n g .

NAS3-23698, General E l e c t r i c (R.L. M c K n i g h t ) , Three-Dimensional I n e l a s t i c A n a l y s i s Methods f o r Hot S e c t i o n Components I.

NAS3-23697, P r a t t and Whitney A i r c r a f t (E.S. Todd), Three-Dimensional I n e l a s t i c A n a l y s i s Methods f o r Hot S e c t i o n Components 11.

IAN 40-1447-84 and DE-AC05-840R 21400, Oak Ridge N a t i o n a l L a b o r a t o r y (J.R. Corum), D e t e r m i n a t i o n o f S u r f a c e o f C o n s t a n t I n e l a s t i c S t r a i n Rate a t E l e v a t e d Temperature.

NASA Lewis Research C e n t e r (J.R. E l l i s and P.E. Moorhead), High-Temperature F a t i g u e and S t r u c t u r e s L a b o r a t o r y l S t r u c t u r a l Component Response F a c i l i t y .

TABLE 11. - CREEP

THRESOLDS DETERMINED FOR H A Y N E S 188 A T TEMPERATURES I N THE RANGE 649 TO 871 "C Temper- Creep

1 aty;e. 1 thr;:pld,a I

~ - - - ~ - -

&\act\& . F ,:.r& 4 ; s

c x POOR C h i A L r n

TABLE 111. - SUMMARY OF STRUCTURAL-LIFE ANLAYSES OF COMBUSTOR LINERS A T A CRITICAL LOCATION S t r a i n range, Mean s t r e s s , P r e d i c t e d l i f e , A n a l y t i c a l Temperature c y c l e s range, w p s i met hod "- Mechanical I n e l a s t i c U n i f i e d ( W a l k e r ) 950 t o 1630 5870 31 50 -35 000 400 t o 1000

1 U n i f i e d (Bodner) 1 950 to 1630 I 5800 1 2700 1 -28 000 I 400 t o 1000 I

( b ) Segmented l i n e r A n a l y t i c a l Temperature S t r a i n range, Mean s t r e s s , P r e d i c t e d l i f e , met hod range, P P s i cyc 1 es "F Mechanical I n e l a s t i c U n i f i e d ( W a l k e r ) 755 t o 1180 81 0 10-1 10 000 ,106 U n i f i e d (Bodner) 7 5 5 t o 1180 820 10-1 15 000 > l o 6 HOT SECTION COMPONENTS

\ /

HEATEDKOOLED TURBINE TURBINE BLADE BLADE - - COMBUSTOR LINER COMBUSTOR LINER MISSION LOADS

/ \

\ / LABORATORY SIMULATION COMPONENT MODELING c m p " ~ STRESSES/STRAINS TEMPERATURES HEATEDKOOLED

/

= \

DEFORMATION/DAMAGE ANALYSIS-LIFE PREDICTION

/

\

MATERIALS TESTING

/

\

COMPUTATIONAL METHODS AND CODE DEVELOPMENT FIGURE 1, - NONLINEAR STRUCTURAL ANALYSIS TECHNOLOGIES AND ACTIVITIES UNDER HOST ISOTHERML DATA R - 0 0 0 - 1 0 -m NON ISOTHERMAL DATA

z

In fn W a I - fn

- BODNER-PARTON

-1000 -0.4 -0.2 0 .2 .4 .6 . 2 .4 .6 .8 MECHANICAL STRAIN. PERCENT AE/2, PERCENT FIGURE 2. - CONTROLLED STRAIN CYCLING WITH TEMPERATURE FIGURE 3 . - C W A R I S O N OF ISOTHERMAL AND NON- CHANGE FROM 538 OC TO 982 OC.

OF B1900+H~ AT 760 OC.

ISOTHERMAL CYCLIC DATA TEMPERATURE , OC (2) 695 (3) 735 LOCATION 'A" (4) 775 NEAR EXTERNAL ( 5 ) 815

SURFACE - - - -

CREEP-PLASTICITY RODELS

---

WALKER RODEL

i

--- BODNER-PARTOM M D E L

"4

v) fn W CT I- o * W + U W LL SHEAR STRESS. WA U W FIGURE 5. - RENE'80 RESPONSE TO 9 0 ' OUT-OF- -200 PHASE TENSION/TORSION CYCLIC LOADING.

-4000 * -3000 -2000 -1000 0 -400

EFFECTIVE MICROSTRAIN - AIRFOIL CALCULATIONS AT LOCATION "A" USING THE FIGURE 4.

M R C F I N I T E ELEMENT ANALYSIS CODE.

; 649 OCT I / I

, ' - E X P E R I E N T

G

MODEL W $ 3 0 a W I- v) oc c ln -80 -800 -.04 - .02 0 .02 .04 E C H A N I C A L STRAIN x 10-1 FIGURE 6. - RENE'80 1% RESPONSE (649-1093 OC OUT-OF- PHASE ) .

-160 -.4 -.2 0 . 2 .4 STRAIN. PERCENT - SATURATED HYSTERESIS LOOPS FOR FIGURE 7.

SHOWN A € = 0.6 PERCENT AND € = .001/n.

rs UNIAXIAL RESPONSE AND SHEAR RESPONSES

FOR SEVERAL VALUES O F C.

DRUCKER- .08

-

.12 I- W U I- K W L E l U a AX I AL W 0 f,

d -04

E .06

-5

d

-I 60 OOO (110) A A A w In P ( 1 1 1 ) L a 2 40000 ~

- Q

C c ln 1 KSI = 6.9 WA 0 20 40 60 80 100 TIMEE. HR EXPERIPENTAL DATA

FIGURE 8. - CREEP RESPONSE I N UNIAXIAL TENSION AND SHEAR FOR

TEST RATE: I.OE-~/SEC SEVERAL VALUES OF C.

0 ,005 .010 .015 .020 A X I A L STRAIN. IN./IN.

FIGURE 9. - RENE N4 PREDICTED TENSILE RESPONSE AND EXPERIMENTAL DATA FOR SPECIMEN ORIENTATIONS OF [1001, [1101. AND [ 1 1 1 1 AT 982 OC (1800 OF).

AXIAL: <100> 40 OOO ' FIBER OR I ENTAT I ON - ANGLE.

- 6 0 v) Y at 0 .

1 KSI = 6.9 P A -40 OOO .

EXPERIKNTAL DATA TE: j . N - g / S E C

t , 30

-80 OOO c -0.010 -0.005 0 .005 . 0 1 0 \ d AXIAL STRAIN. IN./IN.

1 9 0 1

I I I I

FIGURE 10. - RENE N4 PREDICTED CYCLIC RESPONSE AND 0 200 400 600 800 lo00 EXPERIENTAL DATA FOR S P E C I E N ORIENTATION OF C1001 T I E E . HR AT 982 OC ( 1 8 0 0 %).

FIGURE 11. - RELAXATION CURVES FOR DIFFERENT FIBER

OR I ENTAT I ON ANGLES.

1 0 0 r-- I

-

v) X v) v) W E I - v)

-100 r I I I I I I

-2.0 -1.2 - . 4 .4 1 . 2 2x10-3 STRAIN

FIGURE 1 2 . - HYSTERESIS LOOPS FOR DIFFERENT FIBER

ORIENTATION ANGLES: STRAIN RATE = 0 . 0 0 1 / ~ 1 ~ .

STRESS CODE HEAT TRANSFER (HT) C O N CD-87-29219 FIGURE 13. - SCHERATIC FOR THREE-DIENSIQAL TRANCITS C W U T E R P R O G M .

CMBUSTOR LINER PARMETER LIST CODE “E DEFAULT CODE N A E DEFAULT X = COORDINATE 1 Y = COORDINATE x1 0.0 0.0 y1 o1 0.0 3 0 = ANGLE MRT. x - AXIS 10.5 L1 5 L = LENGTH L2 2.0 0.5 L3 L4 6.0 7 T = THICKNESS 0.8 L5 9 0 = ANGLE OF ROTATION L6 1.0 10 L7 2.0 R = RADIUS OF CURVATURE T i 0.5 12 T2 0.7 13 ( N ) = PARAETER CODE NUWBER T3 0.5 14 T4 0.65 T5 0.5 16 01 90.0 02 90.0 18 R1 1.0 R2 1.0 20 R3 0.75 R 4 1.5 22 R5 1.5 R6 1.5 I I +-L7 (10-

I I

L L4 (7) -

I I

FIGURE 14. - COMBUSTOR LINER PARAETERS.

MAIN EXECUTIVE 1 I N . = 2.54 CM TDLR 0 2000 40006000 8 0 0 0 1 0 0 0 0 1 4 0 0 0 1 8 0 0 0 ELAPSED FLIGHT TIME. SEC C W O N E N T RECIPE FIGURE 16. - RADIAL DISPLACEMENT O F LEADING EDGE T I P , STAT1C.

BANDUIDTH OPTIflIZER

I

DECK GENERATION

I

F I N I T E ELEMENT M O D E L , F I N I T E ELEMENT MODEL STRUCTURAL CODE F I N E RESH COARSE MESH

Q

t

DATA BASE ROUTINES RERESH/MESH REFINE

I

POSTPROCESSING

FIGURE 15. - SYSTEfl F L O W CHART

BOUNDARY ELEHENT MODEL FOR C O W .

MIXED VARIATION L - LINEAR Q - QUADRATIC

&/ L L

FIGURE 17. - MESHES USED I N BENCHMARK NOTCH ANALYSIS.

BEST3D-5% LOAD STEP BEST3D-20% LOAD STEP ~ ? 4OOo 0 EASURED DATA

I I I I I I I I

-4 0 4 8 NOTCH STRAIN - fllCROSTRAlN € 3 FIGURE 18. - CYCLIC BEHAVIOR AT ROOT OF S P E C I E N NOTCH.

O t I

-50 - 7 5 k 0 -100 -125 ln I n -100 -50 0 50 100 150 -100 -50 0 50 100 150 -150 -100 -50 0 50 100 150 : 0 W AXIAL STRESS. KSI

c

z ( A ) I N I T I A L V I R G I N S P E C I E N . (B) AT POINT 2. AFTER 0.84% TORSION- (C) AT P O l N T 3 . UPON RETURN TO ZERO

z W AL PRELOAD. LOAD AND STRAIN AFTER I N I T I A L PRE-

I LOAD.

1 KSI = 6.9 P A , r S H E A R STRESS, T O C 0 0

o c

L Q I

-75 8) 0 - 5 I

I @ O I -100 0 SHEAR STRAIN. I 3 0 r/2. PERCENT _1 -125

9 1 1

-200 -150 -100 -50 0 50 100 150 -200-150-100-50 0 50 100 150200 (D) AT POINT 4, AFTER -0.5% TORSION (E) AT POINT 5 . AFTER RETURN TO ZERO PRELOAD. LOAD AND STRAIN.

FIGURE 19. - EASURED 650 OC SURFACES OF CONSTANT INELASTIC STRAIN RATE FOR REFERENCE SClSRs TEST P R W R M .

COMMERCIALLY AVAILABLE B I A X I A L EXTENSOMETER U N I A X I A L TEST SYSTEM U N I A X I A L LONGITUDINAL EXTENSOMETER I N TEST SETUP B I A X I A L MATERIAL TEST SYSTEM FIGURE 21. - B I A X I A L MATERIAL TEST SYSTEM.

FIGURE 20. - U N I A X I A L TEST SYSTEM.

MATERIAL. HASTELLOY-X CYCLE 10 -200 "200 TO 400 OC -400 l : : -600 -4Ooo -2000 0 2000 4OOo-2000 -1000 0 1000 2000 INELASTIC STRAIN, p € KCHANICAL STRAIN, UE CYCLE 5000 FIGURE 2 2 . - COMPARISON OF MATERIAL RESPONSE DETERNINED UNDER ISOTHERMAL AND THERMO- ECHANICAL CYCLIC LOADING.

ORBGlMAB PAGE B S

OF POeR QUALITY

-

CYCLE n r - I 0 2 a

- A 3

0 4 0 5

-

-

0 0 0 A . v - 0 5 1 K S I = 6.9 MPA

0 ' e'

0 e

I

L 100 200 300 400 500 E C H A N I C A L STRAIM, CIE

FIGURE 23. - CREEP RATCHETTING RESULTING FROM THERRORECHANICAL CYCLING

6.17 KSI MEAN STRESS.

FOR FIGURE 24. - STRUCTURAL COMPONENT RESPONSE R I G .

ADVANCED (SEGMENTED) -1NG.

25. - CONVENTIONAL AND SEGMENTED COMBUSTOR LINERS INSTRUMENTED FOR TESl FIGURE

ORIGINAL PAGE I S

OF POOR QUALITY

ORIGINAL PAGE I S

OF POOR QUALITY

THERMOCOUPLE DATA COOLANT FLOW RATE, 5.5/SEC: COOLANT FLOW TEMPERATURE, 315 OC (600 OF) lo00

1800 r SEAN HELD

I r THERMAL CYCLE

-F

V W W

$ 600

lo00

"t 400

600 '

0 20 40 60 80 100 120 140 T I E Z . SEC T I E , SEC FIGURE 27. - POWER HISTORY FOR THERMAL CYCLE.

FIGURE 26. - CYCLIC SURFACE LINER TEWERATURES AT THREE LOCATIONS ON LOUVER 5.

28. - COMPOSITE PHOTOGRAPH OF HOT S I D E CONVENTIONAL L I N E R D I S T O R T I O N AFTER 1782 THERMAL CYCLES.

FIGURE 8 1 L L W CT a p : W l- a CL

; 6 0 0 ! 300

W

! 3

+ C

- 14

DEG IN.

FIGURE 29. - I S O r r T R I C PLOT OF TEPPERATURE ON I N S I D E OF SEGFTNTED COWBUSTOR L I N E R .

V I S C O P L A S T I C CONSTITUTIVE MODEL: WALKER T M O R Y (3RD CYCLE) STRESS, LOUVER 5 PSI 6Ox1O3 14 375

n

r

12 926 KNUCKLE 1 1 476

40 i

10 027

I SEAM M L D

I

a 578

u l P 7 129 v, v) W 5 679 a I- v) 4 230 2 781 1 332

/

8 -20 2~~

-118 1 KSI = 6.9 w A ETENTION -1 567 LOW -3 016 -4 465 -5 915 1 KSI = 6.9 W A -7 3 6 4

FIGURE 31. - ADVANCED COMBUSTOR L I N E R STRESS D I S T R I B U T I O N ON S Y M E T R I

ICAL PANEL AT AN 8 3 PERCENT POWER LEVEL ( X - D I R E C T I O N ) .

STRUCTURAL ANALYSIS APPLICATIONS R. L. McKnight General Electric AEBG Cincinnati, Ohio For b o t h o f t h e s e t y p e s o f a n a l y s e s , some p o r t i o n ABSTRACT of t h e a i r f r a m e - e n g i n e system i s m a t h e m a t i c a l l y simu- l a t e d and a h i s t o r y o f t h e o p e r a t i n g environment and The programs i n t h e s t r u c t u r a l a n a l y s i s a r e a o f i n t e r a c t i o n e f f e c t s o f t h e remainder o f t h e system t h e HOST program emphasized t h e g e n e r a t i o n of computer imposed as l o a d s and boundary c o n d i t i o n s . For f u n c - codes for p e r f o r m i n g t h r e e - d i m e n s i o n a l i n e l a s t i c a n a l y - t i o n a l i t y t h e simpler-maximum h i s t o r y can be imposed s i s w i t h more a c c u r a c y and l e s s manpower. T h i s paper on a l a r g e r p o r t i o n o f t h e o v e r a l l system. Since p r e s e n t s t h e a p p l i c a t i o n o f t h a t t e c h n o l o g y t o A i r c r a f t d u r a b i l i t y l r e l i a b i l i t y i s a p o i n t f u n c t i o n , s m a l l e r Gas T u r b i n e Engine (AGTE) components; combustors, t u r - p o r t i o n s o f t h e system must be r u n t h r o u g h t h e t o t a l b i n e b l a d e s , and vanes. P r e v i o u s l i m i t a t i o n s w i l l be complex h i s t o r y o f l o a d i n g . For b o t h o f these a n a l y - reviewed and t h e b r e a k t h r o u g h t e c h n o l o g y h i g h l i g h t e d .

ses, t h e l o a d i n g , environment, and i n t e r a c t i o n s a r e The synergism and s p i l l o v e r of t h e program w i l l be p r o v i d e d t o t h e a n a l y s t from o t h e r " e x p e r t " groups.

demonstrated by r e v i e w i n g a p p l i c a t i o n s t o thermal b a r - A d e f i c i e n c y common t o b o t h t y p e s o f a n a l y s e s i s r i e r c o a t i n g s a n a l y s i s and t h e SSME HPFTP t u r b i n e t h a t of e c o n o m y l p r o d u c t i v i t y as measured by t h e t o t a l b l a d e . These a p p l i c a t i o n s show t h a t t h i s t e c h n o l o g y o f t i m e , number o f man-hours, and t h e computer p e r i o d has i n c r e a s e d t h e a b i l i t y of t h e AGTE d e s i g n e r t o be r e s o u r c e s r e q u i r e d t o complete a d e s i g n a n a l y s i s . For more i n n o v a t i v e , p r o d u c t i v e , and a c c u r a t e .

f u n c t i o n a l a n a l y s e s , t h e second m a j o r d e f i c i e n c y was due t o t h e c o m b i n a t i o n o f t h e f o r m u l a t i o n models INTRODUCTION ( F i n i t e - E l e m e n t Model, F i n i t e D i f f e r e n c e Model, Bound- a r y Element Model) and t h e n u m e r i c a l a c c u r a c y o f t h e The a c t i v i t i e s o f t h e NASA T u r b i n e Engine Hot computer. These l i m i t a t i o n s a f f e c t e d t h e a b i l i t y t o S e c t i o n Technology P r o j e c t were d i r e c t e d t o w a r d f u n c - a c c u r a t e l y s i m u l a t e l a r g e systems w i t h t h e i r complex t i o n a l i t y and d u r a b i l i t y needs o f AGTE h o t s e c t i o n i n t e r a c t i o n s w i t h o u t e x c e p t i o n a l l y f i n e modeling. F o r

components - t h e combustor, t u r b i n e vanes, and t u r b i n e

t h e second m a j o r d e f i - d u r a b i l i t y l r e l i a b i l i t y a n a l y s e s , b l a d e s . The o v e r a l l approach o f t h i s program was t o c i e n c y was t h e i n a b i l i t y o f t h e c o m b i n a t i o n o f t h e assess t h e e x i s t i n g a n a l y s i s methods f o r s t r e n g t h s and f o r m u l a t i o n models, c o n s t i t u t i v e models. and t h e numer- d e f i c i e n c i e s , and t h e n t o c o n d u c t s u p p o r t i n g a n a l y t i c a l t o a c c u r a t e l y s i m u l a t e i c a l a c c u r a c y o f t h e computer and e x p e r i m e n t a l r e s e a r c h t o r e c t i f y t h o s e d e f i c i e n c i e s t h e l o c a l i n e l a s t i c m a t e r i a l b e h a v i o r . T h i s d e f i c i e n c y and, a t t h e same t i m e , i n c o r p o r a t e s t a t e - o f - t h e - a r t was p a r t i c u l a r l y e v i d e n t i n t h e h o t s e c t i o n components improvements i n t o t h e a n a l y s i s methods.

exposed t o t h e severe thermal and mechanical o p e r a t i n g S t r u c t u r a l a n a l y s i s has two m a j o r o b j e c t i v e s i n o f t h e AGTE. The l o c a l , d u r a b i l i t y l i m i t - environments t h e d e s i g n of AGTE's. The f i r s t m a j o r o b j e c t i v e i s t o i n g , areas o f t h e s e s t r u c t u r e s a r e exposed t o t i m e g e n e r a t e and v e r i f y a f u n c t i o n a l d e s i g n . The second v a r y i n g t e m p e r a t u r e d i s t r i b u t i o n which a f f e c t b o t h t h e major o b j e c t i v e i s t o q u a n t i f y t h e d u r a b i l i t y 1 m a t e r i a l p r o p e r t i e s and t h e t h e r m a l and mechanical r e l i a b i l i t y of t h e s e d e s i g n s . The f i r s t o b j e c t i v e can s t r e s s e s i n a complex t h r e e - d i m e n s i o n a l manner.

be accomplished b y a n a l y z i n g c a n d i d a t e d e s i g n s for a The HOST program s u c c e s s f u l l y accompli shed i t s

s i m p l i f i e d m i s s i o n c y c l e - t h e maximum envelope o f t h e

T h i s was g o a l s by a t t a c k i n g t h e above d e f i c i e n c i e s .

t e c h n i c a l r e q u i r e m e n t s . E v a l u a t i o n s a r e made b y com- i n which were deve- done t h r o u g h a s e r i e s o f programs

p a r i n g t h e code o u t p u t s - d i s p l a c e m e n t s , s t r e s s e s , and

l o p e d c o n s t i t u t i v e models, t h r e e - d i m e n s i o n a l i n e l a s t i c

s t r a i n s - a g a i n s t t e c h n i c a l r e q u i r e m e n t s and d e s i g n

s t r u c t u r a l a n a l y s i s codes, a t h r e e - d i m e n s i o n a l t h e r m a l p r a c t i c e s .

The second o b j e c t i v e r e q u i r e s t h a t t h e e n t i r e m i s s i o n c y c l e be a n a l y z e d and t h e code o u t p u t be combined w i t h d u r a b i 1 1 t y l r e l l a b 1 11 t y t e c h n o l o g y i n a p o s t p r o c e s s i n g o p e r a t i o n .

t r a n s f e r code, and a component s p e c i f i c n o d e l i n g sys- which perform t h i s mapping i n t h e TDLM models were t e m . :he a p p l i c a t i o n o f these advanced t o o l s was -leveloped f o r t h e s p e c i f i c engine components o f t h e almost simultaneous w i t h t h e i r development. The T o adapt these models t o a d i f f e r e n t 3 6 - 5 0 C engine.

remainder cf t h i s paper w i l l p r e s e n t s e l e c t i v e a p p l i c a - engine would r e q u i r e t h e e v a l u a t i o n of these f o r m u l a s t i o n s of these t e c h n o l o g i e s .

f o r t h e i r s i m u l a t i o n c a p a b i l i t y and r e f o r m u l a t i n g where necessary.

Combustor Design and A n a l y s i s The h e a r t o f t h e component s p e c i f i c s t r u c t u r a l Y e combustor i s one o f t h e most c h a l l e n g i n g and m o d e l i n g i s geometric modeling and mesh g e n e r a t i o n complex components o f t h e A G T E . I t s d e s i g n i n v o l v e s u s i n g t h e r e c i p e concept. A g e n e r i c geometry p a t t e r n many " e x p e r t " groups; c o n t r o l s , f u e l n o z z l e s , chemical i s determined f o r each component. A r e c i p e i s deve- combustion k i n e t i c s , h e a t t r a n s f e r , and s t r u c t u r e s .

loped f o r t h i s b a s i c geometry i n terms o f p o i n t c o o r d i - I t p r e s e n t s one o f t h e major p r o d u c t i v i t y d r a i n s i n n a t e s , l e n g t h s , t h i c k n e s s e s , a n g l e s , and r a d i i .

AGTE d e s i g n s , b o t h f o r i n i t i a l d e s i g n and for subse- 6 to 8 show t h i s process f o r a r o l l e d r i n g F i g u r e s quent t u n i n g f o r m i s s i o n v a r i a t i o n s . HOST a t t a c k e d a1 combustor. These r e c i p e parameters a r e encoded i n com- aspects of t h i s problem, e c o n o m y l p r o d u c t i v i t y as w e l l p u t e r s o f t w a r e as v a r i a b l e i n p u t parameters w i t h a s e t as accuracy, i n t h e component s p e c i f i c m o d e l i n g e f f o r t o f d e f a u l t numerical v a l u e s d e f i n e d . F i g u r e 9 d e f i n e s I n t h i s program t h e many d i v e r s e d i s c i p l i n e s which t h e r e c i p e which generates t h e combustor s t r u c t u r a l impact on a combustor l i n e r d e s i g n were i n t e g r a t e d model.

i n t o a component s p e c i f i c system u t i l i z i n g t h e HOST A snapshot of a t y p i c a l r u n o f t h e combustor model t e c h n o l o g i e s .

i s shown i n F i g . 10. A s i n d i c a t e d , t h e model c o n t a i n s The COSMO computer system c o n s i s t s o f a Thermody- o f r e c i p e parameters, o n l y changes t o a d e f a u l t s e t namic Engine Model (TDEM), a Thermomechanical Load t h i s l i s t need be g i v e n . A f t e r t h e r e c i p e parameters Model (TDLM), and Combustor S t r u c t u r a l Model. The TDEM have been s e t , o n l y f i v e parameters need be s p e c i f i e d g e n e r a t e s t h e engine i n t e r n a l flow v a r i a b l e s f o r any t o g e n e r a t e a t h r e e - d i m e n s i o n a l s e c t o r model o f a com- p o i n t i n t h e o p e r a t i n g m i s s i o n by t h e s p e c i f i c a t i o n o f to p e r f o r m a h o t s t r e a k a n a l y s i s .

b u s t o r The f i r s t t h r e e v a r i a b l e s , a l t i t u d e ( h ) , Mach number ( M ) , and parameter (shown as t h e number o f e x h a u s t n o z z l e s ) i s power l e v e l (PL) f o r t h e a l l o w e d f l i g h t map o f an r e q u i r e d to d i v i d e t h e 360" combustor i n t o t h e p r o p e r engine, as shown i n F i g . 1 . A d d i t i o n a l c o n t r o l v a r i a - number o f s e c t o r s . The n e x t parameter (shown as t h e b l e s a r e ambient temperature d e v i a t i o n s f r o m t h e stand- number o f c i r c u m f e r e n t i a l elements) i s used by t h e ana- a r d atmosphere, a i r f r a m e b l e e d a i r r e q u i r e m e n t s , and l y s t t o s p l i t up t h e c i r c u m f e r e n t l a l s e c t o r i n t o a e n g i n e d e t e r i o r a t i o n . For each i n p u t c o n d i t i o n , s p e c i - number o f s l i c e s , N S , for t h e t h r e e - d i m e n s i o n a l e l e - f i e d by h, M, and PL t h e TDEM c a l c u l a t e s gas w e i g h t ments and b i a s these s l i c e s by s p e c i f y i n g NS-1 f l o w ( w ) , t e m p e r a t u r e (t), and p r e s s u r e ( p ) f o r t h e p e r c e n t s .

For t h e p a r t i c u l a r case i n v o l v e d t h r e e e x h a u s t combustor.

The TDEM t e c h n i q u e i s shown i n F i g s . 2 t o 4 . The n o z z l e s a r e s p e c i f i e d w i t h f o u r c i r c u m f e r e n t i a l e l e - e n g i n e t o be analyzed must have i t s aerodynamic s t a - ments. These c i r c u m f e r e n t i a l elements a r e t h e n biased, t i o n s ( F i g . 2 ) d e f i n e d t h e r m o d y n a m i c a l l y by an e n g i n e s t a r t i n g a t t h e h o t s t r e a k , as 5 , 15. and 30 p e r c e n t .

cyc1.e deck (computer program) which can be r u n t o gen- T h i s leaves t h e f i n a l s l i c e t o be 50 p e r c e n t . T h i s I s e r a t e t h e i n t e r n a l f l o w v a r i a b l e s a t chosen aerodynamic a l l t h e i n f o r m a t i o n r e q u i r e d t o g e n e r a t e a t h r e e - s t a t i o n s ( F i g . 3 ) . I n COSMO t h e complete engine oper- dimensional f i n i t e - e l e m e n t model c o n s i s t i n g o f 20-noded a t i n g map ( F i g . 1 ) i s encompassed by s e l e c t i n g 148 i s o p a r a m e t r i c f i n i t e elements. I n t h i s case t h e model o p e r a t i n g p o i n t s f o r which w , t, p as w e l l as N1 c o n s i s t s of 648 elements, 3192 nodes, and has 768 e l e - and N2, t h e f a n and c o r e speeds, a r e c a l c u l a t e d for ment f a c e s w i t h p r e s s u r e l o a d i n g . F i g u r e s 1 1 and 12 a r e g r a p h i c a l d e p i c t i o n s o f t h i s t h r e e - d i m e n s i o n a l t h e s t a t i o n s p e r t i n e n t to t h e COSMO components.

From t h i s s t a t i o n d a t a an Engine Performance C y c l e model. The temperatures and p r e s s u r e s from t h e TDLM Map i s c o n s t r u c t e d . T h i s i s e s s e n t i a l l y a s e t o f a r e mapped o n t o t h i s model and t h e necessary d a t a f i l e s a r e generated f o r a n o n l i n e a r t h r e e - d i m e n s i o n a l d a t a a r r a y s which map t h e s t a t i o n s t r u c t u r a l a n a l y s i s .

N 2 ) on t o t h e e n g i n e o p e r a t i n g The subsystem which performs t h e t h r e e - d i m e n s i o n a l d a t a ( w , t. p, n1, and n o n l i n e a r f i n i t e - e l e m e n t a n a l y s i s o f t h e combustor map ( F i g . 1 ) . Given an a r b i t r a r y o p e r a t i n g p o i n t model was t h a t developed i n t h e HOST program, "Three- d e f i n e d by h, M, and PL i t i s then, i n p r i n c i p l e , p o s s i b l e t o i n t e r p o l a t e on t h e e n g i n e performance c y c l e dimensional I n e l a s t i c A n a l y s i s Methods for Hot S e c t i o n These s t a t i o n parame- S t r u c t u r e s . " T h i s s o f t w a r e p e r f o r m s i n c r e m e n t a l non- map t o d e t e r m i n e s t a t i o n d a t a .

t e r s a r e n o n l i n e a r f u n c t i o n s o f t h e i n p u t parameters l i n e a r f i n i t e - e l e m e n t a n a l y s i s o f complex t h r e e - dimensional s t r u c t u r e s under c y c l i c thermomechanical and much e f f o r t went i n t o t h e development o f t h e s e m u l t i d i m e n s i o n a l i n t e r p o l a t i o n t e c h n i q u e s . l o a d i n g w i t h temperature dependent m a t e r i a l p r o p e r t i e s The f u n c t i o n i n g o f t h e TDEM i s shown i n F i g . 4 . and m a t e r i a l response b e h a v i o r . The n o n l i n e a r a n a l y s i s Given an e n g i n e m i s s i o n . as shown s c h e m a t i c a l l y i n c o n s i d e r s b o t h t i m e independent and t i m e dependent i t can be d e f i n e d by v a l u e s o f t h e i n p u t v a r i a - F i g . 5, m a t e r i a l b e h a v i o r . Among t h e c o n s t i t u t i v e models b l e s h, M, and PL a t s e l e c t e d t i m e s t h r o u g h t h e m i s - a v a i l a b l e a r e a s i m p l i f i e d model, a c l a s s i c a l model.

s i o n . u s i n g these i n p u t v a r i a b l e s and t h e Engine and a u n i f l e d model. A m a j o r advance i n t h e a b i l i t y t o Performance C y c l e Map t h e i n t e r p o l a t i o n program c a l c u - p e r f o r m t i m e dependent analyses i s t h e dynamic t i m e i n c r e m e n t i n g s t r a t e g y i n c o r p o r a t e d i n t h i s s o f t w a r e .

l a t e s e n g i n e s t a t i o n parameters t h r o u g h o u t t h e m i s s i o n These a r e t h e n used t o d e f i n e t h e s t a t i o n The COSMO system c o n s i s t s of an e x e c u t i v e module ( F i g . 4 ) .

which c o n t r o l s t h e TDEM, TDLM, t h e g e o m e t r i c modeler, m i s s i o n p r o f i l e s o f w , t, p. N 1 , and N2 as f u n c t i o n s o f t i m e a t each aerodynamic s t a t i o n . These s t a t i o n t h e s t r u c t u r a l a n a l y s i s code, t h e f i l e s t r u c t u r e / d a t a m i s s i o n p r o f i l e s t h e n become t h e i n p u t t o t h e TDLM. base, and c e r t a i n a n c i l l a r y modules. These a n c i l l a r y modules c o n s i s t o f a bandwidth o p t i m i z e r module, a deck The TDLM i s t h e computer program which works w i t h g e n e r a t i o n module, a remeshing/mesh r e f i n e m e n t module, t h e o u t p u t o f t h e TDEM t o produce t h e m i s s i o n Cycle h o t s e c t i o n components, i n and a p o s t p r o c e s s i n g module. The e x e c u t i v e d i r e c t s t h e l o a d i n g on t h e i n d i v i d u a l r u n n i n g of each module, c o n t r o l s t h e f l o w o f d a t a among t h i s case t h e combustor. This s o f t w a r e t r a n s l a t e s t h e major e n g i n e performance parameter p r o f i l e s from t h e modules and c o n t a i n s t h e s e l f - a d a p t i v e c o n t r o l l o g i c .

F i g u r e 1 3 i s a f l o w c h a r t of t h e COSMO system showing TDEM i n t o p r o f i l e s o f t h e components thermodynamic The f o r m u l a s t h e d a t a f l o w and t h e a c t i o n p o s i t i o n s of t h e a d a p t i v e l o a d s ( p r e s s u r e s , temperatures, rpm).

' c o n t r o l s . The modular d e s i g n o f t h e system a l l o w s each a r e r e p r e s e n t a t i v e a n a l y t i c a l r e s u l t s f o r t h e c r i t i c a l subsystem t o be viewed as a p l u g - i n module which can be l i f e l o c a t i o n s .

r e p l a c e d w i t h a l t e r n a t e s . W i t h o u t t h e developments i n t h e s t r u c t u r a l a n a l y - The i d e a s , t e c h n i q u e s , and computer s o f t w a r e con- s i s a r e a of HOST t h i s t e s t s i m u l a t i o n would n o t have t a i n e d i n COSMO have p r o v e n t o be e x t r e m e l y v a l u a b l e i n been a t t e m p t e d because o f t h e e x c e s s i v e amounts of com- advancing t h e p r o d u c t i v i t y and d e s i g n a n a l y s i s c a p a b i l - p u t e r t i m e t h a t would have been r e q u i r e d . T h i s problem i t y o f combustors. T h i s s o f t w a r e i n c o n j u n c t i o n w i t h i s h i g h l y t i m e dependent and n u m e r i c a l l y s e n s i t i v e .

modern supercomputers i s a b l e t o reduce a d e s i g n t a s k The m a t e r i a l p r o p e r t i e s and t h e c r e e p p r o p e r t i e s d i f f e r which p r e v i o u s l y r e q u i r e d man-months o f e f f o r t o v e r a g r e a t l y among t h e t h r e e c o n s t i t u e n t s o f t h i s m a t e r i a l t i m e p e r i o d of months t o a one-man, l e s s t h a n a day system. An added n o n l i n e a r i t y o c c u r s due t o t h e e f f o r t . A l o n g w i t h t h i s t i m e compression comes growth o f an o x i d e s c a l e between t h e bond c o a t and t h e i n c r e a s e d a c c u r a c y f r o m t h e advanced m o d e l i n g and t o p c o a t . The dynamic t i m e i n c r e m e n t i n g a l g o r i t h m a n a l y s i s t e c h n i q u e s . As a r e s u l t o f t h i s , more a n a l y t - developed under t h e t h r e e - d i m e n s i o n a l i n e l a s t i c HOST i c a l d e s i g n s t u d i e s can be performed, r e d u c i n g t h e program made t h e a n a l y s i s o f t h i s n o n l i n e a r system chances f o r f i e l d s u r p r i s e s and t h e amount o f combustor poss i b l e .

t e s t i n g r e q u i r e d .

SSME HPFTP T u r b i n e Blade T u r b i n e Blade A n a l y s i s One f i n a l example o f t h e a p p l i c a t i o n o f HOST tech- The a n a l v s i s o f t u r b i n e b l a d e s i s an e x c e l l e n t n o l o a v I s t h e NASA Droaram w i t h t h e acronvm - SADCALM.

barometer o f t h e improvements b r o u g h t about by t h e HOST This-;tands f o r , " S k r u c t u r a l A n a l y s i s D e m b n s t r a t i o n o f program. There was a pre-HOST program c a l l e d , " T u r b i n e C o n s t i t u t i v e and L i f e Models." Under t h i s program, Blade T i p D u r a b i l i t y A n a l y s i s , " which e s t a b l i s h e d t h e c o a t e d s i n g l e c r y s t a l t u r b i n e b l a d e s such as t h e one s t a t e - o f - t h e - a r t p r i o r t o HOST. A commercial a i r - I n d i c a t e d i n F i g . 21 w i l l be a n a l y z e d by t h e most T h i s c o o l e d t u r b i n e b l a d e w i t h a well-documented h i s t o r y o f advanced t e c h n o l o g y developed under HOST.

c r a c k i n g I n t h e s q u e a l e r t i p r e g i o n was s u b j e c t e d t o i n c l u d e s t h e 20-noded i s o p a r a m e t r i c f i n i t e element c y c l i c n o n l i n e a r a n a l y s i s by a c o m m e r c i a l l y a v a i l a b l e and t h e c o n s t i t u t i v e models developed i n t h e t h r e e - computer program, ANSYS. T h i s t h r e e - d i m e n s i o n a l prob- d i m e n s i o n a l i n e l a s t i c programs. The s i n g l e c r y s t a l - lem had p r e v i o u s l y been analyzed, e l a s t i c a l l y , by an c r y s t a l l o g r a p h i c c o n s t i t u t i v e model developed under in-house computer program. A t t h e end o f t h e HOST pro- t h e a n i s o t r o p i c c o n s t i t u t i v e m o d e l i n g programs, and gram, t h i s p r o b l e m was once a g a i n used t o e s t a b l i s h t h e t h r e e HOST 1 i f e t h e o r i e s , " C y c l i c Damage Accumulation," changes b r o u g h t a b o u t by HOST. " T o t a l S t r a i n - S t r a i n Range P a r t i t i o n i n g . " and " H y s t e r - The p r o b l e m i n v o l v e d was t h e s i g n i f i c a n t creep- e t i c Energy," w i l l be used. T h i s program i n v o l v e s f a t i g u e encountered i n a Stage-1 h i g h - p r e s s u r e t u r b i n e t e s t i n g , a n a l y s i s , and c o r r e l a t i o n and w i l l p r o v i d e an b l a d e . These b l a d e s a r e h o l l o w , a i r - c o o l e d , and p a i r e d e x c e l l e n t o p p o r t u n i t y f o r d e m o n s t r a t i n g t h e b e n e f i t s of t o g e t h e r on a s i n g l e t h r e e - t a n g d o v e t a i l . F i g u r e 14 t h e HOST program.

shows one such b l a d e and i n d i c a t e s t h e r e g i o n o f a n a l y - s i s . The t h r e e - d i m e n s i o n a l f i n i t e - e l e m e n t model o f t h e CONCLUSIONS component b l a d e t i p above t h e 75-percent span was con- s t r u c t e d o f 580 e i g h t - n o d e d i s o p a r a m e t r i c b r i c k e l e - The i d e a s , t e c h n i q u e s , and computer s o f t w a r e deve- ments w i t h 1119 nodes. A d e t a i l e d , exploded v i e w o f l o p e d under t h e NASA HOST program have p r o v e n t o be t h i s model d e p i c t i n g t h e s q u e a l e r t i p , t i p cap, and e x t r e m e l y v a l u a b l e i n advancing t h e p r o d u c t i v i t y and s p a r as d i s c r e t e t h r e e - d i m e n s i o n a l components i s shown d e s i g n a n a l y s i s c a p a b i l i t y f o r h o t s e c t i o n s t r u c t u r e s i n F i g . 15. o f AGTE's. T h i s s o f t w a r e i n c o n j u n c t i o n w i t h modern T h i s ANSYS model was e x e r c i s e d on t h e CDC-7600 supercomputers i s a b l e t o reduce a d e s i g n t a s k computer. T h i s model had p r e v i o u s l y been r u n on t h e s i g n i f i c a n t l y . These i d e a s a r e amenable t o f u r t h e r TAMP-MASS computer program and t h e Honeywell 6000 com- generalizationlspecialization and e x t e n s i o n t o a i l w i l l p u t e r . I n 1986, t h i s model was c o n v e r t e d t o 580, areas o f t h e engine s t r u c t u r e . These t e c h n i q u e s 20-noded i s o p a r a m e t r i c f i n i t e elements and r u n on one have t h e i r m a j o r p a y o f f I n t h e n e x t g e n e r a t i o n o f aero- of t h e codes developed under, "Three-Dimensional space p r o p u l s i o n systems w i t h t h e i r i n c r e a s i n g l y l a r g e I n e l a s t i c A n a l y s i s Methods f o r Hot S e c t i o n S t r u c t u r e s . " number o f p a r a m e t r i c v a r i a t i o n s .

Table 1 shows t h e t i m e s and c o s t s experienced under t h e v a r i o u s c o n d i t i o n s . The impact of t h e advancements i n REFERENCES t e c h n o l o g y and computer hardware i s a p p a r e n t from t h i s t a b l e . M a f f e o , R . , 1985, "Burner L i n e r T h e r m a l / S t r u c t u r a l Load Modeling, TRANCITS Program U s e r ' s Manual," NASA Thermal B a r r i e r C o a t i n g A n a l y s i s CR-174891.

Another t e c h n o l o g i c a l a r e a i n t h e HOST program was McKnight, R.L., 1983, "Component S p e c i f i c Modeling; t h a t o f " S u r f a c e P r o t e c t i o n . " Programs were developed F i r s t Annual S t a t u s R e p o r t , " NASA CR-174765.

under t h i s a r e a t o produce an u n d e r s t a n d i n g and t o gen- McKnight, R.L., 1985, "Component S p e c i f i c Modeling; e r a t e t h e o r i e s and computer t o o l s for t h e d e s i g n , Second Annual S t a t u s Report," NASA CR-174925.

a n a l y s i s , and l i f e p r e d i c t i o n o f Thermal B a r r i e r Coat- McKnight, R.L., L a f l e n , J . H . , H a l f o r d , G . R . , and i n g s (TBC). F i g u r e 16 shows one t y p e o f t e s t specimen Kaufman, A . , 1983, " T u r b i n e Blade N o n l i n e a r S t r u c t u r a l i n v o l v e d i n t h i s e f f o r t . F i g u r e 17 shows t h e axisym- and L i f e A n a l y s i s , " J o u r n a l o f A i r c r a f t , Vol. 20, m e t r i c f i n i t e - e l e m e n t model used t o s i m u l a t e these t e s t NO. 5, pp. 475-480.

specimens. F i g u r e 18 i s a f u r n a c e thermal t e s t c y c l e McKnight, R.L., L a f l e n , J.H., and Spamer, G . T . , t h e s e specimens were c y c l e d t h r o u g h . F i g u r e s 19 and 20 1981, " T u r b i n e Blade T i p D u r a b i l i t y A n a l y s i s , " NASA CR- 165268.

T A B L E 1 . - T U R B I N E B L A D E T I P M O D E L H I S T O R Y

Y e a r C o m p u t e r F i n i t e e l e m e n t C o m p u t e r t i m e t i m e program 1 1 1975 TAMP-MASS 8-noded Honeywe isoparametric CDC-7600 24 hr 1981 A N S Y S 8-noded isoparametric CRAY-1 1986 H O S T 20-noded three- isoparametric i m e n s i o n a 1 d i ne1 a s t i c 0.2 0 40 Altitude, 1000 ft Figure 1. Engine Operating Map.

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Takeoff Power 2000" F Standard Day 400 psla 3 331 5 1 5 4 2 4 2 c - - 5 6 n c., IC Legend 0 Ambient 2C HP Compressor Inlet 3 H P Compressor Discharge 2 Engine Inlet 3 9 H P Turbine First-Stage Nozzle Inlet (Wllhout Cooling Flow) Fan Tip (Bypass) Slream Inlet 2 2 HP Turblne Rotor Inlet (With Cooling Flow) Fan Hub (LP Compressor) Stream Inlet I C 2 3 Fan Discharge 5 H P Turbine Discharge (Without Cooling Flow) 2 4 LP Compressor Discharge 5 1 HP Turbtne Discharge (Wlth Cooling Flow) 5 4 LP Turbine Inlet (Wilh Cooling Flow) Bypass Stream Mixing Plane 2 5 2 6 Bypass Duct Inlet (Altar Mixing) 5 LP Turblne Discharge (Wlthoul Coollng Flow) 5 6 LP Turbine DIsCharge (Wlth Cooling Flow) Bypass Ducl Jet Nozzle Throat 2 8 2 9 Bypass Ducl Nozzle Ex11 8 Primary Jet Nozzle Throat (Complete Expansion) 9 Primary Jet Nozzle Exit (Complete Expansion)

Pressure Fan -- - --

Temperature Fan - - - - - -

Core Figure 2. Aerodynamic Stations.

Engine 1 4 8 Flow Performance Engine Operating Path Cycle Map Station

Points _- --___ -

Engine Conditions 148 Cases + - -- -. --

Cycle -

--- - - -__ -

N,T,P,Nl, N2 M, H, To, De& W,T,P, Pwr. LVL at Each N1, N2 Station Cust. Bld, Detrn. LVL Engine Mission

_ _ _ _ - _

M, h, ATo, Pwr. LVL., Station Cust. Bid., Mission

- Engine

Detrn. LVL Profiles I n te rpolat io n + Station

-

Program -__--- Parameters W, T, P. N

__---___

Engine Versus W, T. P. N __+ Performance Time Cycle Map Figure 4 . Thermodynamic Engine Model.

a7 10 20 30 40 50 60 70 Time, minutes Figure 5. Typical Flight Cycle.

5 6

+

Pressure 1. Tap Locations Dome Upstream

+/y=\ / Dome Downstream

2.

3. Inner Passage, Upstream 4 . Inner Passage, Downstream 5 . Outer Passage, Downstream 6 . Combustor Downstream Figure 6. Rolled Ring Combustor.

2D Elodel Typical Nugget I 1 Physical Input Parameters

I

I I 3D ?lode1 Master Region Definition Figure 8. Combustor Nugget Finite Element Models.

Figure 7. Combustor Recipe Process.

Combustor Liner Parameter List Code Name Default Code Name Default X = Coordinate 1 x1 0.0 I c

_I

Figure 9. Combustor Liner Parameters.

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Figure 13. System Flowchart Showing Adaptive Control Positions.

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N89-20 142

FATIGUE L I F E PREDICTION MODELING FOR TURBINE HOT SECTION MATERIALS G. R. Halford National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio T. G. Meyer, R. S . Nelwn, D. M. Niisley, a d G. A. Swanwn United Technologies Pratt and Whitney East Hartford, Connecticut A B S T R A C T To-date, e f f o r t s h a v e c o n c e n t r a t e d o n d e v e l o p m e n t o f i n d e p e n d e n t m o d e l s f o r c y c l i c c o n s t i t u t i v e behav- T h i s p a p e r presents a s u m m a r y of t h e life predic- ior, c y c l i c c r a c k i n i t i a t i o n , and c y c l i c c r a c k propa- t i o n m e t h o d s d e v e l o p e d u n d e r the NASA Lewis Research gation. T h e t r a n s i t i o n b e t w e e n c r a c k initiation and C e n t e r ' s Hot S e c t i o n T e c h n o l o g y (HOST) program. A c r a c k p r o p a g a t i o n has not been t h o r o u g h l y r e s e a r c h e d m a j o r o b j e c t i v e of t h e f a t i g u e and f r a c t u r e e f f o r t s as y e t , and t h e i n t e g r a t i o n of t h e s e m o d e l s i n t o a u n d e r t h e H O S T program w a s t o s i g n i f i c a n t l y improve unified life p r e d i c t i o n method has not been a d d r e s s e d .

the a n a l y t i c life p r e d i c t i o n tools used by t h e aero- nautical g a s t u r b i n e e n g i n e industry. This has been a c h i e v e d in t h e a r e a s of high-temperature thermal and I N T R O D U C T I O N mechanical f a t i g u e of bare and coated high-temperature s u p e r a l l o y s . S u c h technical improvements will eventu- Background a l l y r e d u c e life cycle c o s t s .

Life c y c l e c o s t s r a n g i n g f r o m initial design T h e c y c l i c c r a c k i n i t i a t i o n and p r o p a g a t i o n c o s t s t o f i e l d r e p l a c e m e n t c o s t s o f limited d u r a b i l i t y r e s i s t a n c e of n o m i n a l l y isotropic p o l y c r y s t a l l i n e c o m p o n e n t parts a r e the d r i v i n g e l e m e n t s f o r improved a l l o y s a n d h i g h l y a n i s o t r o p i c s i n g l e crystal a l l o y s a n a l y t i c life p r e d i c t i o n capability. S i n c e life c y c l e has b e e n a d d r e s s e d . A s i z e a b l e d a t a base has been costs a r e t h e h i g h e s t f o r hot section g a s t u r b i n e g e n e r a t e d f o r t h r e e a l l o y s [cast P W A 1 4 5 5 (8-1900 + e n g i n e c o m p o n e n t s , o u r e f f o r t s have c o n c e n t r a t e d o n H f ) , w r o u g h t Inconel 718. a n d c a s t s i n g l e crystal P W A of the problems in t h i s area. A c c u r a t e c a l c u l a t i o n 14801 in b a r e a n d c o a t e d c o n d i t i o n s . T w o c o a t i n g s e x p e c t e d s e r v i c e lifetimes, i s crucial to t h e f i n a l s y s t e m s , d i f f u s i o n a l u m i n i d e ( P W A 273) and p l a s m a j u d g m e n t t o proceed w i t h a p a r t i c u l a r design. Inaccu- sprayed M C r A l Y o v e r l a y ( P W A 286) were employed.

rate life c a l c u l a t i o n s r e s u l t in o v e r l y e x p e n s i v e Life p r e d i c t i o n m o d e l i n g e f f o r t s w e r e d e v o t e d t o of potential designs--either f r o m an u n d e r u t i l i z a t i o n creep-fati g u e interaction, o x i d a t i o n , c o a t i n g s i nter- T h e f a t i g u e and f r a c t u r e o r a lack o f a d e q u a t e llfe.

a c t i o n s , m u l t i a x i a l i t y of stress-strain states, m e a n of t h e HOST program w a s initiated t o r e d u c e p o r t i o n s t r e s s e f f e c t s , c u m u l a t i v e d a m a g e , and t h e r m o m e c h a n i - life c y c l e c o s t s t h r o u g h improved a c c u r a c y of analytic cal f a t i g u e . T h e f a t i g u e c r a c k initiation life m o d e l s life p r e d i c t i v e models. T h e s p e c i f i c a r e a s of primary d e v e l o p e d t o d a t e i n c l u d e t h e C y c l i c D a m a g e A c c u m u l a - c o n c e r n a r e v e r y high-temperature cyclic c r a c k initia- t i o n (CDA) Model of P r a t t & W h i t n e y a n d t h e Total tion and p r o p a g a t i o n in both isotropic and anisotropic S t r a i n V e r s i o n of S t r a i n r a n g e P a r t i t i o n i n g (TS-SRP) of s u p e r a l l o y s used in hot s e c t l o n turbine engine NASA Lewis f o r n o m i n a l l y isotropic m a t e r i a l s , and t h e c o m p o n e n t s .

T e n s i l e H y s t e r e t i c E n e r g y Model of P r a t t & W h i t n e y f o r a n i s o t r o p i c superalloys. T h e f a t i g u e model being d e v e l o p e d by t h e General Electric C o m p a n y is based H O S T Life P r e d i c t i o n P r o g r a m upon t h e c o n c e p t s of Path-Independent I n t e g r a l s (PII) T a b l e I lists t h e s p e c i f i c programs that have f o r d e s c r i b i n g c y c l i c c r a c k g r o w t h u n d e r c o m p l e x non- supported t h e f a t l g u e a n d f r a c t u r e life prediction linear r e s p o n s e a t t h e c r a c k t i p d u e t o t h e r m o m e c h a n i - efforts. Each will be d i s c u s s e d and the most signifi- cal l o a d i n g conditions. A m i c r o m e c h a n i s t i c o x i d a t i o n c a n t of the n u m e r o u s a c c o m p l i s h m e n t s will be pointed c r a c k e x t e n s i o n model has been derived by r e s e a r c h e r s S p a c e d o e s not permit e l a b o r a t i o n o f the cumer- out.

a t S y r a c u s e University. T h e m o d e l s a r e d e s c r i b e d a n d o u s m e t h o d s n o r of t h e experimental details. The d i s c u s s e d in t h e paper. O n l y limited v e r i f i c a t i o n has r e a d e r is r e f e r r e d t o t h e m o r e t h o r o u g h l y documented been a c h i e v e d to-date a s several of the technical pro- original r e f e r e n c e s .

g r a m s a r e still in p r o g r e s s and the verification tasks a r e s c h e d u l e d , q u f t e n a t u r a l l y , n e a r the c o n c l u s i o n of t h e program.

PRECEDING PAGE FLANK NOT NEMED

I n a d d i t i o n t o t h e I n d u s t r i a l C o n t r a c t s and U n i - where v e r s i t y G r a n t s supported by t h e t h e HOST program, some f u n d i n g was s e t a s i d e t o r e j u v e n a t e a g i n g t e s t f a c i l i - N i i n i t i a t i o n l i f e , t r a n s g r a n u l a r mode t i e s i n t h e t h e a r e a o f f a t i g u e and f r a c t u r e . The - advanced, h i g h - t e m p e r a t u r e f a t i g u e and s t r u c t u r e s p r i m a r y c r e e p d u c t i l i t y =P r e s e a r c h l a b o r a t o r y a t Lewis (McGaw and B a r t o l o t t a , 1987) i s now o p e r a t i o n a l , and i n f a c t has grown t o t h e GNL n o n l i n e a r damage a c c u m u l a t i o n f u n c t i o n p o i n t o f r e q u i r i n g f u r t h e r expansion. The f a c i l i t y i s equipped w i t h t h e v e r y l a t e s t c l o s e d - l o o p , servo-

(g)R r e f e r e n c e c y c l i c damage r a t e

c o n t r o l l e d machinery, and most i m p o r t a n t l y b o a s t s a u n i q u e c o m p u t e r i z e d n e r v e c e n t e r for programmed t e s t c o n t r o l ; d a t a t a k i n g , s t o r a g e and r e t r i e v a l ; and d a t a maximum t e n s i l e s t r e s s i n c u r r e n t c y c l e r e d u c t i o n and p l o t t i n g .

uT uTR r e f e r e n c e maximum t e n s i l e s t r e s s ISOTROPIC MATERIAL MODELING PO s t r e s s range o f c u r r e n t c y c l e C y c l i c Crack I n i t i a t i o n The m a j o r i t y o f u s a b l e c y c l i c l i f e t i m e o f t u r b i n e PoR r e f e r e n c e s t r e s s range e n g i n e h o t s e c t i o n components i s u s u a l l y spent i n what i s c a l l e d t h e " c y c l i c c r a c k i n i t i a t i o n " p o r t i o n o f t h e DTD time-dependent damage r a t e m o d i f i e r f a t i g u e l i f e . S t r i c t l y speaking, c r a c k i n i t i a t i o n does i n d e e d c o n t a i n a c o n s i d e r a b l e amount o f c y c l i c c y c l i c o x i d a t i o n r a t e f o r c u r r e n t f a t i g u e fox c r a c k growth, a l t h o u g h t h e p h y s i c a l s i z e o f t h e c r a c k s cyc 1 e i s q u i t e s m a l l . From an e n g i n e e r i n g p o i n t o f view, any c r a c k g r o w t h below a c r a c k s i z e o f a p p r o x i m a t e l y r e f e r e n c e f a t i g u e l c y c l i c o x i d a t i o n r a t e foxR 0 . 8 nun (1132 i n . ) t y p i c a l l y i s i n c l u d e d i n t h e " i n i t i - a t i o n " p o r t i o n of t h e l i f e . J u s t i f i c a t i o n for t h i s The b a s i s f o r Eq. ( 1 ) i s e x p l a i n e d by Moreno d e f i n i t i o n i s based upon: ( a ) t h e i n a b i l i t y t o r e l i a - (1983). Moreno e t a l . (1984). and Nelson (1986). A b l y d e t e c t c r a c k s o f s m a l l e r s i z e , and ( b ) t h e i n a b i l - goal o f t h e program t o d e v e l o p t h e CDA model was t o i t y o f c y c l i c c r a c k g r o w t h laws t o a d e q u a t e l y model l i m i t t h e c o m p l e x i t y of t h e e x p e r i m e n t s t o d e t e r m i n e c y c l i c e x t e n s i o n of c r a c k s s m a l l e r t h a n t h i s s i z e .

t h e m a t e r i a l b e h a v i o r c o n s t a n t s . For example, o n l y Such a d e f i n i t i o n of c y c l i c c r a c k i n i t i a t i o n i s used monotonic c r e e p t e s t s and c o n t i n u o u s c y c l i n g f a t i g u e i n t h e development o f t h e P r a t t & Whitney C y c l i c Damage t o e v a l u a t e t h e c o n s t a n t s i n experiments a r e r e q u i r e d A c c u m u l a t i o n Model addressed i n t h e n e x t s e c t i o n .

t h e first t e r m of t h e CDA e x p r e s s i o n . The second t e r m P r a t t & Whitney C y c l i c Damaqe A c c u m u l a t i o n (CDA) r e q u i r e s t h a t c y c l i c o x i d a t i o n measurements be made

w. The i n t e r a c t i o n of c r e e p w i t h f a t i g u e a t h i g h

d u r i n g f a t i g u e t e s t i n g .

temperatures i s b e i n g s t u d i e d i n d e t a i l under N o n l i n e a r damage a c c u m u l a t i o n c a l c u l a t i o n s a r e NASA/HOST C o n t r a c t NAS3-23288, "Creep-Fati gue L i f e now p o s s i b l e f o r b o t h cycle-dependent and t i m e - P r e d i c t i o n f o r Engine Hot S e c t i o n M a t e r i a l s ( I s o - dependent, cases. Modular terms which c a p t u r e t h e t r o p i c ) " (Moreno, 1983, Moreno e t a l . , 1986, and e f f e c t s of m u l t i a x i a l i t y , c o a t i n g s , and i n t e r g r a n u l a r Nelson e t a l . , 1986). T h i s e f f o r t has i n v e s t i g a t e d c r a c k i n g a r e c u r r e n t l y under development. The a b i l i t y fundamental approaches t o h i g h t e m p e r a t u r e c r a c k o f t h e mode1 t o c o r r e l a t e thermomechanical f a t i g u e I n i t i a t i o n l i f e p r e d i c t i o n u s i n g a c a s t n i c k e l - b a s e 1 f o r b a r e and c o a t e d m a t e r i a l , d a t a i s shown i n F i g .

a l l o y , PWA 1455 (81900 + H f ) as t h e base m a t e r i a l .

Complete d e t a i l s o f t e s t c o n d i t i o n s r e s p e c t i v e l y .

D u r i n g t h e program, o v e r 157 specimen t e s t s were com- o f t h e employed a r e g i v e n b y Nelson (1986). Most p l e t e d under l o a d i n g c o n d i t i o n s which c o n s i s t e d o f thermomechanical f a t i g u e (TMF) t e s t s were p e r f o r m e d a t monotonic t e n s i l e and c r e e p t e s t s as w e l l as c o n t i n u - "C a t one CPM w i t h temperatures between 538 and 871 o u s l y c y c l e d f a t i g u e t e s t s . A r e v i e w o f e x i s t i n g s t r a i n ranges between 0 . 4 and t o t a l mechanical f a t i g u e models was conducted, and d e s i r a b l e f e a t u r e s 0.5 p e r c e n t . The dog-leg e x p e r i m e n t s u t i l i z e d 54 sec o f each o f t h e s e were i d e n t i f i e d . A new method o f h o l d p e r i o d s i n e i t h e r t e n s i o n or compression. Work h i g h t e m p e r a t u r e f a t i g u e l i f e p r e d i c t i o n c a l l e d C y c l i c c o n t i n u e s on a r e f i n e d v e r s i o n o f t h e model which w i l l Damage A c c u m u l a t i o n (CDA) was s u b s e q u e n t l y developed a t t e m p t t o c a p t u r e a l l t h e i m p o r t a n t l i f e t r e n d s seen w h i c h i n c o r p o r a t e s many of t h e s e f e a t u r e s .

d u r i n g t h e l a t t e r stages o f t h e c o n t r a c t .

Complex l o a d i n g s were i n t r o d u c e d d u r i n g t h e l a t - The f i n a l t a s k under t h e program i s t o p e r f o r m a t e r stages o f t h e program t o s t u d y t h e e f f e c t s o f s i m i l a r s e r i e s of t e s t s on an a l t e r n a t e a l l o y , wrought thermomechanical f a t i g u e , m u l t i a x i a l l o a d i n g , cumula- I n c o n e l 718. A t o t a l of 55 of these specimen t e s t s t i v e damage, environment, mean s t r e s s , and c o a t i n g s .

have now been completed, i n c l u d i n g i s o t h e r m a l , t h e r - An a d d i t i o n a l 160 s t r a i n - c o n t r o l l e d f a t i g u e t e s t s have momechanical f a t i g u e , and m u l t i a x i a l s t r a i n - c o n t r o l l e d been conducted as a p a r t of t h e s e t a s k s . Three d i f - I t i s expected t h a t t h e f i n a l f o r m o f t h e CDA t e s t s .

f e r e n t s u r f a c e t r e a t m e n t s were u t i l i z e d f o r t h e TMF and model may i n c l u d e a d d i t i o n a l r e f i n e m e n t s r e q u i r e d t o c o a t e d t e s t s : b a r e ( n o c o a t i n g ) , o v e r l a y N i C o C r A l Y p r e d i c t p r o p e r l y t h e l i f e t r e n d s f o r f o r g e d a l l o y s .

coated, and d l f f u s i o n a l u m i n i d e coated. S e v e r a l Lewis Research Center T o t a l S t r a i n V e r s i o n o f r e f i n e m e n t s have been i n c o r p o r a t e d i n t o t h e CDA l i f e S t r a i n r a n g e P a r t i t i o n i n g . The S t r a i n r a n g e P a r t i t i o n i n g p r e d i c t i o n model based on t h e r e s u l t s o f these com- ( S R P ) method for c h a r a c t e r i z i n g and p r e d i c t i n g creep- mu- p l e x t e s t s . The c u r r e n t form o f t h e model for acc of a l l o y s has l o n g been a s s o c i a t e d f a t i g u e b e h a v i o r ( 1 ) .

l a t e d t r a n s g r a n u l a r damage i s g i v e n by Eq.

w i t h u s i n g i n e l a s t i c s t r a i n s t o r e l a t e t o c y c l i c l i f e .

Recent advances by H a l f o r d and Saltsman (1983) and Saltsman and H a l f o r d (1985) now p e r m i t t h e approach t o dN be expressed i n terms of t o t a l s t r a i n range v e r s u s c y c l i c l i f e . These developments make t h e SRP method more a t t r a c t i v e for a p p l i c a t i o n t o l i f e p r e d i c t i o n o f a e r o n a u t i c a l gas t u r b i n e h o t s e c t i o n components.

( 1 ) i j = pp, cc, pc, or cp where Here, m a t e r i a l s and l o a d i n g c o n d i t i o n s r e s u l t i n s t r a i n l e v e l s t h a t , w h i l e t h e y a r e severe and produce The c y c l i c s t r a i n h a r d e n i n g exponent, n, i n Eq. ( 4 ) i s l o w - c y c l e f a t i g u e c r a c k i n g , i n v o l v e o n l y s m a l l o b t a i n e d f r o m c o m p l e t e l y r e v e r s e d r a p i d s t r a i n - c y c l i n g amounts o f i n e l a s t i c d e f o r m a t i o n w i t h i n n o m i n a l l y PP r e s u l t s , e l a s t i c s t r a i n f i e l d s . The l i m i t e d i n e l a s t i c i t y produced l o c a l l y may e x e r t a s i g n i f i c a n t i n f l u e n c e on l i f e . The t y p e o f i n e l a s t i c s t r a i n s p r e s e n t ( t i m e - = K ( A E ) n AE ( 7 ) dependent creep and time-independent p l a s t i c i t y ) and el.PP PP PP t h e d i r e c t i o n o f t h e s t r a i n s ( t e n s i o n o r compression) For c y c l e s i n v o l v i n g creep, can be q u i t e i m p o r t a n t i n g o v e r n i n g t h e r e s u l t a n t c y c l i c c r a c k i n i t i a t i o n l i f e . The t o t a l s t r a i n based = K . ( A E . . ) n SRP approach (TS-SRP) has been developed t o d e a l ( 8 ) A E e l , i j i j i j e x p l i c i t l y w i t h t h e above c o n d i t i o n s . A b r i e f d e s c r i p t i o n i s g i v e n below to show how t h e procedures A complete nomenclature for TS-SRP i s g i v e n by a r e emp 1 oyed .

Saltsman (1988).

The t o t a l s t r a i n range, A E ~ , i s t h e sum o f two To a p p l y t h e TS-SRP approach, t h e s p e c i f i c terms, t h e e l a s t i c , A E ~ ~ , and t h e i n e l a s t i c , kin, m i s s i o n c y c l e s o f i n t e r e s t a r e i d e n t i f i e d and t h e s t r a i n ranges. Each s t r a i n range i s r e l a t e d t o c y c l i c c y c l i c s t r e s s - s t r a i n - t e m p e r a t u r e - t i m e h i s t o r y i s l i f e by a power law r e l a t i o n as shown i n Eq. ( 2 and determined a t t h e c r i t i c a l l o c a t i o n i n t h e s t r u c t u r a l F i g . 2 .

component. Then, t h e a p p r o p r i a t e e l a s t i c and i n e l a s - t i c s t r a i n range versus l i f e r e l a t i o n s a r e c a l c u l a t e d A E ~ = A E ~ ~ + Acin = B(Nf) b + C ' ( N f ) C and added t o g e t h e r t o o b t a i n t h e d e s i r e d t o t a l s t r a i n ( 2 ) range versus c y c l i c l i f e diagram. E n t e r i n g t h e d i a - gram w i t h t h e known t o t a l s t r a i n range, t h e c y c l i c To a p p l y Eq. ( 2 ) a t h i g h temperatures r e q u i r e s he l i f e i s determined d i r e c t l y w i t h o u t h a v i n g t o c a l c u - e v a l u a t i o n o f t h e c o e f f i c i e n t s , B and C ' , and t h e l a t e t h e magnitude o f t h e i n e l a s t i c s t r a i n range.

exponents, b and c . I t i s assumed, i n i t i a l l y t h a t l i f e p r e d i c t i o n c a l c u l a t i o n s by t h e TS-SRP Example b and c a r e c o n s t a n t s for a l l c o n d i t i o n s a t a g i v e n approach have been r e p o r t e d by H a l f o r d and Sal tsman t e m p e r a t u r e , i . e . , t h e y a r e t i m e - and waveshape- (1983), Moreno e t a l . (1985). and Saltsman and H a l f o r d independent, and t h a t B and C ' a r e time- and c y c l e (1988). The degree o f success o f t h e method i s shown waveshape-dependent.

i n F i g . 3. Here, t h e TS-SRP method was a p p l i e d by To d e t e r m i n e C ' , as many o f t h e f o u r b a s i c SRP Moreno e t a l . (1985) t o a s e r i e s o f f i v e d i f f e r e n t i n e l a s t i c s t r a i n range v e r s u s l i f e r e l a t i o n s , PP, CC, types o f complex v e r i f i c a t i o n experiments performed on PC, and CP, as a r e r e q u i r e d f o r t h e c y c l e o f i n t e r e s t t h e n i c k e l - b a s e s u p e r a l l o y , 81900 + H f . A d i r e c t com- must be known. H o w t h e i n e l a s t i c s t r a i n s a r e p a r t i - p a r i s o n o f t h e TS-SRP approach w i t h t h e CDA model a l s o t i o n e d w i t h i n t h e c y c l e must a l s o be known, i . e . , how was made by Moreno e t a l . (1985). wherein t h e p r i n c i - of PP, CC, PC, or CP s t r a i n r much o f each t y p e p a l f e a t u r e s o f each method were emphasized. The i s p r e s e n t i n t h e h y s t e r e s i s l o o p . Experimental TS-SRP model and t h e P r a t t & Whitney CDA model were f o r e s t a b l i s h i n g t h e four i n e l a s t i c SRP procedures b o t h designed f o r a p p l i c a t i o n t o s t r a i n - d r i v e n f a t i g u e l i f e r e l a t i o n s , t e c h n i q u e s f o r a p p r o x i m a t i n g them, l o a d i n g c o n d i t i o n s i n t h e n o m i n a l l y e l a s t i c regime.

e x p e r i m e n t a l p a r t i t i o n i n g procedures a r e g i v e n by Both methods a r e c u r r e n t l y b e i n g adapted f o r a p p l i c a - H i r s c h b e r g and H a l f o r d (1976), H a l f o r d e t a l . (197 t i o n t o TMF problems.

and Manson e t a l . (1975). r e s p e c t i v e l y .

I n p r i n c i p l e , t h e p a r t i t i o n i n g and t h u s t h e d e t e r m i n a t i o n o f C ' c o u l d be accomplished a n a l y t C y c l i c Crack P r o p a g a t i o n tal l y u s i n g advanced c y c l i c c o n s t i t u t i v e e q u a t i o n s o f c r a c k s and d e f e c t s i n t u r b i n e C v c l i c a r o w t h such as those developed under t h e NASA/HOST Program by e n g i n e - h o t s e c t i o n components i s o f c o n s i d e r a b l e con- L i n d h o l m (1984) and Ramaswamy e t a l . (1985). Advanced c e r n because o f t h e l a c k o f s t r u c t u r a l redundancy i n c y c l i c c o n s t i t u t i v e models a r e capable o f computing t h e c o n s t r u c t i o n o f these components. A s such, c r a c k t h e e x a c t d e t a i l s o f a s t r e s s - s t r a i n h y s t e r e s i s loop.

growth t o a c r i t i c a l f r a c t u r e s i z e must by a v o i d e d t o know1 ng o n l y t h e imposed temperature, t o t a l mechanical p r e v e n t c a t a s t r o p h i c f a s t f r a c t u r e and subsequent l o s s s t r a i n s , and how t h e y v a r y w i t h t i m e f o r a r e p r e s e n t a - o f e n g i n e f u n c t i o n . T y p i c a l l y , concern f o r f a s t f r a c - t i v e c y c l e . D e t a i l s o f t h e i n e l a s t i c s t r a i n i n g r a t e s t u r e i s a s s o c i a t e d more w i t h r o t a t i n g components t h a n a r e a l s o computable, and hence creep s t r a i n s ( t i m e - w i t h s t a t i c s t r u c t u r e s . For combustor l i n e r s , g u i d e dependent) and p l a s t i c s t r a i n s (time-independent) can vanes, s t a t i o n a r y spacers, and o t h e r n o n r o t a t i n g com- be separated, i . e . , p a r t i t i o n e d . I f a c o n s t i t u t i v e ponents, concern f o r c y c l i c c r a c k growth i s more eco- model i s n o t a v a i l a b l e , t h e e m p i r i c a l approach p r e - nomic i n n a t u r e t h a n s a f e t y - r e l a t e d . I n t h e HOST sented by Saltsman and H a l f o r d (1988) can be used t o f a t i g u e and f r a c t u r e program, two approaches t o c r a c k d e t e r m i n e C ' and B. The r e q u i r e d e q u a t i o n s a r e growth were taken. An e n g i n e e r i n g methodology was summarized below.

a p p l i e d i n an a t t e m p t t o develop d i r e c t l y u s e f u l d e s i g n t o o l s . and a s c i e n t i f i c approach examined t h e C micromechanisms o f c r a c k e x t e n s i o n a t t h e c r y s t a l 10- C ' = [ x F i j ( C l j ) l / c ] (3) g r a p h i c l e v e l and t h e i n t e r a c t i o n w i t h o x i d a t i o n phenomena.

General E l e c t r i c Path-Independent I n t e g r a l model.

(4) A major goa1 o f t h e c o n t r a c t program w i t h t h e Genera?

E l e c t r i c Company i s t o develop r e l i a b l e and a c c u r a t e e n g i n e e r i n g l i f e p r e d i c t i o n c a p a b i l i t i e s t o deal with c y c l i c c r a c k growth a t e l e v a t e d temperatures. Several o f t h e Path-Independent I n t e g r a l s , Jx, t h a t have been proposed o v e r t h e p a s t few y e a r s have been shown t o be ( 6 ) a p p l i c a b l e t o f r a c t u r e mechanics c a l c u l a t i o n s o f da/dN = m &a ( 1 1 ) c y c l i c c r a c k g r o w t h under u n i f o r m and n o n u n i f o r m t h e r - mal g r a d i e n t s and thermomechanical l o a d i n g s . S p e c i f i - From Eqs. ( 9 ) t o ( 1 ) we o b t a i n , c a l l y , t h e v a r i o u s Jx i n t e g r a l s proposed by Tada e t a l . (1973). A i n s w o r t h e t a l . (1978). B l a c k b u r n da/dN = P ' A t D f ) ( B / t i a ) l - " / " e t a l . (1977). K i s h i m o t o e t a l . (1980). and A t l u r i H gb (1982) have been f o u n d s u i t a b l e f o r a n a l y s i s o f c r a c k (12) s t r e s s f i e l d s i n v o l v i n g n o n l i n e a r and time-dependent thermomechanical response ( K i m and Orange, 1988). The Note t h a t da/dN s i n v e r s e l y p r o p o r t onal t o f r e - t r a d i t i o n a l R i c e J - i n t e g r a l ( R i c e , 1968). however, quency. f. F i g u r e 5 t a k e n from L i u and Oshida (1986) becomes p a t h dependent and l o s e s i t s p h y s i c a l s i g n i f i - i 1 l u s t r a t e s t h e success t h e approach has had i n c o r r e - cance f o r thermomechanical l o a d i n g s . F i g u r e 5 com- l a t i n g c r a c k growth under h i g h t e m p e r a t u r e e n v i r o n - pares t h e r e s u l t s of a s e r i e s of c a l c u l a t i o n s a p p l i e d ments. The e x p e r i m e n t a l r e s u l t s shown i n t h e f i g u r e t o an i n s t r u m e n t e d s i n g l e edge n o t c h specimen o f I n c o - were o b t a i n e d from t h e open l i t e r a t u r e .

ne1 718 w i t h a l i n e a r thermal g r a d i e n t . The c u r r e n t program w i t h t h e General E l e c t r i c Company w i l l con- t i n u e i n t o 1989, d u r i n g which t i m e one o f t h e p a t h - ANISOTROPIC MATERIAL MODELING independent i n t e g r a l s w i l l be s e l e c t e d f o r f u r t h e r v e r i f i c a t i o n under r e a l i s t i c thermomechanical l o a d i n g P r a t t & Whitney s i n g l e c r y s t a l c o n s t i t u t i v e c o n d i t i o n s f o u n d i n t h e h o t s e c t i o n o f gas t u r b i n e Because o f t h e e x c e p t i o n a l l y s t r o n g l i n k m.

e n g i n e s .

between t h e c y c l i c d e f o r m a t i o n mechanisms i n s i n g l e Syracuse U n i v e r s i t y o x i d a t i o n c r a c k e x t e n s i o n c r y s t a l a l l o y s and t h e f a t i g u e c r a c k i n i t i a t i o n proc-

m. L i u and Oshida (1986) and Oshida and L i u (1988)

ess, i t was deemed a d v i s a b l e t o develop b o t h t h e have t a k e n a m i c r o m e c h a n i s t i c approach t o d e a l i n g w i t h c y c l i c c o n s t i t u t i v e and c y c l i c c r a c k i n i t i a t i o n l i f e c r a c k p r o p a g a t i o n i n s u p e r a l l o y s . A model o f i n t e r - p r e d i c t i o n models w i t h i n a s i n g l e program. F u r t h e r - m i t t e n t m i c r o - r u p t u r e o f g r a i n boundary o x i d e has been more, s i n c e s i n g l e c r y s t a l a l l o y s i n v a r i a b l y r e q u i r e proposed f o r h i g h t e m p e r a t u r e f a t i g u e c r a c k e x t e n s i o n .

a p r o t e c t i v e c o a t i n g f o r successful h i g h - t e m p e r a t u r e The model i s o u t l i n e d b r i e f l y below f o r t h e case o f a a p p l i c a t i o n s , i t was a l s o necessary to develop a t r a p e z o i d a l waveform.

c y c l i c c o n s t i t u t i v e and l i f e model f o r t h e c o a t i n g Oxygen a r r i v i n g a t a g r a i n boundary c r a c k t i p systems. The c o n s t i t u t i v e models w i l l be d i s c u s s e d must d i f f u s e i n t o t h e r e g i o n ahead o f t h e c r a c k i n i n t h e f o l l o w i n g s e c t i o n .

o r d e r t o form o x i d e a l o n g t h e g r a i n boundary. When A u n i f i e d c o n s t i t u t i v e model has been f o r m u l a t e d t h e c r a c k t i p g r a i n boundary o x i d e , a t a g i v e n s t r e s s for PWA 1480 s i n g l e c r y s t a l m a t e r i a l and i s c u r r e n t l y l e v e l , reaches a c r i t i c a l s i z e , &a. t h e o x i d e w i l l i n t h e f i n a l stages o f development. The model uses r u p t u r e and t h e c r a c k w i l l grow by t h e amount, 6a.

t h e u n i f i e d approach f o r computing a l l i n e l a s t i c The c r i t i c a l s i z e , 6 a , depends on t h e s t r e s s i n t e n s i t y s t r a i n r a t h e r t h a n t h e c o n v e n t i o n a l approach o f t r e a t - l e v e l d u r i n g t h e h o l d i n g p e r i o d . Once t h e c r a c k t i p i n g c r e e p and p l a s t i c i t y s e p a r a t e l y . The model has advanced t o i t s new p o s i t i o n , t h e process o f g r a i n assumes t h a t a l l i n e l a s t i c b e h a v i o r r e s u l t s from shear boundary d i f f u s i o n . g r a i n boundary o x i d a t i o n , and s t r a i n s on each o f t h e t w e l v e o c t a h e d r a l and s i x cube m i c r o - r u p t u r e o f t h e o x i d e i s r e p e a t e d . T h i s process s l i p systems and t h a t t h e g l o b a l i n e l a s t i c s t r a i n s a r e o f m i c r o - r u p t u r e of a c r a c k t i p g r a i n boundary can s i m p l y t h e sum of these s l i p systems s t r a i n s . S l i p r e c u r i n t e r m i t t e n t l y d u r i n g a f a t i g u e c y c l e , and i n system i n e l a s t i c shear s t r a i n r a t e s a r e governed by a f a c t . many m i c r o - r u p t u r e s can t a k e p l a c e . A f t e r each s e t o f v i s c o p l a s t i c e q u a t i o n s which i n v o l v e t h e s l i p t h e p e n e t r a t i o n of g r a i n boundary o x i d e m i c r o - r u p t u r e .

system s t r e s s e s and two e v o l u t i o n a r y s t a t e v a r i a b l e s .

must s t a r t a l l o v e r a g a i n from a " t i m e " z e r o . The The g e n e r a l form o f t h e e q u a t i o n g o v e r n i n g i n e l a s t i c t i m e i n t e r v a l , &t, necessary t o r e a c h t h e c r i t i c a l shear s t r a i n on t h e r t h s l i p system as g i v e n by s i z e , Sa, i s g i v e n by, i s , Swanson (1987) 6 t = (B/Dgb)(6a/I3W1 In ( 9 ) (13) where where B magnitude o f t h e d i f f u s i o n jumping v e c t o r o r i n t e r a t o m i c s p a c i n g i n e l a s t i c shear s t r a i n r a t e on t h e s l i p system yr Dgb g r a i n boundary d i f f u s i o n c o e f f i c i e n t e f f e c t i v e s t r e s s a c t i n g on t h e s l i p system nr t3.13' p r o p o r t i o n a l i t y c o n s t a n t s back s t r e s s a c t i n g on t h e s l i p system wr n p o s i t i v e exponent ( l e s s t h a n u n i t y ) K d r a g s t r e s s a c t i n g on t h e s l i p system The number o f m i c r o - r u p t u r e s d u r i n g t h e h o l d i n g pe- r i o d , AtH. I S . t o i n c l u d e s e v e r a l The model has been f o r m u l a t e d e f f e c t s t h a t have been r e p o r t e d t o i n f l u e n c e deforma- t i o n . These i n c l u d e c o n t r i b u t i o n s from s l i p system (10) s t r e s s e s o t h e r t h a n t h e Schmid shear s t r e s s , l a t e n t h a r d e n i n g due t o simultaneous s t r a i n i n g on a l l s l i p m i s l i n e a r l y p r o p o r t i o n a l t o t h e h o l d i n g p e r i o d and systems, and c r o s s - s l i p from t h e o c t a h e d r a l t o t h e i s i n v e r s e l y p r o p o r t i o n a l t o t h e f r e q u e n c y .

cube s l i p systems.

A l a r g e body o f i s o t h e r m a l c o n s t i t u t i v e d a t a has F a t i g u e c r a c k growth p e r c y c l e i s t h e sum o f t h e been o b t a i n e d a t temperatures r a n g i n g f r o m 427 t o m i c r o - r u p t u r e s d u r i n g t h e h o l d i n g p e r i o d , 1149 "C u s i n g u n i a x i a l specimens o r i e n t e d i n t h e

Nf = Nc + Nsc + Nsp

t o o l > , <011>, < 1 1 1 > , <123> c r y s t a l o r i e n t a t i o n s . The

c o n s t i t u t i v e model c o n s t a n t s have been d e t e r m i n e d from or (14) these i s o t h e r m a l t e s t s . F i g u r e s 6 and 7 show t h e measured s t r e s s s t r a i n b e h a v i o r and t h e c a l c u l a t e d Nf = N s i + Nsp c o n s t i t u t i v e model b e h a v i o r a t 871 "C. The model i s c u r r e n t l y b e i n g e v a l u a t e d a g a i n s t t h e s t r e s s - s t r a i n whichever i s t h e s m a l l e s t .

response o f thermomechanical f a t i g u e (TMF) t e s t s which were conducted f o r l i f e modeling. The s i n g l e c r y s t a l where c o n s t i t u t i v e model as w e l l as t h e c o a t i n g c o n s t i t u t i v e model r e p o r t e d below a r e c o m p a t i b l e w i t h a commer- c y c l e s t o i n i t i a t e a c r a c k t h r o u g h t h e c o a t i n g c i a l l y a v a i l a b l e f i n i t e element comDuter code.

Nc P r a t t & Whitney c o a t i n g c o n s t i t u t i v e model. Ther- c y c l e s for c o a t i n g i n i t i a t e d c r a c k to p e n e t r a t e momechanical f a t i a u e (TMF) c r a c k s i n t u r b i n e a i r f o i l s N s c a s m a l l d i s t a n c e i n t o t h e s u b s t r a t e o f P W A 1480 m a t e r i a l g e n e r a l l y o r i g i n a t e from a c o a t - i n g c r a c k . Thus, f o r a i r f o i l l i f e p r e d i c t i o n , i t i s c y c l e s t o i n i t i a t e a s u b s t r a t e c r a c k due t o i m p o r t a n t t o model t h e c o a t i n g mechanical b e h a v i o r as N s i macroscopic s l i p , o x i d a t i o n e f f e c t s , or d e f e c t s w e l l as t h a t o f t h e PWA 1480. I n t h i s program, v i s c o - f o r p l a s t i c c o n s t i t u t i v e models a r e b e i n g developed two f u n d a m e n t a l l y d i f f e r e n t c o a t i n g t y p e s which a r e N s p c y c l e s t o propagate s u b s t r a t e c r a c k t o f a i l u r e commonly used i n gas t u r b i n e s t o p r o v i d e o x i d a t i o n Nf t o t a l c y c l e s t o f a i l specimen or component p r o t e c t i o n : ( 1 ) a plasma sprayed NiCoCrAlY o v e r l a y c o a t i n g , and ( 2 ) a p a c k - c e m e n t a t i o n - a p p l i e d N i A l d i f - The f o l l o w i n g m o d i f i e d t e n s i l e h y s t e r e t i c energy model f u s i o n c o a t i n g .

was developed f o r t h e o v e r l a y c o a t i n g , The i s o t r o p i c f o r m u l a t i o n o f Walker (1981) was chosen as t h e o v e r l a y c o a t i n g c o n s t i t u t i v e model, based on i t s a b i l i t y t o r e p r o d u c e i s o t h e r m a l and t h e r - (15) momechanical h y s t e r e s i s l o o p d a t a r e p o r t e d by Swanson e t a l . (1987). The p r e d i c t e d o v e r l a y c o a t i n g response where o f an out-of-phase thermomechanical c y c l e i s compared t o d a t a i n F i g . 8. For t h e s e purposes, s o l i d c y l i n - d r i c a l specimens o f c o a t i n g m a t e r i a l were c u t from a ; v 5 1.0 v = (16) r ( T i ) b i l l e t p r e p a r e d by h o t i s o s t a t i c p r e s s i n g o f m a t e r i a l powder. The a l u m i n i d e d i f f u s i o n c o a t i n g c o n s t i t u t i v e

c r(To) ti - Do

model i s c u r r e n t l y under development, and w i l l be more cyc 1 e d i f f i c u l t t o d e t e r m i n e owing t o t h e f a c t t h a t i t w i l l be i m p o s s i b l e t o make s o l i d specimens o f stand-alone r ( T ) ro exp(-Q/T) temperature- and time-dependent c o a t i n g m a t e r i a l .

damage r a t e AWt t e n s i l e h y s t e r e t i c energy, N-m/m3 ( 1 n-1 b f / i n .3) C y c l i c Crack I n i t i a t i o n D i r e c t i o n a l l y c a s t , a n i s o t r o p i c , n i c k e l - b a s e T i i n d i v i d u a l t e m p e r a t u r e l e v e l s i n t h e t h e c y c l e , s u p e r a l l o y s ( p a r t i c u l a r l y s i n g l e c r y s t a l s ) e x h i b i t K ( O R ) g r e a t e r c r e e p - f a t i g u e r e s i s t a n c e t h a n t h e i r conven- t i o n a l l y c a s t p o l y c r y s t a l l i n e c o u n t e r p a r t s . To t a k e ti t i m e (min) a t T i . i n c l u d i n g 100 p e r c e n t o f f u l l advantage o f these improved m a t e r i a l p r o p e r t i e s , t e n s i l e h o l d and 30 p e r c e n t o f compressive h o l d however, r e q u i r e s t h e development o f a c c u r a t e c y c l i c t i m e s i n t h e c y c l e , i f any c o n s t i t u t i v e and l i f e p r e d i c t i o n models f o r these h i g h l y d i r e c t i o n a l a l l o y s . D i r e c t m o d i f i c a t i o n o f To t h r e s h o l d temperature for temperature dependent p o l y c r y s t a l l i n e b e h a v i o r models i s inadequate, and a damage, assumed to be 1088 K (1960 O R ) new approach t h a t r e c o g n i z e s t h e micromechanisms o f c r y s t a l response i s necessary. U n f o r t u n a t e l y , t h e DO " i n c u b a t i o n damage" program was a b l e t o address o n l y t h e c r a c k i n i t i a t i o n a s p e c t s o f s i n g l e c r y s t a l s u p e r a l l o y s . C y c l i c c r a c k e f f e c t i v e a c t i v a t i o n energy f o r temperature- Q g r o w t h l i f e p r e d i c t i o n m o d e l i n g must a w a i t f u t u r e e f - and time-dependent damage.

f o r t s .

The term, v , i s an e x t e n s i o n o f t h e O s t e r g r e n (1976) P r a t t & Whitney c o a t i n g and s i n g l e c r y s t a l l i f e time-dependent damage f r e q u e n c y term. A s used h e r e i n , p r e d i c t i o n model. G e n e r a l l y , a l l c o a t e d PWA 1480 i t i n c l u d e s b o t h temperature- and time-dependent damage

o r i e n t a t i o n s ( i . e . , cool>, <011>. < 1 1 1 > , and <123>)

f u n c t i o n s to model t h e r m a l l y a c t i v a t e d processes.

which were t e s t e d i n thermomechanical f a t i g u e i n i t i a t - Model c o n s t a n t s were determined from i s o t h e r m a l ed c r a c k s i n t h e metal a t s i t e s where c o a t i n g c r a c k - t e s t s conducted a t 427, 760, 927, and 1038 O C (800, i n g had o c c u r r e d . I s o t h e r m a l t e s t s o f c o a t e d <001> 1400, 1700, and 1900 O F ) . C o a t i n g h y s t e r e s i s loops PWA 1480 a l s o t y p i c a l l y i n i t i a t e d c r a c k s first i n t h e were p r e d i c t e d u s i n g t h e P W A 286 c o n s t i t u t i v e model c o a t i n g l a y e r . However, many coated non- <001> i n c o r p o r a t e d i n t o a one-dimensional model. T h i s model i s o t h e r m a l f a t i g u e t e s t s i n i t i a t e d c r a c k s underneath determines t h e s t r e s s - s t r a i n o f t h e s u b s t r a t e and t h e specimen o u t e r s u r f a c e i n e i t h e r t h e P W A 1480 o r c o a t i n g by imposing an e q u i v a l e n t displacement h i s t o r y .

t h e coating/PWA 1480 i n t e r f a c i a l r e g i o n . I n i t i a t i o n D i f f e r e n c e s i n c o e f f i c i e n t s o f thermal expansion a r e o c c u r r e d predominate y a t p o r o s i t y s i t e s .

i n c l u d e d i n t h e model.

The f o l l o w i n g 1 f e p r e d i c t i o n approach was deve- The model u n i f i e s i s o t h e r m a l and TMF p r e d i c t e d l o p e d t o account f o r t h e observed specimen c r a c k i n g l i v e s w i t h i n a f a c t o r o f about 2.5, as seen i n F i g . 9.

modes, G e n e r a l l y , t h e worst p r e d i c t e d t e s t l i v e s were 1 i m i t e d t o 1149 "C (2100 O F ) maximum temperature TMF t e s t s .

o f these t e s t r e s u l t s s h o u l d improve when P r e d i c t i o n A t l u r i . S . N . , 1982, "Path-Independent I n t e g r a l s i n 1149 " C (2100 " F ) i s o t h e r m a l t e s t s a r e i n c l u d e d i n t h e F i n i t e E l a s t i c i t y and I n e l a s t i c i t y , w i t h Body Forces, to determine model c o n s t a n t s .

d a t a s e t used I n e r t i a , and A r b i t r a r y Crack-Face C o n d i t i o n s , " A d d i t i o n a l model m o d i f i c a t i o n w i l l be necessary E n g i n e e r i n g F r a c t u r e Mechanics, Vol. 16, No. 3.

t o i n c l u d e t h e e f f e c t o f b i a x i a l c o a t i n g l o a d s i n t r o - pp. 341-364.

duced by t h e thermal g r o w t h mismatch between t h e c o a t - i n g and t h e s u b s t r a t e d u r i n g u n i a x i a l TMF t e s t s and B l a c k b u r n , W.S., Jackson, A . D . , and H e l l e n , T.K., engine t r a n s i e n t s .

1977, "An I n t e g r a l A s s o c i a t e d w i t h t h e S t a t e o f a PWA 273 a l u m i n i d e c o a t i n g and PWA 1480 c r a c k Crack T i p i n a N o n e l a s t i c M a t e r i a l , " I n t e r n a t i o n a l i n i t i a t i o n model development f o r c a l c u l a t i n g N s c , J o u r n a l o f F r a c t u r e , V o l . 13, No. 2, pp. 183-200.

Nsp, and Nsi i s c u r r e n t l y i n p r o c e s s . A t p r e s e n t , based on i s o t h e r m a l f a t i g u e c o r r e l a t i o n s , t h e most H a l f o r d , G . R . , Saltsman, J . F . , and H i r s c h b e r g , M.H., p r o m i s i n g c a n d i d a t e models f o r these m a t e r i a l s a r e 1977, " D u c t i l i t y N o r m a l i z e d - S t r a i n r a n g e P a r t i t i o n i n g a l s o d e r i v e d f r o m an approach based on h y s t e r e t i c L i f e R e l a t i o n s f o r Creep-Fatigue L i f e P r e d i c t i o n , " energy. Environmental D e g r a d a t i o n o f E n g i n e e r i n g M a t e r i a l s , M.R. Louthan and R.P. M c N i t t , eds., V i r g i n i a Tech.

P r i n t i n g Dept., V . P . I . and S t a t e U n i v e r s i t y , CONCLUDING REMARKS B l a c k s b u r g , V A , pp. 599-612. (NASA TM-73737).

I n c o n c l u s i o n , we would l i k e t o emphasize t h a t H a l f o r d , G.R. and Saltsman, J.F., 1983. " S t r a i n r a n g e s i g n i f i c a n t accomplishments have been achieved i n t h e P a r t i t i o n i n g - A T o t a l S t r a i n r a n g e V e r s i o n , " Advances f a t i g u e and f r a c t u r e arena t h r o u g h t h e atmosphere c r e - i n L i f e P r e d i c t i o n Methods, D.A. Woodford and a t e d by t h e HOST P r o j e c t . W e a r e now much b e t t e r a b l e J.R. Whitehead, eds.. ASME, New York. pp. 17-26.

t o deal w i t h d u r a b i l i t y enhancement i n t h e a e r o n a u t i - c a l p r o p u l s i o n i n d u s t r y t h r o u g h t h e o r e t i c a l , a n a l y t i - H i r s c h b e r g , M.H. and H a l f o r d , G . R . , "Use o f S t r a i n - c a l , and e x p e r i m e n t a l approaches. Given t h e a b i l i t y range P a r t i t i o n i n g t o P r e d i c t High-Temperature Low- t o complete t h e t a s k s we have s t a r t e d , we e x p e c t t o C y c l e F a t i g u e L i f e , " NASA TN D-8072, 1976.

r e a p even g r e a t e r rewards i n t h e near f u t u r e .

The m a j o r accomplishments t o - d a t e a r e summarized K i m , K . S . , and Orange, T.W., 1988, " A Review o f below: Path-Independent I n t e g r a l s i n E l a s t i c - P l a s t i c F r a c t u r e Mechanics," F r a c t u r e Mechanics: 1 8 t h N a t i o n a l Sympo- 1 . An advanced h i g h - t e m p e r a t u r e f a t i g u e and sium, ASTM STP-945. ASTM, P h i l a d e l p h i a , PA, I n Press.

s t r u c t u r e s r e s e a r c h l a b o r a t o r y has been implemented (See a l s o NASA CR-174956).

a t t h e NASA Lewis.

K i s h i m o t o , K., A o k i . S., and Sakata, M . , 1980, "On 2. Two new c r a c k i n i t i a t i o n l i f e p r e d i c t i o n meth- t h e Path Independent I n t e g r a l - J , " E n g i n e e r i n g F r a c t u r e ods have been developed for a p p l i c a t i o n t o complex Mechanics, Vol. 13, No. 4, pp. 841-850.

c r e e p - f a t i g u e l o a d i n g o f n o m i n a l l y i s o t r o p i c s u p e r a l - l o y s a h i g h t e m p e r a t u r e s .

Lindholm, U.S., Chan, K.S., Bodner, S . R . , Weber, R.M., Walker, K.P., and C a s s e n t i , B.N., 1984, 3. C y c l i c c o n s t i t u t i v e models f o r o x i d a t i o n pro- " C o n s t i t u t i v e M o d e l i n g for I s o t r o p i c M a t e r i a l s t e c t i v e c o a t i n g s and f o r h i g h l y a n i s o t r o p i c s i n g l e (HOST), " NASA CR-1747 18.

c r y s t a l t u r b i n e b l a d e a l l o y s have been developed and v e r i f i e d .

L i u , H . W . and Oshida, Y., 1986, " G r a i n Boundary O x i d a t i o n and F a t i g u e Crack Growth a t E l e v a t e d 4. A p r e l i m i n a r y c y c l i c c r a c k i n i t i a t i o n l i f e Temperatures." T h e o r e t i c a l and A p p l i e d F r a c t u r e p r e d i c t i o n model f o r c o a t e d s i n g l e c r y s t a l s u p e r a l - Mechanics, Vol. 6, No. 2, pp. 85-94.

l o y s has been proposed and i s u n d e r g o i n g c o n t i n u e d e v a l u a t i o n . The model u t i l i z e s t e n s i l e h y s t e r e t i c Manson, S.S., H a l f o r d , G.R., and N a c h t i g a l l , A.J., energy and f r e q u e n c y as p r i m a r y v a r i a b l e s .

1975, " S e p a r a t i o n o f t h e S t r a i n Components f o r Use i n S t r a i n r a n g e P a r t i t i o n i n g , " Advances i n Design f o r 5. Two h i g h t e m p e r a t u r e c y c l i c c r a c k g r o w t h l i f e E l e v a t e d Temperature Environment, S . Y . Zamrik and p r e d i c t i o n models have been proposed: micromechanis- R . I . J e t t e r , eds., ASME, New York, pp. 17-28.

t i c and phenomenological e n g i n e e r i n g approaches have been t a k e n . The m i c r o m e c h a n i s t i c approach i s based McGaw. M . A . and B a r t a l o t t a , P . A . , 1987, "A H i g h upon o x i d a t i o n i n t e r a c t i o n s w i t h mechanical deforma- Temperature F a t i g u e and S t r u c t u r e s T e s t i n g F a c i l i t y , " t i o n a t t h e c r a c k t i p , w h i l e t h e e n g i n e e r i n g approach 4 t h Annual H o s t i l e Environments and H i g h Temperature has i t s o r i g i n s i n t h e use o f Path-Independent I n t e - Measurements Conference Proceedings, S o c i e t y f o r g r a l s t o d e s c r i b e t h e necessary f r a c t u r e mechanics Experimental Mechanics, B e t h e l , CT, pp. 12-29. (See parameters.

a l s o , NASA TM-100151).

Moreno, V., 1983, "Creep F a t i g u e L i f e P r e d i c t i o n REFERENCES f o r Engine Hot S e c t i o n M a t e r i a l s ( I s o t r o p i c ) , " NASA CR-168228.

A i n s w o r t h , R . A . , Neale, B . K . , and P r i c e , R . H . , 1978, " F r a c t u r e Behavior i n t h e Presence o f Thermal Moreno, V . , N i s s l e y , D.M., and L i u , L.S., 1985, S t r a i n s , " Tolerance o f Flaws i n P r e s s u r i z e d Com- "Creep F a t i g u e L i f e P r e d i c t i o n for Engine Hot S e c t i o n ponents, I n s t i t u t i o n o f Mechanical Engineers, London, M a t e r i a l s ( I s o t r o p i c ) , " NASA CR-174844.

pp. 171-178.

R . H . , Dame, L . T . , and Moreno, V . , N i s s l e y , D.M., H a l f o r d , G . R . , and Ramaswamy, V.G., Van Stone, Saltsman, J.F., 1985, " A p p l i c a t i o n o f Two Creep- L a f l e n , J.H., 1985, " C o n s t i t u t i v e M o d e l i n g f o r F a t i g u e L i f e Models f o r t h e P r e d i c t i o n o f E l e v a t e d I s o t r o p i c M a t e r i a l s , " NASA CR-175004.

Temperature Crack I n i t i a t i o n o f a Nickel-Base A l l o y , " A I A A Paper 85-1420. Saltsman, J.F. and H a l f o r d , G . R . , 1988, "An Update o f t h e T o t a l S t r a i n V e r s i o n o f SRP," Low C y c l e Nelson, R . S . , Schoendorf, J . F . , and L i n , L.S., 1986, F a t i g u e - - D i r e c t i o n s for t h e f u t u r e , ASTM STP-942, ASTM, P h i l a d e l p h i a , P A , pp. 329-341.

"Creep F a t i g u e L i f e P r e d i c t i o n f o r Engine Hot S e c t i o n M a t e r i a l s ( I s o t r o p i c ) , " NASA CR-179550.

Swanson, G . A . , L i n a s k , I., N i s s l e y , D . M . , Norris, P.P., Meyer, T.G.. and Walker, K.P., 1987, Oshida, Y . and L i u , H.W., 1988, " G r a i n Boundary " L i f e P r e d i c t i o n and C o n s t i t u t i v e Models f o r Engine O x i d a t i o n and an A n a l y s i s o f t h e E f f e c t s o f O x i d a t i o n on F a t i g u e Crack N u c l e a t i o n L i f e , " Low C y c l e Fatigue-- Hot S e c t i o n A n i s o t r o p i c M a t e r i a l s , " NASA CR-179594.

D i r e c t i o n s f o r t h e F u t u r e , ASTM STP-942, ASTM, Tada, H . , P a r i s , P . C . , and I r w i n , G . R . , 1973, The P h i l a d e l p h i a , PA, pp. 1199-1217.

S t r e s s A n a l y s i s o f Cracks Handbook, Del Research C o r p o r a t i o n , H e l l e r t o w n , P A .

O s t e r g r e n , W.J., 1976, " A Damage F u n c t i o n and Asso- c i a t e d F a i l u r e Equations for P r e d i c t i n g H o l d Time and Walker, K . P . . 1981, "Research and Development Pro- Frequency E f f e c t s i n Elevated-Temperature, Low-Cycle grams f o r N o n l i n e a r S t r u c t u r a l Modeling w i t h Advanced f a t i g u e , " J o u r n a l o f T e s t i n g and E v a l u a t i o n , Vol. 4, Time-Temperature Dependent C o n s t i t u t i v e R e l a t i o n - NO. 5, pp. 327-339 s h i p s ," NASA CR-165533.

TABLE I. - HOST FATIGUE AND FRACTURE PROGRAMS

NAS3-23288, P r a t t & Whitney ( R . S . Nelson) Creep-Fatigue Crack I n i t i a t i o n - - I s o t r o p i c NAS3-23940, General E l e c t r i c ( J . J . L a f l e n ) E l e v a t e d Temperature Crack G r o w t h - - I s o t r o p i c NAS3-23939, P r a t t & Whitney ( G . A . Swanson) L i f e P r e d i c t i o n / C o n s t i t u t i v e M o d e l i n g - - A n i s o t r o p i c NAG3-348, Syracuse U n i v e r s i t y ( H . W . L i u ) Crack Growth Mechanisms--Isotropic Lewis ( M . A . McGaw) High-Temperature f a t i g u e and S t r u c t u r e s L a b o r a t o r y 0 OUT-OF-PHASE 0 IN-PHASE D c 6 L E G

I n HIGH TEPPERATURE A

I W 100 lo OOO k (A) BARE ALLOY.

-I CYCLIC I N I T I A T I O N L I F E - ACTUAL (B) COATED ALLOY.

FIGURE 1. - APPLICATION OF PRELIMINARY CDA M D E L TO RF L I F E PREDICTION FOR THE CAST NICKEL-BASE ALLOY, PWA 1455 (B1900 + H F ) , AFTER MORENO (1986).

LOG(Nf) FIGURE 2. - SCHERATIC REPRESENTATION OF TOTAL STRAIN- STRAINRANGE PART I T ION ING (TS-SRP) .

100 OOO- 0 1600 %. 0.5%, R = 0, 0.5 CPM (SERIES 1) 0 1600 OF, 0.5%. R = 0, TENS HOLD (SERIES 2 ) 0 1600 %. 0.75 KSI LOAD CONTROLLED (SERIES 3) A 1600 %. 0.75%. THEN 0.25-0.75%. 1 0 CPM (SERIES 4) d 1800 %. O.S%, R = 0 , 1 CPM (SERIES 5) 871 OC (1600 %I 983 OC (1800 %) 10 100 lo00 10 OOO ACTUAL LIFE. CYCLES FIGURE 3. - PREDICTION OF CW'LEX VERIFICATION EXPERI- E N T S USING TS-SRP, AFTER M E N O (1985).

0.25 CM THICK 650 OC 538 ' C 1.0 C M - SHIMOTO (1980) 1 2 3 4 5 INTEGRATION PATH NUWBER

FIGURE 4. - EVALUATION O F PATH-INDEPENDENT INTEGRALS UNDER

LlEAR TERERATURE GRADIENT I N SINGLE EDGE NOTCH SPECIFENS OF INCOWEL 718, AFTER K I M AND ORANGE (1988).

MATERIAL TWPERATURE, A K W A 6) WAVE-FORM

OC 0 INCOWEL 718 649 28 0 INCOIIEL x - 7 5 0 650 30 0 INCONEL x-750 650 30 A ASTROLOY 760 50 DATA A ASTROLOY 650 50 A ASTROLOY 700 10 0 304 S.S. 538 30

rn WASPALOY 649 30

V 1/2 CR-M-V STEEL 565 10 V 2 1/4 CR-16 STEEL 565 ;; 32 a .

G In 10-1

?

-32 A -36 A -160 OOO -1.40 -0.84 -0.28 0.28 0.84 1.40

I -

STRAIN, PERCENT V

10-4 F

V V FIGURE 6. - E X P E R I E N T A L LOOPS I N (001) AND (111) DIRECTIONS AT 871 C(1600 OF) AT STRAIN RATES OF: (A) 0.001% PER SECOND. (B) 0.0025% PER SECOND, (C) I I1111111 I I1111111 I I IIhl11 1 I1111111 I I IIlllrl I I I 1 0 - ~ 0.01% PER SECOND. (D) 0.1% PER SECOND. AND (E) 0.5% 10-4 10-3 10-2 10-1 100 io1 PER SECOND.

FREQUENCY. CYCLE/SEC FIGURE 5. - EVALUATION OF THE MlCROl+CHANISTIC OXIDATION CRACK EXTENSION M O D E L OF L I U AND OSHIDA (1986).

w.m L

-

I u) X

- """I

-

32 OOO ' u) a .

g 20

I- In f.4% 1 CPM -32 OOO OUT-OF-PHASE -20 ' -60 , -36 OOO -.6 -.4 -.2 0 .2 .4 .6 STRAIN. PERCENT

FIGURE 8. - OVERLAY COATING CONSTITUTIVE M O D E L PRE-

I I I I I

DICTION OF THERMAL E C H A N I C A L CYCLE AND C W A R I S O N -160 OOO 1.40 -1.40 -0.84 -0.28 0.28 0.84 WITH DATA.

STRAIN. PERCENT

FIGURE 7 . - MICRO ROODEL WITH BOTH OCTAHEDRAL AND CUBE

S L I P TERM CORRELATED TO (111) AND (001) DATA.

0 ISOTHERML LCF 427, 760, 927, 1038 OC (800, 1400, 1700. 1900?)

o w

427-1038 OR 427-1149 OC (800-1900 OR 800-2100 ?)

10 OOO- VARIOUS E-T CYCLES v) w -I V > V a 100 10 OOO ACTUAL LIFE, CYCLES FIGURE 9. - OVERLAY COATING L I F E R O E L CORRELATION OF OF ISOTHERML L I F E DATA AND PREDICTION OF THERMAL KCHANICAL FATIGUE L I F E DATA.

N09 20 1 4 3

L I F E MODELING OF THERMAL BARRIER COATINGS FOR AIRCRAFT GAS TURBINE ENGINES R. A. Miller National Aeronautics and Space Administration Lewis Rerearch Center Cleveland, Ohio C O A T I N G F A I L U R E M E C H A N I S M S A B S T R A C T A basic u n d e r s t a n d i n g of c o a t i n g f a i l u r e m e c h a n i s m s Thermal b a r r i e r c o a t i n g life m o d e l s developed i s a p r e r e q u i s i t e t o t h e d e v e l o p m e n t of life p r e d i c t i o n under t h e NASA Lewis R e s e a r c h Center's Hot S e c t i o n models. F a i l u r e m e c h a n i s m s in g a s turbine e n g i n e s a n d T e c h n o l o g y (HOST) p r o g r a m a r e summarized. A n initial in laboratory s i m u l a t i o n s have been discussed in detail laboratory model and t h r e e design-capable m o d e l s a r e discussed. C u r r e n t u n d e r s t a n d i n g of c o a t i n g f a i l u r e e l s e w h e r e (e.g., Miller, 1987; DeMasi e t al., 1988; m e c h a n i s m s a r e a l s o s u m m a r i z e d . S t r a n g m a n e t al., 1987, H i l l e r y e t al., 1987). T h e r e is n o w general a g r e e m e n t that t h e s e c o a t i n g s fail pri- I N T R O D U C T I O N marily a s a result of s t r e s s e s induced by t h e thermal e x p a n s i o n m i s m a t c h b e t w e e n the c e r a m i c a n d m e t a l l i c layers, and that t h e s e s t r e s s e s a r e g r e a t l y influenced Thermal b a r r i e r c o a t i n g s are being developed f o r in air- by time-at-temperature p r o c e s s e s such a s o x i d a t i o n and protecting air-cooled t u r b i n e blades a n d vanes craft g a s t u r b i n e engines. The c u r r e n t state-of-the-art p o s s i b l y s i n t e r i n g . The s t r e s s s t a t e in the c e r a m i c of a b o u t 0.25 mm of a zirconia- layer w h i c h leads t o c r a c k propagation and eventual c o a t i n g s y s t e m c o n s i s t s y t t r i a c e r a m i c o v e r 0.13 m m of an M C r A l Y alloy bond s p a l l i n g is o n e of biaxial c o m p r e s s i o n in the plane of t h e c o a t i n g a n d radial tension. T h e s e s t r e s s e s a r e f u r - coat. Both layers a r e a p p l i e d by plasma spraying. The benefits a r i s e f r o m t h e insulation provided by t h e t h e r c o m p l i c a t e d by t h e wavy and irregular i n t e r f a c e b e t w e e n the c e r a m i c and m e t a l l i c layers. In f a c t , c e r a m i c layer. T h i s i n s u l a t i o n a l l o w s higher g a s tem- p e r a t u r e s , lower c o m p o n e n t temperatures, r e d u c e d cool- HOST-sponsored c a l c u l a t i o n s indicate that the radial s t r e s s e s a b o v e a w a v y i n t e r f a c e may a c t u a l l y a l t e r n a t e ing a i r r e q u i r e m e n t s , m o d e r a t i o n o f thermal t r a n s i e n t s , T h i s between regions of c o m p r e s s i o n and tension as illus- a n d / o r a d e c r e a s e in t h e s e v e r i t y of hot spots.

t r a t e d i n Fig. 1 ( C h a n g e t al.. 1987). F i g u r e 2 y i e l d s i m p r o v e m e n t s in performance, e f f i c i e n c y , a n d com- ponent durability. F u t u r e e n g i n e d e s i g n s a r e e x p e c t e d i l l u s t r a t e s that t h e b e h a v i o r of plasma sprayed t o r e l y h e a v i l y o n thermal barrier coatings. T h u s life zirconia-based thermal b a r r i e r c o a t i n g s d i f f e r s signi f 1- m o d e l s a r e r e q u i r e d t o a s s e s s the risks a s s o c i a t e d w i t h c a n t l y f r o m t h e b e h a v i o r of conventional ceramics. T h i s behavior. which is believed t o result from the splat a n y g i v e n d e s i g n a n d t o insure that t h e s e c o a t i n g s c a n be e x p l o i t e d fully. F u r t h e r d e t a i l s m a y be f o u n d in structure, includes very low thermal c o n d u c t i v i t y and M i l l e r (1987), DeMasi e t al., (1988). S t r a n g m a n e t al., v e r y h i g h c o m p r e s s i v e s t r a i n tolerance. In-plane ten- (1987). a n d H i l l e r y (1987). sile strain t o l e r a n c e of t h e c o a t i n g s y s t e m is a l s o very T h e NASA thermal barrier coating life model devel- high because s u c h loading may lead t o segmentation in t h e c e r a m i c w i t h n o d e g r a d a t i o n t o the o p m e n t p r o g r a m c o n s i s t e d initially of a n in-house pro- c r a c k i n g g r a m d e s i g n e d t o i m p r o v e understanding and t o d e v e l o p a a t t a c h m e n t strength. P l a s m a sprayed zirconia-yttria model s u i t a b l e f o r t r e a t i n g laboratory life d a t a a l s o e x h i b i t s creep-like behavior, presumably a s a r e s u l t of s l i d i n g a t t h e s p l a t boundaries, and f a t i g u e - (Miller, 1987). T h i s w o r k was t h e n e x t e n d e d via t h r e e c o n t r a c t s u n d e r the H O S T program t o t h e d e v e l o p m e n t of like b e h a v i o r , presumably a s a r e s u l t of slow c r a c k design-capable m o d e l s (DeMasi e t al., 1988; S t r a n g m a n growth. Experimental e v i d e n c e of slow c r a c k growth (or e t al., 1987; H i l l e r y e t al., 1987). T h e s e c o n t r a c t s m i c r o c r a c k link up), creep, and f a t i g u e are presented w e r e devi sed d e t e r m i n e thermomechanical properties, t o in DeMasi e t al., (1988).

a n a l y z e c o a t i n g s t r e s s e s and strains, and t o d e v e l o p life models. P h a s e I of e a c h c o n t r a c t has n o w been suc- I N I T I A L L A B O R A T O R Y M O D E L D E V E L O P M E N T cessfully c o m p l e t e d , a n d t h e r e s u l t s will be summarized A p r e l i m i n a r y life prediction model has been in t h i s p a p e r .

described ( M i l l e r , 1987; Miller, 1984; M i l l e r e t al., 1984). T h i s model a s s u m e d that t h e complex s t a t e of

PRECEDING PAGE BLANK NOT FILMED

N f N i s t h e a p o a r e n t lumber of c y c l e s r e m a i n i n g s t r e s s and s t r a i n imposed on t h e c o a t i n g system by t h e h e r e a f t e r c y c l e U and w e i g h t g a i n 8 ~ .

thermal loads c o u l d be expressed i n terms o f a s i n g l e F i g u r e 4 i l l u s t r a t e s :he f i t s o b t a i n e d u s i n g

parameter. T h i s parameter was l a b e l l e d Cy -- which was

t a k e n t o be t h e r a d i a l component o f t h e thermal expan- i x p r e s s i o n 4 and a p p l y i n g ' t t o l i f e a a t a c o l l e c t e d a t i i 0 0 " C f o r t h r e e d i f f e r e n t c y c l e !erlqths. Tt should s i o n mismatch s t r a i n . Next i t was assumed t h a t t h e t i m e - a t - t e m p e r a t u r e e f f e c t s c o u l d be t r e a t e d i n terms 5e T e n t l o n e 0 t h a t t h e s e t af Parameters g i v e n i n t h e o f o x i d a t i o n a l o n e and t h a t o x i d a t i o n c o u l d be charac- f i g u r e a r e 7 o t u n i q u e . Yumerous o t n e r s e r s p r o v i d e t e r i z e d by t h e w e i g h t g a i n a t the c o n c l u s i o n o f eacn e q u a i l y gocd f i t s . For evamole r a i s i n g rhe assumed c y c l e W N . Then. w e i g h t g a i n and s t r a i n were r e i l t e d ' ~ a l u e c,f -7 m i l e l o w e r i n g t h e s t r a i n r a t i o aroduces u s i n g e i t h e r o f two a l t e r n a t e approaches. I n t h e f i r s t an e q u a l l y ;ood f i t . A l s o , t h e l i f e d a t a can be f i t case, d e p i c t e d i n F i g . 3 ( a ) . an o x i d i z e d c o a t i n g i s e q u a l l y w e i i J s i n g e x p r e s s i o n s 4 o r 5 .

assumed t o behave as i f an e f f e c t i v e s t r a i n Ee i s i n c r e a s i n g . A t z e r o w e i g h t g a i n t h i s e f f e c t i v e s t r a i n DESIGN-CAPASLE LIFE MODELING equals t h e r a d i a l s t r a i n c y . A t a c r i t i c a l w e i g h t g a i n w c -- d e f i n e d as t h e w e i g h t g a i n r e q u i r e d t o f a i l t h e v i h i i e t h e above model r e p r e s e n t e d a f i r s t s t e D i t c o a t i n g i n a s i n g l e c y c l e -- t h e e f f e c t i v e s t r a i n e q u a l s was n c t i n 3 f o r m which would be o f j s e t o an e n g i n e a f a i l u r e s t r a i n c f . T h i s leads t o t h e e x p r e s s i o n d e s i g n e r . - h e r e f o r e r h r e e c o n t r a c t s were i n s t i t u t e d under :he HOST program which were aimed a t t h e develop- ment o f Gesign-capable moaels.

P r a t t & Whitney A i r c r a f t (DeMasi e t a l . , 1 9 8 8 ) , a l o n g w i t h s u b c o n t r a c t o r Southwest Research I n s t i t u t e .

developed a f a t i g u e - b a s e d c o a t i n g l i f e model which ilses where t h e exponent m has been added t o a l l o w t h e c u r v e M i n e r ' s Law ( e p;ession 7 ) a l o n g - w i t h e x p r e s s i o n 6 i n F i g . 3(a) t o be n o n l i n e a r . The a l t e r n a t e assumption r e w r i t t e n as ( M i l l e r . 1987) i s t o assume t h a t t h e f a i l u r e s t r a i n degrades from an i n i t i a l v a l u e c f o t o a f i n a l v a l u e ( 8 ) equal t o E t . T h i s case, i l l u s t r a t e d i n F i g . 3 ( b ) leads t o t h e e x p r e s s i o n wnere A C i i s t h e i n e l a s t i c s t r a i n range d e f i n e d by ( 2 ) 2 0

A C = A ( a A T ) + Ach + A c t -

( 9 ) E The t e r m A(a A T ) i n t h e above e x p r e s s i o n i s t h e t h e r - Cracks i n t h e ceramic l a y e r may be assumed t o grow a c c o r d i n g t o a c r a c k growth law o f t h e f o r m mal expansion mismatch s t r a i n ( w h i c h was expressed i n t e r m s o f Cy i n t h e p r e v i o u s s e c t i o n ) , Ach i s t h e dA s t r a i n r e s u l t i n g f r o m t h e h e a t i n g t r a n s i e n t , hC i s - dN = Aeebac ( 3 ) ti:e i t r a i n r e s u l t i n g f r o m t h e c o o l i n g t r a n s i e n t , and o,,,/E i s t h e e l a s t i c s t r a i n a t y i e l d i n g . The assumed rC1 a t i o n s h i p between o x i d a t i o n and s t r a i n , analogous t o where da/dN i s t h e i n c r e m e n t a l c r a c k growth p e r c y c l e , A i s a c o n s t a n t , b and c a r e exponents r e l a t e d to e x p r e s s i o n 2 . was I , .d t h e s u b c r i t i c a l c r a c k growth exponent. and a i s t h e c r a c k l e n g t h . The model r e s u l t i n g from e x p r e s s i o n 1 i s (10) N , where o x i d a t i o n has been expressed i n terms o f t h e o x i d e l a y e r t h i c k n e s s 6 r a t h e r t h a n t h e s p e c i f i c h e i g h t g a i n w . The i n e l a s t i c s t r a i n range was c a l c u - l a t e d u s i n g f i n i t e element t e c h n i q u e s Nhich employed a t i m e dependent i n e l a s t i c model developed by N a l k e r ( 1 9 8 3 ) . F i g u r e 5 shows an example o f t h e use of t h i s and t h e a l t e r n a t i v e model r e s u l t i n g f r o m e x p r e s s i o n 2 i s model t o c a l c u l a t e compressive and t e n s i l e s t r a i n s which may be compared d i t h e x p e r i m e n t a l d a t a . I n F i g . 6 t h e N , ceramic s t r e s s - s t r a i n b e h a v i o r i s c a l c u l a t e d f o r a s i n - g l e c y c l e . T h i s f i g u r e d i s p l a y s t h e l a r g e amount o f r e v e r s e d i n e l a s t i c s t r a i n produced by thermal c y c l i n g .

F i g u r e 7 shows a p l o t o f observed versus c a l c u l a t e d l i v e s f o r a wide range o f t e s t c o n d i t i o n s . As shown i n t h e f i g u r e t h e model i s a c c u r a t e t o p l u s o r minus a f a c - t o r o f 3, which i s c o n s i d e r e d adequate. These models may a l s o be d e r i v e d f r o m t h e f a m i l i a r The model developed by t h e G a r r e t t T u r b i n e Engine f a t i g u e e x p r e s s i o n ( M i l l e r e t a l . . 1984; Manson, 1966).

Company (Strangman e t a l . , 1987) may be expressed as -b ( 6 )

Nf = ( : )

and M i n e r ' s Law ( 7 ) N = l E q u a t i o n 1 1 i s expressed s c h e m a t i c a l l y i n F i g . 8 which s h e a r i n g s t r e s s e s , i n c l u d i n g t h e r o l e t h a t s h e a r i n g a t shows t h a t t h e mode1 c o n s i d e r s bond c o a t o x i d a t i o n , z i r - an edge may p l a y i n r e d u c i n g t h e f a t i g u e exponent, i s c o n i a toughness r e d u c t i o n , and damage due t o m o l t e n s a l t n o t w e l l u n d e r s t o o d . The d e t a i l e d mechanism by which d e p o s i t s . The model i s d r i v e n by t h e thermal a n a l y s i s o x i d a t i o n c o n t r o l s c o a t i n g system l i f e i s n o t w e l l of t h e component of i n t e r e s t f o r i t s a n t i c i p a t e d m i s - understood e i t h e r . Also, i t i s n o t known whether t h e Zion. The l e f t s i d e o f t h e denominator i n e x p r e s s i o n 1 1 assumption o f a smooth i n t e r f a c e , commonly employed to as d e t e r m i n e d from t e s t d a t a c a l i b r a t i o n s i s s i m p l i f y f i n i t e element a n a l y s e s can l e a d t o i n a c c u r a t e o r even m i s l e a d i n g r e s u l t s . O t h e r areas o f u n c e r t a i n t y i n v o l v e t h e importance o f s i n t e r i n g a t h i g h temperatures ltO"' + 0.181) MTBREF and h o t c o r r o s i o n a t r e l a t i v e l y low t e m p e r a t u r e s .

- I [exp[-0.015(1 + 273) + C l l ) - ' + (exp[-0.041( +273) + C , ] ) REFERENCES ( 1 2 ) Chang, G . C . , Phucharoen, W . , and M i l l e r , R . A . , 1987.

where MTBREF i s a m u l t i t e m p e r a t u r e b u r n e r r i g e x p e r i - B e h a v i o r o f Thermal B a r r i e r C o a t i n g s f o r Advanced Gas ence f a c t o r which f o r c e s p r e d i c t i o n s and e x p e r i m e n t i n t o T u r b i n e B l a d e s , " S u r f a c e and C o a t i n g s Technology, agreement. The r i g h t s i d e o f t h e denominator i n expres- V O l . 30, pp. 13-28.

s i o n 1 1 i s c a l c u l a t e d u s i n g a G a r r e t t - d e v e l o p e d model (Strangman, 1984; Strangman e t a l . , 1987). I n p r a c t i c e , DeMasi, J . T . , O r t i z , M., and S h e f f l e r , K.D..1988, "Ther- t h e model i s d r i v e n by t h e r m a l a n a l y s i s of t h e component mal B a r r i e r C o a t i n g L i f e P r e d i c t i o n Model Development", o f i n t e r e s t .

An example o f t h e a p p l i c a t i o n o f t h e t h e r - NASA C o n t r a c t o r Report, t o be p u b l i s h e d ( P r a t t & N h i t - mal b a r r i e r c o a t i n g l i f e model t o l a b o r a t o r y t e s t d a t a ney A i r c r a f t ) i s shown i n F i g . 9, and m i s s i o n a n a l y s i s p r e d i c t i o n s a r e 10.

shown i n F i g .

H i l l e r y , R . V . , P i l s n e r , B.H., McKnight, R.L., Cook, T .

The approach used b y t h e General E l e c t r i c Company S . , and H a r t l e . M. S., 1987, "Thermal B a r r i e r C o a t i n g ( H i l l e r y e t a l . , 1987) employed time-dependent, n o n l i n - NASA CR-180807.

L i f e P r e d i c t i o n Model, F l n a l R e p o r t , " e a r f i n i t e element m o d e l i n g of t h e s t r e s s e s and s t r a i n s p r e s e n t i n t h e t h e r m a l b a r r i e r c o a t i n g system, f o l l o w e d Manson, S . S . , 1966, "Thermal S t r e s s and Low C y c l e by t h e c o r r e l a t i o n o f t h e s e s t r e s s e s and s t r a i n s w i t h F a t i g u e , " McGraM-Hill Book Company, New York, 1966.

t e s t l i v e s . The l i f e model developed u s i n g t h i s approach may be expressed as M i l l e r , R . A . , 1984. "Oxidation-Based Thermal B a r r i e r C o a t i n g L i f e P r e d i c t i o n Model" J o u r n a l o f t h e American

A E ~ ~ + 0 . 4 AcR = 0.121 Nf -0.486

( 1 3 ) Ceramic Science, Vol. 67, No. 8. pp. 517-521.

M i l l e r , R . A . , Agarwal, P . , and D u d e r s t a d t , E . C . , 1984, where A E R Z i s t h e shear s t r a i n range, AER i s t h e n o r - L i f e M o d e i i n g o f Atmospheric and Low P r e s s u r e Plasma mal s t r a i n range, and Nf i s t h e number o f c y c l e s t o Sprayed Thermal B a r r i e r C o a t i n g , " Ceramic E n g i n e e r i n g f a i l u r e . The above model i s t h e o n l y one t o c o n s i d e r Science Procedings, Vol 5 . No. 7-8, pp. 470-478.

f a i l u r e induced by edges and hence i s t h e o n l y one t o c o n s i d e r shear s t r a i n . E x p r e s s i o n 13 i s i l l u s t r a t e d M i l l e r , R . A . , 1987, " C u r r e n t S t a t u s o f Thermal B a r r i e r g r a p h i c a l l y i n F i g . 1 1

C o a t i n g s - An Overview," S u r f a c e and C o a t i n g s Technolo-

gy, V O l . 30, NO. 1 , pp. 1 - 1 1 .

CONCLUDING REMARKS Strangman, T . E . , 1984. " L i f e P r e d i c t i o n and Development I n c o n c l u s i o n , t h e m a t e r i a l s and s t r u c t u r a l aspects of C o a t i n g s for T u r b i n e A i r f o i l s . " Workshop o n Gas Tur- o f t h e r m a l b a r r i e r c o a t i n g s have been s u c c e s s f u l l y i n t e - b i n e M a t e r i a l s i n a M a r i n e Environment, Bath, U. K .

g r a t e d under t h e NASA HOST program t o produce models which may now or i n t h e n e a r f u t u r e be used i n d e s i g n .

Strangman. T . E . , Neumann, J . , and L i u , A . , 1987, "Ther- E f f o r t s on t h i s program c o n t i n u e a t P r a t t & Whitney A i r - mal B a r r i e r C o a t i n g L i f e P r e d i c t i o n Model Development, c r a f t where t h e i r model i s b e i n g extended t o t h e l i f e F i n a l Report," NASA CR-179648.

p r e d i c t i o n o f p h y s i c a l vapor d e p o s i t e d thermal b a r r i e r c o a t i n g s .

K , P . , 1983, "Research and Development Program Walker, While t h e HOST program has been q u i t e successful i t f o r Non-Linear S t r u c t u r a l M o d e l i n g w i t h Advanced Time- s h o u l d a l s o be n o t e d t h a t many new and unanswered ques- Temperature Dependent C o n s t i t u i t i v e R e l a t i o n s h i p s , " t i o n s have been r a i s e d by t h i s work. For example, t h e NASA CR-165533.

o f c r e e p and i n e l a s t i c i t y i n b o t h t h e ceramic e f f e c t s and bond c o a t l a y e r s a r e p o o r l y understood. The role o f C E R M I C /- 01 = 0 BOND COAT FIGURE 1. - SCHEMATIC REPRESENTATIUN OF CALCULATED RADIAL THERML EXPANSION MISR4TCH STRESS ABOVE A WAVY INTER- FACE.

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FIGURE 5. - CERMIC BEHAVIOR MODELED WITH WALKER EQUATION

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N89-20144

VIEWS ON THE IMPACT OF HOST J. 8. €war Sverdrup Technology, Inc.

Lewis Research Center Cleveland. Ohio D. E. Sokolowrki National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio ABSTRACT p a r t i c i p a n t s , p r i m a r i l y from i n d u s t r y and academia, t o d e t e r m i n e t h e i r v i e w p o i n t s . T h i s paper summarizes r e s u l t s from t h e i n t e r v i e w s .

The Hot S e c t i o n Technology (HOST) P r o j e c t , which was i n i t i a t e d b y NASA Lewis Research C e n t e r i n 1980 INTRODUCTION and concluded i n 1987. was aimed a t i m p r o v i n g advanced a i r c r a f t e n g i n e h o t s e c t i o n d u r a b i l i t y t h r o u g h b e t t e r The Hot S e c t i o n Technology P r o j e c t , which has t h e t e c h n i c a l u n d e r s t a n d i n g and more a c c u r a t e d e s i g n a n a l y - acronym HOST, was i n i t i a t e d by NASA Lewis Research Cen- s i s c a p a b i l i t y . The p r o j e c t was a m u l t i d i s c i p l i n a r y , t e r i n t h e F a l l o f 1980 t o address t h e need f o r improv- m u l t i o r g a n i z a t i o n a l , focused r e s e a r c h e f f o r t t h a t i n g d u r a b i l i t y o f advanced a i r c r a f t t u r b i n e engines.

i n v o l v e d 21 o r g a n i z a t i o n s and 70 r e s e a r c h and t e c h n o l - Near t h e c o n c l u s i o n o f t h e p r o j e c t i n t h e F a l l o f 1987 ogy a c t i v i t i e s and g e n e r a t e d a p p r o x i m a t e l y 250 r e s e a r c h a s u r v e y of knowledgeable p a r t i c i p a n t s was conducted r e p o r t s . N o m a j o r hardware was developed. To e v a l u - t o assess t h e impact and v a l u e o f HOST t o i n d u s t r y , t o a t e whether HOST had a s i g n i f i c a n t impact on t h e o v e r - academia, and t o t h e government. T h i s paper summarizes a l l a i r c r a f t e n g i n e i n d u s t r y i n t h e development o f new t h e r e s u l t s o f t h e survey.

engines, i n t e r v i e w s were conducted w i t h 41 p a r t i c i p a n t s The HOST P r o j e c t was unique i n s e v e r a l ways. I t s i n t h e p r o j e c t t o o b t a i n t h e i r v i e w s . The summarized f o c u s on d u r a b i l i t y was i n c o n t r a s t t o o t h e r r e c e n t r e s u l t s of these i n t e r v i e w s a r e p r e s e n t e d .

NASA-sponsored programs t h a t focused p r i m a r i l y on p e r - formance improvements. Those programs i n c l u d e d t h e SUMMARY Energy E f f i c i e n t Engine ( E E E ) , Engine Component Improvement (ECI), and Advanced Turboprop Program The NASA-sponsored HOST P r o j e c t addressed d u r a b i l - (ATP) and i n v o l v e d o n l y a p o r t i o n o f t h e a i r c r a f t i t y needs i n advanced a i r c r a f t e n g i n e combustors and The HOST P r o j e c t complemented such t u r b i n e s by d e v e l o p i n g improved methods for d e s i g n e n g i n e i n d u s t r y .

programs on performance improvement, which o f t e n t e n d a n a l y s i s and l i f e p r e d i c t i o n o f c r i t i c a l p a r t s . Pro- t o a g g r a v a t e engine hardware d u r a b i l i t y . I n a d d i t i o n v i d i n g t e c h n o l o g y t o improve engine d u r a b i l i t y should, i n t u r n , reduce maintenance c o s t s and improve f l i g h t t h e 70 m a j o r r e s e a r c h and t e c h n o l o g y a c t i v i t i e s i n i t i - a t e d under HOST drew on r e s e a r c h e r s from t h r e e work s a f e t y . Because o f t h e n a t u r e o f c h a l l e n g e s i n deve- s e c t o r s - - i n d u s t r y ( i n c l u d i n g a l l t h e l a r g e U . S . e n g i n e l o p i n g d u r a b l e s t r u c t u r e s , t h e p r o j e c t was m u l t i d i s c l - m a n u f a c t u r e r s ) , academia, and government--to work p l i n a r y and m u l t i o r g a n i z a t i o n a l i n v o l v i n g 70 r e s e a r c h j o i n t l y toward common g o a l s .

and t e c h n o l o g y a c t i v l t i e s . While most p r o j e c t s r e s u l t Another unique f e a t u r e o f HOST was i t s f o c u s e d i n a d e l i v e r a b l e p i e c e o f m a j o r hardware, t h e HOST P r o j e c t i n s t e a d g e n e r a t e d a p p r o x i m a t e l y 250 r e s e a r c h and i n t e g r a t e d r e s e a r c h encompassing s i x e n g i n e e r i n g r e p o r t s t h a t c o v e r r e s u l t s from a n a l y t i c a l modeling. d i s c i p l i n e s t h a t addressed c r i t i c a l t e c h n o l o g y needs i n t h e e n g i n e h o t s e c t i o n - - t h e combustor and t u r b i n e h i g h l y c o n t r o l l e d s m a l l - s c a l e experiments, and numer- components. The d i s c i p l i n e s a r e i n s t r u m e n t a t i o n , com- ous computer codes t h a t were developed. HOST Annual Workshops b r o u g h t t o g e t h e r r e p r e s e n t a t i v e s f r o m a1 1 b u s t i o n , t u r b i n e h e a t t r a n s f e r , s t r u c t u r a l a n a l y s i s , m a j o r U.S. gas t u r b i n e m a n u f a c t u r e r s and f r o m a s i g n i f - f a t i g u e and f r a c t u r e , and s u r f a c e p r o t e c t i o n . HOST a c t e d as a k e y s t o n e t h a t h e l p e d b r i d g e t h e gap between i c a n t number of u n i v e r s i t i e s and r e s e a r c h i n s t i t u t e s i n an e f f e c t i v e f o r u m t o d i s c u s s and c r i t i q u e r e c e n t these sometimes d i v e r s e groups and p r o v i d e d mutual sup- work t o g e t h e r .

r e s e a r c h f i n d i n g s . To b e t t e r u n d e r s t a n d t h e impact o f p o r t i n h e l p i n g them While t h e program was j u s t i f i e d f o r c i v i l a i r - t h e HOST P r o j e c t , i t s c o s t e f f e c t i v e n e s s , and b e n e f i t s d e r i v e d by o r g a n i z a t i o n s h a v i n g a s s o c i a t i o n w i t h it, c r a f t needs, m i l i f a r y needs were e q u a l l y s a t i s f i e d numerous i n t e r v i e w s were conducted w i t h key program because t h e same 'design a n a l y s i s systems a r e used by m a n u f a c t u r e r s i n d e v e l o p i n g b o t h c i v i l and m i l i t a r y A p p r o x i m a t e l y 90 p e r c e n t o f t h e i n t e r v i e w s were e n g i n e s . conducted i n person, w i t h t h e remainder conducted by F i n a l l y , no m a j o r hardware, such as an engine pro- t e l e p h o n e . A t o t a l o f 41 i n t e r v i e w s were conducted t o t y p e , was developed. I n s t e a d t e c h n i c a l understand- w i t h t h e f o l l o w i n g breakdown by o r g a n i z a t i o n : 2 6 f r o m i n g and d e s i g n a n a l y s i s c a p a b i l i t y were improved and e n g i n e m a n u f a c t u r e r s , 5 from u n i v e r s i t i e s , 4 f r o m documented i n a p p r o x i m a t e l y 250 p u b l i s h e d r e s e a r c h r e s e a r c h i n s t i t u t i o n s , and 6 from government (NASA and U . S . A i r F o r c e ) . Personal i n t e r v i e w s were conducted r e p o r t s and i n numerous computer codes t h a t were deve- w i t h key p a r t i c i p a n t s from t h e f o u r major a i r c r a f t l o p e d . Technology was f u r t h e r i d e n t i f i e d and t r a n s - f e r r e d i n a t i m e l y manner t h r o u g h s i x m a j o r annual e n g i n e m a n u f a c t u r e r s i n t h e program, namely P r a t t and workshops, which had a t o t a l a t t e n d a n c e o f 1500 peo- Whitney, General E l e c t r i c Company, A l l i s o n Gas T u r b i n e D i v i s i o n o f General Motors C o r p o r a t i o n , and G a r r e t t p l e . U s i n g t h e r e s e a r c h p r e s e n t e d i n t h e r e p o r t s and t o change develop- first a t t h e workshops, a move was s t a r t e d T u r b i n e Engine Company. The approach was t o ment o f advanced engines from t h e h i s t o r i c a l experimen- c a l l t h e o r g a n i z a t i o n and t e l l them t h e s u b j e c t t o be o f " b u i l d 'em and b u s t 'em" t o a t a l t e s t i n g approach d i s c u s s e d . V i s i t s t h e n were made and those i n t e r v i e w e d were g i v e n t h e o p p o r t u n i t y t o s t a t e t h e i r views on b o t h more a n a l y t i c a l approach i n which component hardware d e s i g n s a r e analyzed w i t h much more a c c u r a t e d a t a bases p o s i t i v e and n e g a t i v e aspects o f t h e p r o j e c t . E f f o r t s and m a t h e m a t i c a l models b e f o r e t e s t i n g i s begun. Test- were made t o s o l i c i t i n d i v i d u a l views, e i t h e r p r o or i n g i s t h e n more for d e s i g n v e r i f i c a t i o n t h a n f o r con, and t o a v o i d q u e s t i o n s or comments s e e k i n g p r a i s e for t h e program. No s e t q u e s t i o n s were asked i n t h e e x p e r i m e n t a l development.

A t o t a l o f 40 s e p a r a t e a c t i v i t i e s were competi- i n t e r v i e w s . I n s t e a d , i n d i v i d u a l s were asked a few gen- e r a l t i v e l y c o n t r a c t e d w i t h a i r c r a f t engine m a n u f a c t u r e r s q u e s t i o n s and t h e n g i v e n t h e o p p o r t u n i t y t o express whatever o p i n i o n s t h e y had. A c t i v e l i s t e n i n g and r e s e a r c h i n s t i t u t e s p l u s 13 g r a n t s t o u n i v e r s i - t i e s . Seventeen m a j o r a c t i v i t i e s were s u p p o r t e d a t was used t o encourage d i s c u s s i o n and t o a v o i d g u i d i n g NASA Lewis Research C e n t e r . A t o t a l o f 21 o r g a n i - I f t h e r e were q u e s t i o n s c o n c e r n i n g t h e i n t e r - t h e answers.

z a t i o n s were r e p r e s e n t e d i n t h e e f f o r t . I n a d d i t i o n p r e t a t i o n o f comments g i v e n , f o l l o w - u p telephone c a l l s t o t h e above mentioned u n i v e r s i t y g r a n t s , s e v e r a l manu- were made for c l a r i f i c a t i o n . I n s e v e r a l cases t h e f a c t u r e r s s u b c o n t r a c t e d p a r t s o f t h e i r work t o u n i v e r - i n t e r v i e w e r ' s w r i t t e n summary o f comments was s e n t t o s i t y r e s e a r c h e r s , who may or may n o t a l s o have had t h e o r g a n i z a t i o n s i n t e r v i e w e d t o d e t e r m i n e i f t h e i n d i - d i r e c t NASA HOST g r a n t s . The 40 c o n t r a c t s were gener- v i d u a l s c o n c u r r e d w i t h t h e i n t e r v i e w e r ' s i n t e r p r e t a - a l l y m u l t i y e a r and o f t e n m u l t i p h a s e d . t i o n . I t i s t h e b e l i e f o f t h e i n t e r v i e w i n g a u t h o r T h i s approach p r o v i d e d a g r e a t e r o p p o r t u n i t y f o r i n t e r a c t i o n between t h a t t h e a p p r a i s a l s g i v e n were spontaneous and hon- v a r i o u s o r g a n i z a t i o n s r e p r e s e n t e d t h a n i s n o r m a l l y e s t . T h i s r e p o r t does n o t i d e n t i f y i n d i v i d u a l s or encountered i n government s h o r t - t e r m c o n t r a c t e d o r g a n i z a t i o n s o t h e r t h a n l i s t i n g t h e f o u r e n g i n e manu- e f f o r t s . f a c t u r e r s and t h e government o r g a n i z a t i o n s from whom To e v a l u a t e and r e p o r t t h e impact o f t h e HOST comments were s o l i c i t e d .

P r o j e c t , 41 i n d i v i d u a l s f r o m p a r t i c i p a t i n g o r g a n i z a - t i o n s were i n t e r v i e w e d . These i n t e r v i e w s , p l u s some F I N D 1 NGS r e s u l t s from a 1984 m i d - p r o j e c t assessment t h a t a l s o i n v o l v e d i n d u s t r y and academia p a r t i c i p a n t s , a r e sum- There was unanimous agreement from everyone i n t e r - m a r i z e d i n t h i s paper t o p r o v i d e w r i t t e n t e s t i m o n y on viewed t h a t t h e HOST P r o j e c t was h i g h l y e f f e c t i v e and t h e HOST P r o j e c t . f u r t h e r , t h e f i n d i n g s may p r o v i d e to t h e mutual b e n e f i t o f a l l p a r t i c i p a n t s . NASA was guidance i n p l a n n i n g f u t u r e government-sponsored l a u d e d for t h e c o n c e p t i o n , advocacy, and management o f r e s e a r c h programs. t h e program.

There was agreement t h a t w i t h o u t HOST many o f t h e i m p o r t a n t r e s e a r c h programs, which a r e APPROACH needed t o advance t e c h n o l o g y i n t h e h o t s e c t i o n of gas t u r b i n e engines, would have been d e l a y e d for y e a r s o r never u n d e r t a k e n .

The g o a l o f t h i s s t u d y was t o d e t e r m i n e t h e HOST Elements o f HOST which were p a r t i c u - l a r l y emphasized as b e i n g b e n e f i c i a l by a number o f P r o j e c t ' s impact by o b t a i n i n g views from a r e p r e s e n t a - t i v e number o f key p a r t i c i p a n t s . E f f o r t s were made t o t h o s e i n t e r v i e w e d i n c l u d e d : ( 1 ) t h r e e - d i m e n s i o n a l a v o i d b i a s e s , i f any, o f t h e i n t e r v i e w e r . The a u t h o r s i n e l a s t i c s t r u c t u r a l a n a l y s i s , ( 2 ) thermomechanical o f t h i s paper i n c l u d e t h e NASA manager o f t h e HOST f a t i g u e t e s t i n g , ( 3 ) c o n s t i t u t i v e modeling, ( 4 ) com- b u s t o r a e r o t h e r m a l modeling, (5) t u r b i n e h e a t t r a n s - P r o j e c t , who conceived and g u i d e d t h e study, and a sup- p o r t s e r v i c e c o n t r a c t o r , who conducted t h e s t u d y and f e r , and ( 6 ) p r o t e c t i v e c o a t i n g s . I n s t r u m e n t a t i o n r e s e a r c h was a l s o emphasized as b e i n g b e n e f i c i a l , p r i - who had c o n s i d e r a b l e a i r b r e a t h i n g engine background p r i o r t o t h i s p r o j e c t . The s u p p o r t s e r v i c e c o n t r a c t o r m a r i l y by t h e s i n g l e o r g a n i z a t i o n c o n d u c t i n g t h a t had n o p r i o r knowledge o f t h e HOST P r o j e c t and e n t e r e d r e s e a r c h . O t h e r o r g a n i z a t i o n s were l e s s e n t h u s i a s t i c because t h e developed i n s t r u m e n t a t i o n was n o t commer- t h e s t u d y w i t h no b i a s e s r e g a r d i n g HOST. The p r o j e c t c i a l l y a v a i l a b l e t o them. I n a somewhat s i m i l a r man- manager made s u g g e s t i o n s as to a p p r o p r i a t e HOST p a r t i c - i p a t i n g o r g a n i z a t i o n s and p e o p l e t o c o n t a c t . The n e r computer codes developed i n t h e HOST P r o j e c t were c o n t r a c t o r c o n t a c t e d t h e s e o r g a n i z a t i o n s , made arrange- g e n e r a l l y more u s e f u l t o t h e o r g a n i z a t i o n d e v e l o p i n g t h e codes t h a n t o o t h e r s , p a r t i c u l a r l y for t h e l o n g e r , ments f o r v i s i t s , and conducted i n t e r v i e w s b o t h w i t h p e o p l e suggested by t h e p r o j e c t manager and w i t h o t h e r s more complex codes.

suggested by some o f t h o s e i n t e r v i e w e d . Throughout Two areas, t h a t were n o t r e s e a r c h i n n a t u r e , t h e d u r a t i o n o f t h e i n t e r v i e w p e r i o d some HOST p a r t i c i - r e c e i v e d near unanimous a p p r o v a l . The f i r s t was t h e p a n t s c a l l e d and v o l u n t e e r e d u n s o l i c i t e d comments. By annual workshops where c u r r e n t r e s e a r c h r e s u l t s were means o f t h i s approach t h e co-author most f a m i l i a r p r e s e n t e d and d i s c u s s e d , and t h e second was t h e w i t h t h e p r o j e c t p r o v i d e d l e a d s o f o r g a n i z a t i o n s a n d / o r improved i n d u s t r y - u n i v e r s i t y - N A S A r e l a t i o n s h i p s .

personnel who had been a c t i v e i n t h e o v e r a l l program, D i s c u s s i o n o f comments r e c e i v e d on t h e above men- and t h e o t h e r a u t h o r conducted t h e i n t e r v i e w s and gath- t i o n e d areas p l u s o t h e r b e n e f i t s o r comments for e r e d d a t a p r e s e n t e d h e r e i n w i t h o u t p r e c o n c e i v e d i d e a s improvement f o l l o w .

on t h e impact of HOST.

Impact on T e c h n i c a l U n d e r s t a n d i n g and P r e d i c t i v e C o n s t i t u t i v e modelinq. C o n s t i t u t i v e modeling i s C a p a b i l i t y an a n a l y t i c a l approach f o r p r e d i c t i n g s t r e s s e s and o f t i m e under complex c y c l i c s t r a i n s as a f u n c t i o n Three-dimensional i n e l a s t i c s t r u c t u r a l a n a l y s i s .

b i a x i a l mechanical l o a d i n g and t e m p e r a t u r e v a r i a t i o n s .

I n e l a s t i c o r n o n l i n e a r s t r u c t u r a l analvses have l i m - i s based on e x p e r i m e n t a l thermomechanical The modeling i t e d , b u t v e r y i m p o r t a n t , a p p l i c a t i o n s : These analyses d e f o r m a t i o n d a t a . Prior t o t h e HOST P r o j e c t r e s e a r c h a r e used p r i m a r i l y f o r s h o r t - l i f e c y c l i c a p p l i c a t i o n s on c o n s t i t u t i v e m o d e l i n g was done p r i m a r i l y a t u n i v e r - where i t may be a c c e p t a b l e t o exceed t h e e l a s t i c l i m i t s i t i e s , and n o t a t a i r c r a f t e n g i n e m a n u f a c t u r e r s . HOST f o r a f e w c y c l e s . For l o n g - l i f e a p p l i c a t i o n s , however, p r o v i d e d a team approach o f i n d u s t r y , u n i v e r s i t i e s , hardware g e n e r a l l y s h o u l d be designed for o p e r a t i o n and NASA w o r k i n g t o g e t h e r t o develop a c a p a b i l i t y t h a t w i t h i n t h e e l a s t i c r a n g e . B u t even f o r l o n g - l i f e d i d n o t e x i s t p r e v i o u s l y . The aerospace i n d u s t r y now a p p l i c a t i o n s based on e l a s t i c d e s i g n , t h e r e a r e occa- has t h e c a p a b i l i t y t o use n o n l i n e a r c o n s t i t u t i v e models s i o n s when t h r e e - d i m e n s i o n a l (3-D) i n e l a s t i c a n a l y s i s of b o t h i s o t r o p i c and a n i s o t r o p i c m e t a l l i c m a t e r i a l s may be needed. One o c c a s i o n i s when a s h o r t e r t h a n i n i n e l a s t i c s t r u c t u r a l a n a l y s i s . T h i s r e s e a r c h has p r e d i c t e d l i f e i s encountered. I n t h i s case an i n e l a s - t o f u r t h e r e x t e n d c o n s t i t u t i v e model- p r o v i d e d a base t i c a n a l y s i s can o f t e n p i n p o i n t t h e p r o b l e m a r e a . I n i n g t o more complex m a t e r i a l s such as metal m a t r i c e s .

a d d i t i o n a 3-D i n e l a s t i c a n a l y s i s can be u s e f u l f o r A s a r e s u l t o f t h e HOST P r o j e c t NASA Lewis Research d e t e r m i n i n g s t r e s s r e d i s t r i b u t i o n when l o c a l y i e l d i n g Center has become an i m p o r t a n t c e n t e r , worldwide, for o c c u r s . Thus f o r such s p e c i a l cases, 3-D i n e l a s t i c c o n s t i t u t i v e modeling.

HOST has n o t o n l y i n t r o d u c e d a n a l y s i s can be a v e r y i m p o r t a n t d e s i g n t o o l .

c o n s t i t u t i v e modeling t o e n g i n e companies, i t has True t h r e e - d i m e n s i o n a l a n a l y t i c a l methods have r e s u l t e d i n a c l o s e r w o r k i n g r e l a t i o n s h i p between them o n l y become a v a i l a b l e t o e n g i n e d e s i g n a n a l y s t s w i t h i n and academia.

t h e l a s t f e w y e a r s - - a f t e r t h e HOST P r o j e c t was i n i t i - a t e d . Several approaches t o 3-D i n e l a s t i c a n a l y s i s Combustor a e r o t h e r m a l modeling. Research had been were pursued i n t h e p r o j e c t . The b e s t approach may conducted p r i o r to HOST on combustor m o d e l i n g aimed a t n o t be known for some t i m e . C u r r e n t l y 3-D i n e l a s t i c p r e d i c t i n g d i l u t i o n j e t a i r f l o w m i x i n g w i t h combustion d e s i g n a n a l y s e s a r e cumbersome, c o m p l i c a t e d , and gases. Those m o d e l i n g s t u d i e s were based on b u l k aver- r e q u i r e a g r e a t deal o f computer t i m e . Consequently age t e m p e r a t u r e measurements from j e t m i x i n g e x p e r i - t h e r e i s some r e l u c t a n c e on t h e p a r t o f a n a l y s t s t o ments. Such r e s e a r c h had g r e a t l y d i m i n i s h e d by t h e use 3-D i n e l a s t i c a n a l y s i s u n l e s s a b s o l u t e l y neces- t i m e o f HOST i n i t i a t i o n . I n t h e HOST P r o j e c t a l l f o u r s a r y . W i t h t i m e , however, as d e s i g n a n a l y s t s become engine m a n u f a c t u r i n g companies were awarded c o n t r a c t s more c o m f o r t a b l e w i t h t h i s a n a l y s i s approach, i t t o assess t h e s t a t e o f t h e a r t i n combustor a e r o t h e r - s h o u l d be used more e x t e n s i v e l y .

I t s use i s b o t h for mal modeling. As a r e s u l t o f t h i s assessment and a d d i - problems t h a t o c c u r e a r l y d u r i n g e n g i n e development t i o n a l r e s e a r c h w i t h n o n r e a c t i n g flows, a e r o t h e r m a l and l a t e r f o r p i n p o i n t i n g t h e cause and c u r e f o r f i e l d modeling i s much b e t t e r u n d e r s t o o d and i s b e i n g used problems, when l o c a l y i e l d i n g i s suspected t o be o c c u r - t h r o u g h o u t t h e aerospace i n d u s t r y . T h i s i s n o t t o r i n g . As a r e s u l t , 3-D i n e l a s t i c s t r u c t u r a l a n a l y s i s say, however, t h a t a l l problems have been s o l v e d . The has been r e p o r t e d by p a r t i c i p a n t s t o be a s i g n i f i c a n t a c c u r a t e p r e d i c t i o n o f combustor a e r o t h e r m a l perform- advancement t h a t r e s u l t e d from HOST.

ance a l o n g w i t h p r e d i c t i o n o f w a l l t e m p e r a t u r e l e v e l s and g r a d i e n t s w i l l r e q u i r e f u r t h e r improvement i n Thermomechanical f a t i g u e t e s t i n g . I n t h e p a s t , numerical schemes w i t h i n p u t from e x p e r i m e n t a l , f u l l y - mechanical p r o p e r t i e s o f m e t a l l i c m a t e r i a l s have been s p e c i f i e d r e a c t i n g flow d a t a t h a t i s n o t y e t a v a i l a - d e t e r m i n e d e x p e r i m e n t a l l y u s i n g s i m p l e r mechanical and b l e . HOST was t e r m i n a t e d b e f o r e r e a c t i n g gas flow and t h e r m a l l o a d v a r i a t i o n s t h a n t h e complex v a r i a t i o n s f u e l s w i r l c h a r a c t e r i z a t i o n d a t a c o u l d be o b t a i n e d .

e x p e r i e n c e d i n many e n g i n e a p p l i c a t i o n s . The need t o However, a n a l y t i c a l procedures have improved t o t h e improve e n g i n e d u r a b i l i t y r e q u i r e s e v a l u a t i o n o f mate- p o i n t t h a t one o r g a n i z a t i o n i n d i c a t e d t h e use o f t h r e e - r i a l b e h a v i o r and l i f e under more r e a l i s t i c c o n d i t i o n s .

dimensional f l u i d flow a n a l y s i s i n t h e d e s i g n o f com- I n t h e HOST program, c o n t r a c t s , g r a n t s , and NASA b u s t o r s t h a t r e q u l r e d a minimum o f t e s t i n g .

in-house r e s e a r c h were conducted on e v a l u a t i n g m a t e r i a l There was an a l m o s t unanimous o p i n i o n o f those b e h a v i o r , i n c l u d i n g b o t h c r a c k p r o p o g a t i o n and m a t e r i a l commenting on combustor m o d e l i n g t h a t t h e HOST program d e f o r m a t i o n , as a f u n c t i o n o f t i m e , under c y c l i c b i a x - was l o n g overdue, and i t spearheaded t h e move toward i a l mechanical l o a d s , and i n numerous atmospheric and an a n a l y t i c c a p a b i l i t y i n combustor u n d e r s t a n d i n g and c y c l i c t e m p e r a t u r e e n v i r o n m e n t s . C y c l i c mechanical d e s i g n a n a l y s i s .

l o a d i n g s have i n c l u d e d h i g h f r e q u e n c y loads superim- posed on lower frequency l o a d s .

T u r b i n e h e a t t r a n s f e r . The HOST-sponsored a c t i v i - o f t h i s r e s e a r c h was The key o b j e c t i v e t o g a i n a t i e s i n t u r b i n e h e a t t r a n s f e r encompassed n e a r l y a l l b e t t e r u n d e r s t a n d i n g o f how and why c r a c k s d e v e l o p i n a s p e c t s o f i n t e r n a l and e x t e r n a l h e a t t r a n s f e r i n t u r - o f m a t e r i a l s exposed t o c y c l i c tempera- d i f f e r e n t t y p e s b i n e a i r f o i l s . Some o f t h e r e s e a r c h c o n t r a c t s and t u r e and mechanical l o a d i n g c o n d i t i o n s . These d a t a g r a n t s i n t h e o v e r a l l program i n c l u d e d e x t e r n a l a i r - o f e n g i n e e r i n g l i f e p r e d i c t i o n s meth- can be t h e b a s i s f o i l h e a t t r a n s f e r w i t h and w i t h o u t f i l m c o o l i n g , ods t h a t can be a p p l i e d t o t h e severe c o n d i t i o n s i n impingement c o o l i n g , i n t e r a c t i o n o f r o t o r and s t a t o r t h e e n g i n e h o t s e c t i o n . The d e f o r m a t i o n t e s t i n g p o r - i n a l a r g e low speed t u r b i n e , c o r i o l i s and buoyancy t i o n o f t h e r e s e a r c h s u p p o r t s t h e development o f v i s c o - e f f e c t s on h e a t t r a n s f e r i n c o o l a n t passages, h e a t p l a s t i c c o n s t i t u t i v e models f o r s t r u c t u r a l a n a l y s i s . t r a n s f e r w i t h flow a c r o s s a moving a i r f o i l t i p , and These mechanical p r o p e r t y d a t a a r e o b t a i n e d under end w a l l boundary l a y e r s t u d i e s . A s a r e s u l t o f t h i s more r e a l i s t i c c o n d i t i o n s and w i t h g r e a t e r p r e c i s i o n r e s e a r c h c o r r e l a t i o n s have been developed t h a t have t h a n were h e r e t o f o r e p o s s i b l e . A c c o r d i n g t o some o f r e s u l t e d i n s i g n i f i c a n t improvement i n accuracy o f c a l - t h o s e i n t e r v i e w e d , t h e d a t a base o f thermomechanical c u l a t e d b l a d e metal t e m p e r a t u r e s . A l s o q u a l i t y e x p e r i - m a t e r i a l p r o p e r t i e s p l u s e x p e r i m e n t a l d a t a from o t h e r mental d a t a s e t s , a l o n g w i t h good documentation, were phases o f HOST program may be one of t h e m o s t u s e f u l developed t h a t w i l l f i n d widespread use by h e a t a s p e c t s o f t h e HOST P r o j e c t . t r a n s f e r a n a l y s t s i n t h e f u t u r e . It i s now p o s s i b l e as a r e s u l t o f HOST t o b e t t e r c o n t r o l l o c a l tempera- Impact on Engine Development Process t u r e s , which i n t u r n , r e s u l t i n b e t t e r c o n t r o l o f b l a d e l i f e and s u r f a c e o x i d a t i o n . Improved engine d e s i g n c a p a b i l i t y . Both computer codes and e x p e r i m e n t a l d a t a bases developed under t h e P r o t e c t i v e c o a t i n g s . P r o t e c t i v e c o a t i n g s i n c l u d e HOST P r o j e c t have a l r e a d y been of v a l u e i n e n g i n e design. The impact i s expected t o be f e l t for y e a r s b o t h thermal b a r r i e r c o a t i n g s , t o reduce h e a t t r a n s - f e r , and o x i d a t i o n r e s i s t a n t c o a t i n g s . Progress has t o come. While t h e r e a r e c e r t a i n r e s e r v a t i o n s r e l a t - been made on i m p r o v i n g c o a t i n g s and a b e t t e r under- i n g t o t h e e x t e n t o f code development, t h e o v e r a l l s t a n d i n g o f i n t e r a c t i o n s between c o a t i n g s and s t r u c - t e c h n o l o g y generated by HOST w i l l c o n t i n u e to be use- f u l t h r o u g h o u t t h e a i r c r a f t e n g i n e i n d u s t r y . I t i s t u r a l base m a t e r i a l s . I n a d d i t i o n , thermomechanical f a t i g u e t e s t i n g has been conducted on m a t e r i a l s h a v i n g c l e a r t h a t t h e v a l u e of r e s e a r c h t h a t has developed b o t h computer codes and e x p e r i m e n t a l d a t a bases has o x i d a t i o n and thermal b a r r i e r c o a t i n g s . L i f e p r e d i c - t i o n models a r e b e i n g developed. A s i d e b e n e f i t o f been g r e a t e s t t o those c o n d u c t i n g t h e r e s e a r c h , b u t o t h e r o r g a n i z a t i o n s a r e c e r t a i n l y making use o f t h e t h i s r e s e a r c h was development o f an awareness t h a t d e s i g n e r s and m a t e r i a l s r e s e a r c h p e r s o n n e l must work r e s e a r c h r e s u l t s t o v a r y i n g degrees.

Design a n a l y s i s c a p a b i l i t i e s have been improved more c l o s e l y t o g e t h e r i n i m p r o v i n g l i f e p r e d i c t i o n model s . i n t h e combustor and t u r b i n e . As a r e s u l t o f t h e s e c a p a b i l i t i e s l e s s e x p e r i m e n t a t i o n i s r e q u i r e d i n d e v e l - Computer codes from t h e HOST P r o j e c t . The o u t p u t opment o f t h e components. I t i s expected t h a t r e l i a - b i l i t y w i l l be improved because of improvements i n t h e from HOST was t e c h n i c a l i n f o r m a t i o n i n t h e form o f r e s e a r c h r e p o r t s , e x p e r i m e n t a l d a t a s e t s , and computer p r e d i c t i o n o f temperatures and s t r e s s e s from h e a t t r a n s f e r , f l u i d flow, and i n e l a s t i c s t r e s s a n a l y s e s .

codes. A r e q u i r e m e n t i n t h e development o f computer codes was i n s t a l l a t i o n and o p e r a t i o n o f t h e codes on A t t h i s t i m e t h e r e has n o t been enough h i s t o r y gener- one or more o f t h e f o l l o w i n g NASA Lewis Research a t e d t o d e t e r m i n e if HOST has r e s u l t e d i n reduced main- Center computers: Cray X-MP/2-4 w i t h COS o p e r a t i n g tenance c o s t s , one of t h e g o a l s of t h e p r o j e c t . B u t i t i s r e a s o n a b l e t o expect t h a t i f d u r a b i l i t y and r e l i - system, Amdahl 5840 w i t h VM o p e r a t i n g system, or a b i l i t y a r e improved, maintenance c o s t s w i l l be VAX 11-750. T h i s r e q u i r e m e n t was aimed a t making t h e codes m r e g e n e r a l l y a v a i l a b l e and u s a b l e . I n some reduced.

Comments r e c e i v e d f r o m a number o f t h o s e i n t e r - cases t h e o r i g i n a l code development was on a more advanced computer model t h a n t h e one a t NASA Lewis. viewed i n d i c a t e d t h a t d a t a bases generated f r o m e x p e r i - M o d i f i c a t i o n t o make t h e code r u n a t NASA Lewis would ments i n f l u i d flow i n t h e combustor and t u r b i n e , have t h e advantage o f making i t workable on a w i d e r t u r b i n e h e a t t r a n s f e r , and thermomechanical f a t i g u e range o f computers. w i l l be a t l e a s t as i m p o r t a n t t o a n a l y s t s as t h e com- I n p r a c t i c e t h e above d e s c r i b e d concept has n o t p u t e r codes generated from HOST c o n t r a c t s . A s men- worked as w e l l as hoped. I n some cases codes deve- t i o n e d e a r l i e r i n t h i s paper, i t w i l l p r o b a b l y be some l o p e d by one o r g a n i z a t i o n have been r e a d i l y used by t i m e b e f o r e d e s i g n e r s a r e c o m f o r t a b l e w i t h , and w i l l o t h e r o r g a n i z a t i o n s . These have g e n e r a l l y been t h e r o u t i n e l y use, some o f t h e advanced computer codes s i m p l e r codes. I n o t h e r cases, however, t h e codes t h a t have been developed i n HOST.

from HOST have been o f o n l y l i m i t e d b e n e f i t t o t h e nondeveloper o f t h e code. For t h e more c o m p l i c a t e d Reduced engine development c o s t s . R e d u c t i o n i n codes, i t has been t h e e x p e r i e n c e o f NASA personnel engine development costs was n o t one o f t h e o r i g i n a l t h a t i t t a k e s from 3 t o 12 months t o debug and become g o a l s o f t h e HOST P r o j e c t , b u t i t has become a p o s s i - b l e s i g n i f i c a n t s i d e b e n e f i t . The computer codes and f a m i l i a r w i t h codes s u p p l i e d by HOST c o n t r a c t o r s for t h e NASA computers. A s i m i l a r p e r i o d o f t i m e i s d a t a bases developed i n HOST have improved d e s i g n capa- b i l i t i e s t o t h e e x t e n t t h a t l e s s development t e s t i n g expected to be needed by o t h e r u s e r s o f t h e code even though c o n s i d e r a b l e debugging was accomplished a t i s expected for new engines. However, reduced e x p e r i - mental t e s t c o s t s a r e c o u n t e r b a l a n c e d by i n c r e a s e d NASA. A s h o r t c o m i n g w i t h t h e s e codes i s t h a t s u p p o r t s e r v i c e cannot be p r o v i d e d b y t h e d e v e l o p e r o r NASA I n computer c o s t s i n t h e d e s i g n a n a l y s i s p r o c e s s . A com- t h e manner a v a i l a b l e f o r commercial codes. p l e t e l y c l e a r p i c t u r e has n o t emerged i n a l l cases.

A comment made by one o f those i n t e r v i e w e d m i g h t P a r t o f t h i s l a c k o f c l a r i t y r e s u l t s from s e v e r a l f a c - t o r s : ( 1 ) HOST has p l a y e d a s i g n i f i c a n t p a r t i n s o l v e t h i s p r o b l e m of computer code s u p p o r t . I n f u t u r e programs f u n d i n g s h o u l d be a l l o c a t e d f o r a commercial i m p r o v i n g t e c h n o l o g y i n engine h o t s e c t i o n s , b u t i t i s n o t a s o l e p l a y e r . O t h e r in-house, Independent s o f t w a r e company t o a d e q u a t e l y debug and document t h e Research and Development (IR&D), and government spon- more c o m p l i c a t e d computer codes. F u r t h e r , by p e r m i t - sored programs a r e a l s o r e s u l t i n g i n improved t e c h n o l - t i n g t h e s o f t w a r e company t o market t h e code t h e y would be i n a p o s i t i o n t o p r o v i d e a c o n t i n u i n g s u p p o r t and ogy. I t i s g e n e r a l l y d i f f i c u l t t o q u a n t i t a t i v e l y u p d a t i n g f u n c t i o n . I n t h i s manner codes developed d e f i n e t h e c o n t r i b u t i o n s of HOST t o o v e r a l l improve- ments i n t e c h n o l o g y ; (2) Each new e n g i n e development c o u l d be made a v a i l a b l e and u s a b l e by i n t e r e s t e d par- t i e s o v e r an extended p e r i o d o f t i m e . program u t i l i z e s advances i n t e c h n o l o g y compared t o t h e l a s t e n g i n e developed, o f t e n w i t h i n c r e a s e d com- Most o f those i n t e r v i e w e d s t a t e d t h a t w i t h o u t p l e x i t y a n d / o r designs t o h i g h e r l i m i t s o f tempera- code s u p p o r t t h e y c o u l d make o n l y l i m i t e d use o f codes t u r e , p r e s s u r e , s t r e s s , e t c . T h i s "moving t a r g e t " from HOST t h a t t h e y themselves d i d n o t develop. Some makes comparisons o f development c o s t s w i t h p r e v i o u s o r g a n i z a t i o n s d i d s t a t e , however, t h a t t h e y expected t o r e w r i t e p o r t i o n s o f some o f t h e codes o f i n t e r e s t . engines d i f f i c u l t ; ( 3 ) Computer c a p a b i l i t i e s a r e con- Another i n t e r v i e w e r s t a t e d t h a t a l t h o u g h a code may s t a n t l y i m p r o v i n g and c o s t s t o accomplish computing t a s k s a r e d e c r e a s i n g .

n o t be d i r e c t l y u s a b l e as developed by a n o t h e r o r g a n i - i t can be r e w r i t t e n i n about o n e - h a l f t h e t i m e C o n s i d e r a t i o n of a l l these f a c t o r s makes i t d i f f i - z a t i o n , o r i g i n a l l y r e q u i r e d t o w r i t e t h e code. I t a l s o i s pos- c u l t t o draw d e f i n i t i v e c o n c l u s i o n s as t o whether, o r how much, HOST has a c t u a l l y reduced e n g i n e development s i b l e t o c a p i t a l i z e on problems t h a t may have been experienced by t h e o r i g i n a l programmer so t h a t t h e c o s t s . However, t h e f o l l o w i n g a r e i n f o r m e d o p i n i o n s t h a t were p r e s e n t e d by some of those i n t e r v i e w e d : r e w r i t t e n code w i l l be s u p e r i o r to t h e o r i g i n a l .

1 . Compdting methods t h a t have been developed 1 . "There h a s n ' t been a n o t h e r forum i n t h e U.S.

under HOST have r e s u l t e d i n annual s a v i n g s o f s e v e r a l t o compare t o t h e HOST Annual Workshops t h a t has m i l l i o n s o f d o l l a r s i n reduced computer t i m e for t h e b r o u g h t t o g e t h e r t h e r i g h t m i x o f people t o d i s c u s s r e q u i r e d number o f computer r u n s i n engine development r e s e a r c h o f common i n t e r e s t . " programs.

2 . "Workshops p r o v i d e an annual update i n t h e 2. A HOST-developed computer code t h a t t r a n s f o r m s t h i n k i n g and p l a n n i n g by b o t h NASA and i n d u s t r y . T h i s temperatures from t h e o u t p u t of c o u r s e - g r i d f i n i t e e l e - once-a-year c o n t a c t between i n d u s t r y and academia i s ment h e a t t r a n s f e r analyses to t h e i n p u t o f f i n e - g r i d o f g r e a t v a l u e . " f i n i t e element s t r u c t u r a l a n a l y s e s has reduced e n g i - n e e r i n g l a b o r by 26 man-years p e r y e a r f o r one company. 3 . "The casual c o n v e r s a t i o n s w i t h o t h e r p a r t i c i - p a n t s t h a t t a k e p l a c e a t t h e c o f f e e breaks a r e of such 3. I n c r e a s e d computer c o s t s u s i n g t h r e e - s i g n i f i c a n t b e n e f i t t h a t NASA should c o n s i d e r i n c r e a s - d i m e n s i o n a l f l u i d flow and i n e l a s t i c s t r e s s analyses i n g t h e number o f c o f f e e breaks and p r o v i d i n g more t h a t r e s u l t i n more r e f i n e d d e s i g n s a r e j u s t about b a l - i n f o r m a l g e t - t o g e t h e r s . " anced b y reduced e x p e r i m e n t a l t e s t i n g c o s t s for these d e s i g n s a t t h e p r e s e n t t i m e . B u t t h e a n a l y t i c a l c o s t s 4 . "HOST workshops have p r o v i d e d an e x c e l l e n t a r e .dropping r a p i d l y , so c o s t s a v i n g s a r e expected f o r u m f o r p r o b i n g d i s c u s s i o n s and t h e " g i v e and t a k e " soon. necessary t o g e n e r a t e u s e f u l knowledge and understand- i n g f o r a l l p a r t i c i p a n t s o f t h e advantages and d l s a d - 4 . I t i s e s t i m a t e d t h a t i f development o f new vantages o f v a r i o u s approaches. These d i s c u s s i o n s engines had t o use 1975 v i n t a g e d e s i g n and t e s t i n g have a i d e d companies t o e v a l u a t e t h e d i r e c t i o n s of t e c h n o l o g y , t h e c o s t o f e n g i n e development would be t h e i r own r e s e a r c h . " a p p r o x i m a t e l y t h r e e t i m e s as h i g h as p r e s e n t l y exper- i e n c e d when u s i n g advanced t e c h n o l o g y i n which HOST 5 . "The workshops a r e u s e f u l i n p r o v i d i n g and has been a s i g n i f i c a n t c o n t r i b u t o r . The o v e r a l l sav- d e v e l o p i n g r e l a t i o n s h i p s w i t h peers from o t h e r o r g a n i - i n g s a r e measured i n b i l l i o n s o f d o l l a r s . z a t i ons , 1 n c l u d i ng NASA. " 5 . I t i s reasonable t o e x p e c t t h a t improved p r e - 6. "The HOST workshops a r e e x t r e m e l y e f f e c t i v e d i c t i v e c a p a b i l i t y i n e n g i n e d e s i g n can reduce t e s t i n g because t h e t e c h n i c a l community i s b e t t e r r e p r e s e n t e d r e q u i r e m e n t s . I f t h i s improvement can e l i m i n a t e j u s t t h a n a t s o c i e t y m e e t i n g s . " one d e s i g n or t e s t - b u i l d i t e r a t i o n d u r i n g a development o r d e m o n s t r a t o r program, s a v i n g s o f $250,000 or more From t h e above sampling o f comments i t i s e v i d e n t can be r e a s o n a b l y claimed. Moreover, t h e c o s t s a v i n g s t h a t one o f t h e b i g s t r e n g t h s o f t h e HOST P r o j e c t was by e l i m i n a t i n g one s e r v i c e - r e v e a l e d d e f i c i e n c y c o u l d n o t o n l y t h e r e s e a r c h and t e c h n o l o g y generated, b u t be an o r d e r o f magnitude g r e a t e r . t h e t i m e l y d i s s e m i n a t i o n o f t h i s i n f o r m a t i o n t h r o u g h f o r m a l p r e s e n t a t i o n s and i n f o r m a l d i s c u s s i o n s i n t h e From t h e above comments i t i s o b v i o u s t h a t i n some workshops.

cases h a r d numbers can be generated f o r c o s t s a v i n g s r e s u l t i n g from HOST. I n o t h e r cases s a v i n g s can be Impact on I n d u s t r y - U n i v e r s i t y - G o v e r n m e n t P a r t n e r s h i p i n f e r r e d b u t n o t n e c e s s a r i l y f i r m l y documented. How- e v e r , e n g i n e m a n u f a c t u r i n g company p e r s o n n e l comments Improved r e l a t i o n s h i p s . There was a consensus which r e l a t e t o engine development c o s t r e d u c t i o n s and t h a t t h e HOST P r o j e c t , l a r g e l y t h r o u g h t h e workshops, s a v i n g s r e s u l t i n g from r e d u c i n g s e r v i c e - r e v e a l e d d e f i - s u b s t a n t i a l l y improved r e l a t i o n s h i p s o f p e r s o n n e l i n c i e n c i e s p r o v i d e r e a s o n a b l e c e r t a i n t y t h a t p r o j e c t e d i n d u s t r y , academia, and government. The program a l s o s a v i n g s a r i s i n g from HOST-generated t e c h n o l o g y w i l l be p r o v i d e d o p p o r t u n i t i e s for u n i v e r s i t y p r o f e s s o r s t o o r d e r s of magnitude g r e a t e r t h a n t h e cost o f t h e work d i r e c t l y with e n g i n e m a n u f a c t u r e r s . T h i s a r r a n g e - p r o j e c t i t s e l f . ment was a d o u b l e b a r r e l l e d b e n e f i t ; t h e companies were a b l e t o c a p i t a l i z e on p r e s e n t and p r e v i o u s u n i v e r s i t y Impact on Technology T r a n s f e r r e s e a r c h , and t h e p r o f e s s o r s developed a b e t t e r under- A p p r o x i m a t e l y 250 t e c h n i c a l r e s e a r c h r e p o r t s have s t a n d i n g o f t h e environment and problems o f e n g i n e been w r i t t e n i n t h e HOST P r o j e c t and numerous computer m a n u f a c t u r e r s which t h e y c o u l d pass on t o t h e i r codes have been generated. I n a d d i t i o n s i x annual s t u d e n t s .

major workshops were h e l d as w e l l as a number o f One u n i v e r s i t y p r o f e s s o r s t a t e d t h a t he, a l o n g mini-workshops devoted t o a s i n g l e a r e a o f r e s e a r c h . w i t h o t h e r s , had h e l d d l s c u s s i o n s f o r a number o f Because o f t h e l a r g e attendance o f 250 t o 300 a t each y e a r s on how t o g e t b e t t e r i n t e r a c t i o n between indus- annual workshop, which had b o t h f o r m a l p r e s e n t a t i o n s t r y and u n i v e r s i t i e s . He t h e n s a i d , "HOST d i d i t ! " and i n f o r m a l d i s c u s s i o n s , t h e r e was a maximum o p p o r t u - As a r e s u l t , he f e e l s t h a t companies and u n i v e r s i t i e s n i t y for i n f o r m a t i o n exchange and t e c h n o l o g y t r a n s - a r e now w o r k i n g t o g e t h e r b e t t e r .

f e r . Since r e p r e s e n t a t i v e s from a l l l a r g e U.S. e n g i n e A l t h o u g h m o s t o f those i n t e r v i e w e d emphaslzed t h e manufacturers, as w e l l as many from academia, r e s e a r c h improved r e l a t i o n s between i n d u s t r y and u n i v e r s i t i e s , i n s t i t u t e s , and government, a t t e n d e d t h e s e workshops, s e v e r a l a l s o commented t h a t t h e HOST program improved t h e r e was p r o b a b l y a b e t t e r t r a n s f e r of t e c h n o l o g y t h e i r r e l a t i o n s h i p w i t h NASA. I n a d d i t i o n s e v e r a l were t h a n from any o t h e r NASA-sponsored a i r c r a f t engine v e r y complementary about t h e NASA o r g a n i z a t i o n and man- agement o f t h e HOST program. They f e l t t h a t t h e pro- r e s e a r c h or development p r o j e c t .

There was a unanimous o p i n i o n o f those i n t e r v i e w e d gram was w e l l conceived, and t h e NASA managers were b o t h knowledgeable and h e l p f u l i n overcoming problems t h a t t h e two-day workshops were h i g h l y s u c c e s s f u l . Not o n l y were t h e p r e s e n t a t i o n s u s e f u l , b u t t h e i n f o r m a l t h a t developed d u r i n g t h e course o f i n v e s t i g a t i o n s .

d i s c u s s i o n s t h a t o c c u r r e d d u r i n g breaks i n t h e presen- t a t i o n s and d u r i n g t h e evening a f t e r t h e p r e s e n t a t i o n s Enthusiasm o f p a r t i c i p a n t s . E s s e n t i a l l y everyone w e r e deemed e x t r e m e l y b e n e f i c i a l . Some comments made i n t e r v i e w e d showed enthusiasm f o r t h e HOST P r o j e c t , by t h o s e i n t e r v i e w e d i n c l u d e : b u t t h e degree o f enthusiasm d i f f e r e d b o t h by o r g a n i z a t i o n and i n d i v i d u a l . Among t h e l a r g e r o r g a n i - t o encourage t h i r d - p a r t y m a n u f a c t u r i n g o f such develop- z a t i o n s t h e r e appeared t o be a g e n e r a l c o r r e l a t i o n i n g t e c h n o l o g y .

between enthusiasm and t h e degree o f p a r t i c i p a t i o n The f o l l o w i n g comments expressed by o n l y one o r (number o f c o n t r a c t s ) i n HOST. There i s some i n d i c a - two i n d i v i d u a l s may n o t be a consensus o f t h o s e i n t e r - t i o n t h a t t h e o r g a n i z a t i o n a l enthusiasm a l s o may be viewed, b u t many have m e r i t and r e q u i r e c o n s i d e r a t i o n s i g n i f i c a n t l y i n f l u e n c e d by t h e degree o f enthusiasm for f u t u r e c o n t r a c t e f f o r t s : o f t h e HOST c o o r d i n a t o r for t h a t o r g a n i z a t i o n . I t has been i n d i c a t e d b y NASA p e r s o n n e l t h a t t h e same o r g a n i - 1 . Rather t h a n f u n d so many r e s e a r c h areas as i n z a t i o n a l enthusiasm was e v i d e n t p r i o r t o award o f con- HOST, fewer areas s h o u l d be more g e n e r o u s l y funded.

t r a c t s . I t seems t h a t enthusiasm by a l e a d e r i s c o n t a g i o u s .

2 . HOST was w o r t h w h i l e , b u t from t h e company I t appeared t h a t t h o s e i n t e r v i e w e d from u n i v e r s i - s t a n d p o i n t t h e b e n e f i t would have been g r e a t e r w i t h a t i e s , on t h e average, showed a g r e a t e r degree o f enthu- h a r d w a r e - o r i e n t e d program t h a t would have r e s u l t e d i n siasm t h a n t h o s e from i n d u s t r y , p o s s i b l y because an advanced engine t h a t c o u l d be marketed. (It s h o u l d u n i v e r s i t y p e r s o n n e l l e s s o f t e n have t h e o p p o r t u n i t y be p o i n t e d o u t t h a t t h i s was a m i n o r i t y comment. Many t o be i n v o l v e d w i t h a p r o j e c t o f t h e magnitude o f HOST.

more o f t h o s e i n t e r v i e w e d s t r e s s e d t h e v a l u e o f a O t h e r reasons f o r t h e i r e n t h u s i a m were expressed i n r e s e a r c h - o r i e n t e d program.)

t h e i r i n t e r v i e w s . For some i t was t h e first o p p o r t u - n i t y f o r t h e r e s u l t s o f t h e i r r e s e a r c h t o be used 3. More f u n d s should have been made a v a i l a b l e i n d i r e c t l y by an i n d u s t r i a l concern. To f i n d t h a t what HOST f o r t e c h n o l o g y t r a n s f e r f r o m t h e o r g a n i z a t i o n you a r e d o i n g i s u s e f u l t o a l a r g e o r g a n i z a t i o n c e r - d o l n g t h e r e s e a r c h t o o t h e r o r g a n i z a t i o n s . As s t a t e d t a i n l y can be e x h i l a r a t i n g . HOST a l s o p e r m i t t e d some e a r l i e r i n t h i s paper. f u n d i n g o f an o r g a n i z a t i o n t o r e s e a r c h e r s f r o m u n i v e r s i t i e s to d e p a r t somewhat from p r o v i d e s u p p o r t and u p d a t i n g o f computer programs t h e i r m r e academic a c t i v i t i e s and work on r e a l prob- would be e x t r e m e l y b e n e f i c i a l .

lems r e l e v a n t t o i n d u s t r i a l concerns. T h i s t y p e o f work and i n t e r a c t i o n w i t h e n g i n e m a n u f a c t u r e r s has t h e 4 . Small o r g a n i z a t i o n s c o u l d n o t p a r t i c i p a t e t o o f b r i n g i n g " t h e r e a l w o r l d " i n t o t h e added b e n e f i t any g r e a t e x t e n t i n HOST u n l e s s t h e y teamed w i t h a c l a s s r o o m t o g u i d e s t u d e n t s i n t h e d i r e c t i o n s o f prob- l a r g e r o r g a n i z a t i o n .

lems p r e s e n t l y f a c i n g a t l e a s t one segment o f t h e i n d u s t r i a l w o r l d . Another b e n e f i t i n c l u d e d g u i d i n g 5. Some c o n t r a c t s were awarded based upon e s t i - some g r a d u a t e s t u d e n t s towards employment i n t h e a i r - mated c o s t s r a t h e r t h a n on t h e o r g a n i z a t i o n ' s c a p a b i l i - c r a f t e n g i n e i n d u s t r y because o f t h i s exposure. t i e s and e x p e c t a t i o n s o f p r o d u c i n g a l l t h a t was A f a c t o r i n f l u e n c i n g t h e enthusiasm o f u n i v e r s i t y promi sed i n t h e p r o p o s a l .

p r o f e s s o r s has been t h e workshops. A t t h e s e annual m e e t i n g s t h e r e has been o p p o r t u n i t y for i n t e r a c t i o n 6. B u i l d i n g NASA in-house f a c i l i t i e s was overdone, w i t h a p p r o p r i a t e q u a l i t y and q u a n t i t y o f i n d u s t r i a l p a r t i c u l a r l y f o r thermomechanical f a t i g u e t e s t i n g .

p e r s o n n e l . For some t h i s has been a new e x p e r i e n c e .

P r e v i o u s r e l a t i o n s w i t h i n d u s t r i a l p e r s o n n e l had been A l t h o u g h n o t a l l o f t h e above comments may be o f on a more l i m i t e d b a s i s t o a few p e o p l e t h e y have met a p o s i t i v e n a t u r e , t h e r e may be m e r i t t o many, and a l l a t s o c i e t y m e e t i n g s , or t o a few e n g i n e e r s i n an indus- s h o u l d be g i v e n c o n s i d e r a t i o n .

t r y where t h e y have had a c o n t r a c t . G e n e r a l l y , t h e y never have had t h e o p p o r t u n i t y t o i n t e r a c t w i t h so SUMMARY OF FINDINGS many q u a l i t y p e o p l e from i n d u s t r y h a v i n g i n t e r e s t s s i m - i l a r t o t h e i r s .

From i n t e r v i e w s conducted w i t h 41 i n d u s t r y , u n i - v e r s i t y , and government p e r s o n n e l s o l i c i t i n g t h e i r C o n s i d e r a t i o n s f o r F u t u r e C o n t r a c t Efforts views on t h e impact o f HOST t h e m a j o r f i n d i n g s can be A l t h o u a h most comments r e c e i v e d i n t h e i n t e r v i e w s summarized as f o l l o w s : were f a v o r a 6 l e on how t h e HOST P r o j e c t was conducted and on t h e r e s u l t s o b t a i n e d , some comments r e c e i v e d 1 . There was 100 p e r c e n t agreement t h a t t h e HOST c o u l d p o s s i b l y p r o v i d e some improvements r e l a t i v e t o P r o j e c t was h i g h l y s u c c e s s f u l and w o r t h w h i l e .

HOST i n f u t u r e c o n t r a c t e f f o r t s .

An o f t e n expressed comment from t h o s e i n t e r v i e w e d 2. The HOST approach f o r expending r e s e a r c h f u n d s concerned t h e e a r l i e r - t h a n - e x p e c t e d t e r m i n a t i o n o f t h e was v e r y e f f e c t i v e . The emphasis on r e s e a r c h r a t h e r HOST P r o j e c t because o f NASA b u d g e t a r y c o n s i d e r a t i o n s .

t h a n hardware development was viewed by s e v e r a l i n t e r - Because o f t h i s e a r l y t e r m i n a t i o n some programs were viewed as t h e r o l e NASA r e s e a r c h c e n t e r s s h o u l d t a k e t o p r o v i d e l o n g l a s t i n g b e n e f i t s t o t h e a i r c r a f t indus- n o t a b l e t o be completed. The main concerns expressed were ( 1 ) e x p e r i m e n t a l v e r i f i c a t i o n o f computer codes t r y . Having many o r g a n i z a t i o n s w o r k i n g t o a common i s i n c o m p l e t e , and ( 2 ) r e a c t i o n k i n e t i c s was n o t i n v e s - goal and many o f t h e o r g a n i z a t i o n s h a v i n g s i m i l a r pro- t i g a t e d i n t h e combustor a e r o t h e r m a l m o d e l i n g programs grams l e d t o " c r o s s f e r t i l i z a t i o n " t h a t improved t h e as o r i g i n a l l y planned. A t t h i s t i m e i t i s u n c e r t a i n r e s e a r c h for each o r g a n i z a t i o n .

when t h i s added r e s e a r c h can be completed. I t may t a k e y e a r s b e f o r e f u n d s a r e a v a i l a b l e t o conduct t h e 3. HOST y i e l d e d advantages o v e r t r a d i t i o n a l r e s e a r c h . I t would c e r t a i n l y be b e n e f i c i a l i n f u t u r e r e s e a r c h and t e c h n o l o g y c o n t r a c t e d e f f o r t s by p r o v i d - programming e f f o r t s t o t r y t o a v o i d e a r l y t e r m i n a t i o n i n g a f o c u s and a c c e l e r a t i o n t o problems i n v o l v i n g t h e o f s u c c e s s f u l p r o j e c t s . e n t i r e h o t s e c t i o n o f engines. I n a d d i t i o n HOST A s mentioned e a r l i e r , concern was expressed by r e s u l t e d i n a w o r k i n g r e l a t i o n s h i p between i n d u s t r y , some o f t h e n o n p a r t i c i p a n t s i n i n s t r u m e n t a t i o n academia, and government n o t p r e v i o u s l y e x p e r i e n c e d .

r e s e a r c h . T h i s r e s e a r c h was deemed t o be o f l i t t l e v a l u e t o those e x c e p t f o r t h e d e v e l o p e r because t h e 4. The annual workshops were a m a j o r c o n t r i b u t o r i n s t r u m e n t s developed were n o t a v a i l a b l e for purchase. t o t h e success o f HOST. C r i t i q u e s o f t h e r e s u l t s p r e - C o n s i d e r a t i o n should be g i v e n i n program p l a n n i n g to sented were an a i d i n d e v e l o p i n g improved programs.

e v a l u a t e t h e p r o b a b l e b e n e f i t s t o a l l p a r t i c i p a n t s or The i n f o r m a t i o n was d i s t r i b u t e d t o a l l concerned i n a d i f f i c u l t t e c h n i c a l c h a l l e n g e s o f t h e p r o j e c t , h i g h - more t i m e l y manner t h a n w a i t i n g u n t i l r e p o r t s were com- c a l i b e r p e o p l e were i n v o l v e d , i n c l u d i n g l e a d i n g p l e t e d and d i s t r i b u t e d . The l a r g e g a t h e r i n g s o f h i g h l y e x p e r t s i n each d i s c i p l i n e . T h i s q u a l i t y o f t h e q u a l i f i e d r e s e a r c h p e r s o n n e l f r o m a l l m a j o r o r g a n i z a - r e s e a r c h e r s was always apparent i n t h e t e c h n o l o g y o f improved e n g i n e r e l i a b i l - t i o n s h a v i n g a common goal developed.

i t y p r o v i d e d a t i m e l y i n t e r c h a n g e o f i n f o r m a t i o n . The approach to a d d r e s s i n g d u r a b i l i t y c h a l l e n g e s or more o f t h e f o l l o w i n g : h i g h e r - can i n c l u d e one 5 . The computer codes and d a t a bases t h a t were t e m p e r a t u r e m a t e r i a l s , more e f f e c t i v e c o o l i n g tech- generated w i l l be u s e f u l to a n a l y s t s f o r y e a r s t o come.

n i q u e s , advanced s t r u c t u r a l d e s i g n concepts, and However, some o f t h e l a r g e r codes may n o t be used by improved d e s i g n a n a l y s i s t o o l s . Because o f t h e poten- o r g a n i z a t i o n s which d i d n o t d e v e l o p t h e n because of t i a l g a i n s and perhaps because o f t h e t i m e l y g r o w t h i n l a c k o f code s u p p o r t . These computer codes c o u l d have computer hardware and a v a i l a b i l i t y , t h e HOST P r o j e c t ' s been made more u s e f u l by b r i n g i n g i n commercial soft- approach was on improved d e s i g n a n a l y s i s tools. To ware companies t o p r o v i d e code s u p p o r t , t o keep t h e b e t t e r understand t h e p h y s i c s i n v o l v e d i n t h e develop- codes updated, and t o market them f o r g e n e r a l use. ment o f t h e s e d e s i g n a n a l y s i s t o o l s f o r combustors and t u r b i n e s , h i g h - q u a l i t y experiments were o f t e n con- 6 . NASA was lauded f o r program concept and man- ducted. E a r l y p r o j e c t p l a n s i n c l u d e d s i g n i f i c a n t t e s t - agement. The program managers were deemed t o be tech- i n g i n t h e new High Pressure F a c i l i t y a t NASA Lewis n i c a l l y competent and h e l p f u l i n overcoming problems l i m - Research C e n t e r . However, t e c h n i c a l problems t h a t t h a t developed i n v a r i o u s c o n t r a c t s . i t e d f u l l t e s t i n g c a p a b i l i t y , l i m i t e d o p e r a t i n g f u n d s , and a move toward l e s s component t e s t i n g a t Lewis l e d 7 . While most o f t h e comments on t h e HOST P r o j e c t t o m o t h b a l l i n g o f t h e f a c i l i t y e a r l y i n 1986. T h i s were f a v o r a b l e , comments c r i t i c a l o f t h e p r o j e c t a l s o had a s i g n i f i c a n t impact on HOST, f i r s t , i n g r e a t l y may have m e r i t and s h o u l d be g i v e n c o n s i d e r a t i o n i n r e d u c i n g model/code v e r i f i c a t i o n t e s t i n g and, second, f u t u r e government sponsored p r o j e c t s . i n r e d u c i n g immediate use o f HOST-developed instrumen- t a t i o n f o r h o t s e c t i o n r e s e a r c h .

8. A s i d e b e n e f i t o f HOST has been t h e p o t e n t i a l Most r e s e a r c h r e s u l t s f r o m HOST were g e n e r i c .

f o r s i g n i f i c a n t l y r e d u c i n g t h e c o s t o f e n g i n e develop- They were a p p l i e d t o b o t h l a r g e and s m a l l t u r b i n e ment u s i n g advanced d e s i g n t e c h n i q u e s developed by e n g i n e s . I n a d d i t i o n c e r t a i n codes were used o u t s i d e HOST-sponsored r e s e a r c h . o f t h e HOST P r o j e c t for d u r a b i l i t y improvements i n t h e Space S h u t t l e Main Engine as w e l l as d e s i g n a n a l y s i s 9 . The c o s t r e d u c t i o n s i n engine development o f an advanced communications t e c h n o l o g y s a t e l l i t e .

p l u s s a v i n g s f r o m r e d u c i n g s e r v i c e - r e v e a l e d d e f i c i e n - There a r e , however, unique d u r a b i l i t y c h a l l e n g e s i n c i e s ( a r e s u l t o f b e t t e r p r e d i c t i v e c a p a b i l i t y i n small t u r b i n e engines which c o u l d n o t be addressed i n e n g i n e d e s i g n ) a r e p r o j e c t e d t o be o r d e r s o f magnitude HOST because o f f u n d i n g c o n s t r a i n t s . These c h a l l e n g e s g r e a t e r t h a n t h e c o s t o f t h e HOST P r o j e c t . i n c l u d e h i g h e r t u r b i n e b l a d e attachment s t r e s s e s , f a s t e r t h e r m a l t r a n s i e n t s , and d i f f e r e n t m a t e r i a l s .

10. A t t h e p r e s e n t t i m e t h e r e a r e n o t d e f i n i t i v e Such c h a l l e n g e s i n t o d a y ' s small engines a r e b e l i e v e d answers t o t h e q u e s t i o n o f whether t h e g o a l s o f t h e t o be t h e c h a l l e n g e s i n t o m o r r o w ' s l a r g e engines.

HOST P r o j e c t o f improved e n g i n e r e l i a b i l i t y and reduced Experience has shown t h a t , i n g e n e r a l , develop- maintenance c o s t s have been met because engines have ment o f new d e s i g n a n a l y s i s t o o l s i s f o l l o w e d by slow n o t y e t been produced t h a t u t i l i z e t h e improved tech- T h i s slow acceptance has appeared i n u s e r acceptance.

n o l o g y r e s u l t i n g from HOST. There i s reason t o some a s p e c t s o f t h e HOST P r o j e c t . Sometimes accept- b e l i e v e , however, t h a t t h e s u p e r i o r d e s i g n t e c h n i q u e s ance t i m e i s reduced d u r i n g a c r i s i s , such as coming f r o m HOST r e s e a r c h can r e s u l t i n b e t t e r e n g i n e i n - s e r v i c e engine problems.

r e l i a b i l i t y , improved f l i g h t s a f e t y , and u l t i m a t e l y While a r e t u r n on t h e i n v e s t m e n t i n HOST has reduced maintenance costs.

a l r e a d y been r e a l i z e d , a d d i t i o n a l r e t u r n l i e s i n t h e f u t u r e as a n a l y s t s use HOST codes more, and as such CONCLUDING REMARKS codes a r e used as t h e b a s i s f o r d e v e l o p i n g new codes f o r d e s i g n a n a l y s i s a p p l i c a b l e t o h i g h - t e m p e r a t u r e com- The HOST P r o j e c t a c t i v i t i e s encompassed r e s e a r - p o s i t e and s t r u c t u r a l ceramic m a t e r i a l s . Technology chers f r o m i n d u s t r y , academia, and government. Per- development for these m a t e r i a l s was o u t s i d e t h e scope haps due t o t h e s i z e and v i s i b i l i t y as w e l l as t h e o f t h e HOST P r o j e c t .

Report Documentation Page

National Aeronautics and 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No.

NASA TM-4087 4. Title and Subtitle 5. Report Date Toward Improved Durability in Advanced Aircraft Engine April 1989 Hot Sections 7. Author@) 8. Performing Organization Report No.

D. E. Sokolowski, Editor E-4468 10. Work Unit No.

505-63- 1B 9. Performing Organization Name and Address 11. Contract or Grant No.

National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio 44135-3191 13. Type of Report and Period Covered Technical Memorandum la. Sponsoring Agency Name and Address National Aeronautics and Space Administration 14. Sponsoring Agency Code Washington, D.C. 20546-0001 5. Supplementary Notes Also printed as a compilation of papers presented at the 33rd ASME International Gas Turbine and Aeroengine Congress and Exposition, Amsterdam, The Netherlands, June 5-9, 1988 (IGTI-Vol. 2).

6. Abstract Advanced aircraft turbine engine durability needs were addressed in the NASA sponsored Hot Section Technology (HOST) Project. The seven year project, which was concluded in late 1987, involved representatives from six engineering disciplines who were spread across three work sectors. To address more fully the technology needs resulting from durability challenges, the NASA Lewis Research Center encouraged researchers from the disciplines of instrumentation, combustion, turbine heat transfer, structural analysis, fatigue and fracture, and surface protection to work together, and prompted both basic and applications-oriented research within each of the six disciplines. This involved scientists and engineers from three work sectors: academia, where significant basic research usually is performed; industry, where research as well as applications work is addressed; and NASA, which supports both basic and applications research and has the resources to link the other two sectors.

Research results from the HOST project have been reported in approximately 250 technical reports. The ASME 33rd International Gas Turbine and Aeroengine Congress and Exposition, conducted in June 1988, provided a timely and most appropriate forum in which to summarize such research results. The one-day session entitled “Toward Improved Durability in Advanced Aircraft Engine Hot Sections” and this volume of the session’s papers is the result.

17. Key Words (Suggested by Author@)) 18. Distribution Statement

Turbine engine; Combustor; Turbine; Durability; Unclassified - Unlimited

Instrumentation; CDmbustion; Heat transfer; Subject Category 07 Structural analysis; Fatigue and fracture; Thermal barrier coating 9. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No of pages 22. Price’

Unclassified Unclassified 128 A07