Energy efficient engine program contributions to aircraft fuel conservation

NASA Technical Memorandum 83741 1'

Energy Efficient Engine Program

Contributions to Aircraft

Fuel Conservation

Peter G. Batterton Lewis Research Center Cleveland, Ohio Prepared for the Aviation Fuel Conservation Symposium I' sponsored by the Federal Aviation Administration Washington, D.C., September 10-1 1 , 1984 ENERGY EFFICIENT ENGINE PROGRAM CONTRIBUTIONS TO AIRCRAFT FUEL CONSERVATION by Peter G. Batterton National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio 44135 BACKGROUND Because o f t h e 1973 OPEC o i l embargo, t h e p r i c e o f j e t f u e l n e a r l y t r i p l e d and t h e Energy Crisis s t a r t e d . During t h e n e x t c o u p l e o f years, NASA performed s e v e r a l s t u d i e s t o e s t a b l i s h e n e r g y / t r a n s p o r t a t l o n research programs t o s u b s t a n t i a l l y r e d u c e f u e l consumption by t r a n s p o r t a i r c r a f t .

One s u c h program was t h e JT8D-Refan P r o g r a n . I n J a n u a r y 1975, (0 however, N A S A was s p e c i f i c a l l y r e q u e s t e d by t h e S e n a t e cv cv cv ~ I ~ Committee on A e r o n a u t i c a l and Space S c i e n c e s t o e s t t b l i s h a w r e s e a r c h program t h a t would have t h e r e d u c t - o n o f f u t u r e a i r c r a f t f u e l consumption as I t s prime o b j e c t i v e . N A S A assembled a t a s k f o r c e c o n s i s t i n g o f N A S A , Department o f T r a n s p o r t a t i o n , F e d e r a l A v i a t i o n A d m i n i s t r a t i o n , and t h e Department of Defense w i t h a s s i s t a n c e from e n g i n e and airframe m a n u f a c t u r e r s , a i r l i n e s and several a d v i s o r y b o a r d s . The t a s k f o r c e produced a r e p o r t o u t l i n i n g t h i s p l a n which was c a l l e d t h e Aircraft Energy E f f i c i e n c y ( A C E E ) progrsm (see R e f e r e n c e 1 f o r a n o v e r v i e w o f t h e e n t i r e ACEE Program).

The s i x b a s i c elements of t h e p l a n a r e shown i n F i g u r e 1. O f t h e s e s i x , t h r e e a r e airframe related and t h r e e are p r o p u l s i o n r e l a t e d . The t h r e e airframe e l e m e n t s were c o m p o s i t e s t r u c t u r e s f o r l i g h t e r weight, t h e Energy E f f i c i e n t T r a n s p o r t w i t h advanced aerodynamics a n d a c t i v e c o n t r o l s f o r b o t h w e i g h t and d r a g r e d u c t i o n , and l a m i n a r f l o w c o n t r o l f o r drag r e d u c t i o n . The t h r e e p r o p u l s i o n e l e m e n t s were Engine Component Improvement, a n e a r term program t o improve e f f i c i e n c y and i d e n t i f y s o u r c e s of d e t e r i o r a t i o n i n t h e n p r o d u c t i o n e n g i n e s ; t h e Energy E f f i c i e n t Engine, a l a t e 1 9 8 0 r s advanced t e c h n o l o g y t u r b o f a n and s u b j e c t of t h i s p r e s e n t a t i o n ; and t h e Advanced Turboprop, w i t h t h e greatest f u e l s a v i n g s p o t e n t i a l b u t a much h i g h e r r i s k e f f o r t . The t o t a l program g o a l was t o e s t a b l i s h t e c h n o l o g y f o r a 50% f u e l r e d u c t i o n f o r t r a n s p o r t a i r c r a f t b y 1985. The p l a n was approved by t h e S e n a t e i n November of 1975.

The Energy E f f i c i e n t Engine ( E E E ) used f u e l e f f i c i e n c y as a prime o b j e c t i v e b u t a l s o f a c t o r e d i n d i r e c t o p e r a t i n g c o s t and e n v i r o n m e n t a l a c c e p t a b i l i t y . The EEE would be a !'clean s h e e t of p a p e r r r d e s i g n w i t h 1985 b e i n g t h e target date f o r i n t r o d u c t i o n . The main o b j e c t i v e s of t h e EEE program were:

- A t l e a s t 1 2 p e r c e n t r e d u c t i o n i n s p e c i f i c f u e l

consumption w i t h a t l e a s t a 50 p e r c e n t r e d u c t i o n i n performance d e t e r i o r a t i o n rate

- Improve d i r e c t o p e r a t i n g c o s t s by a t l e a s t 5 p e r c e n t

- Meet f u t u r e e n v i r o n m e n t a l r e g u l a t i o n s s u c h as the

FAA 1978 FAR-36 n o i s e and EPA 1981 e r i s s i o n s s t a n d a r d s ENERGY EFFICIENT ENGINE PROGRAM OVE3VIEW F i g u r e 2 shows t h e program s c h e d u l e as it is u l t i m a t e l y b e i n g completed, b u t I t can be u s e d t o g e n e r a l l y o u t l i n e t h e program. The program is p r i m a r i l y a $200+M c o n t r a c t e d e f f o r t w l t h b o t h G e n e r a l E l e c t r i c and P r a t t & Whitney o r i g i n a l l y h a v i n g e s s e n t i a l l y p a r a l l e l c o n t r a c t s .

The program c o n s i s t e d of three main a c t i v i t i e s . These were P r o p u l s i o n S y s t e m D e f i n i t i o n , Component T e c h n o l o g i e s , and Systems I n t e g r a t i o n . P r o p u l s i o n S y s t e m D e f i n i t i o n implemented the o r i g i n a l " c l e a n sheet" d e s i g n of a p a p e r e n g i n e , references 2 and 3 . The a c t i v i t y d e f i n e d the o v e r a l l e n g i n e c y c l e and t h e t e c h n o l o g i e s r e q u i r e d t o a c h i e v e it. These p a p e r e n g i n e s , c a l l e d F l i g h t P r o p u l s i o n Systems (FPS) were t o r e p r e s e n t t h e f u l l y developed, p r o d u c t i o n v e r s i o n s of t h e EEE. As component t e c h n o l o g i e s and t e s t r e s u l t s became a v a i l a b l e from t h e rest of the e f f o r t , these FPS p r o p u l s i o n s y s t e m s were u p d a t e d and new p e r f o r m a n c e and f u e l b e n e f i t s c a l c u l a t e d .

The most a g g r e s s i v e t e c h n o l o g i e s i d e n t i f l e d i n t h e I n i t i a l FPS d e s i g n were developed d u r i n g t h e Component Technology e f f o r t . The t e c h n o l o g i e s were e v a l u a t e d t h r o u g h s u b - s c a l e and f u l l - s c a l e r i g tests f o r v e r i f i c a t i o n .

The System I n t e g r a t i o n i n v o l v e d b o t h c o r e and i n t e g r a t e d c o r e / l o w s p o o l t u r b o f a n e n g i n e t e s t i n g . By h a v i n g t h i s e l e m e n t , it was p o s s i b l e t o e v a l u a t e the i n t e r a c t i o n s and t h e o p e r a b i l i t y of the advanced t e c h n o l o g y components i n a c o m p l e t e s y s t e m .

Completion of a l l component and s y s t e m a c t i v i t i e s coupled w i t h t h e f i n a l u p d a t e of t h e FPS computer models would d e f i n e t h e a c t u a l l e v e l of f u e l s a v i n g s achievement of t h e EEE.

Technology r e a d i n e s s was p r o v i d e d by the t e s t i n g and it was t h e n up t o i n d u s t r y t o i n c o r p o r a t e t h i s t e c h n o l o g y i n t o p r o d u c t i o n e n g i n e s .

A s mentioned, t h e s e were o r i g i n a l l y e s s e n t i a l l y p a r a l l e l c o n t r a c t s . I n 1982, f u n d i n g f o r EEE was r e d u c e d and the program had t o be descoped by a b o u t $lgM. G e n e r a l E l e c t r i c , however, was w e l l a l o n g and the v a s t m a j o r i t y o f t h e i r s y s t e m s .

i n t e g r a t i o n c o s t s had a l r e a d y been a c c r u e d . It was t h e r e f o r e decided t o complete t h e G e n e r a l E l e c t r i c program and t e r m i n a t e t h e System I n t e g r a t i o n e f f o r t i n t h e P r a t t 8 Whitney program.

Later i n 1982 a n d 1983 some o f t h e f u n d i n g was r e s t o r e d t o b e used as tvseedtl money f o r a f o l l o w - o n t o t h e EEE. A s a r e s u l t , t h e component t e c h n o l o g y a c t i v i t i e s have been expanded f o r b o t h c o n t r a c t o r s . These e f f o r t s p r i m a r i l y i n c l u d e s h r o u d l e s s , h o l l o w f a n t e c h n o l o g y and a d d i t i o n a l t e s t i n g o f t h e EEE c o m p r e s s o r s . A t t h i s time, no f u n d i n g f o r a follow-on t u r b o f a n program a p p e a r s a v a i l a b l e and t h e t e c h n o l o g y e f f o r t s w i l l be e n d i n g i n 1985.

F i g u r e s 3 and 4 are cut-away t y p e drawinge o f t h e two EEE FPS e n g i n e s . F i g u r e 3 i s t h e G e n e r a l E l e c t r i c EEE which c o n s i s t s of a s i n g l e stage f a n and q u a r t e r stage open b o o s t e r d r i v e n by a f i v e - s t a g e low p r e s s u r e t u r b i n e ; a c o r e c o n s i s t i n g of a 10-stage 2 3 : l p r e s s u r e r a t i o h i g h p r e s s u r e c o m p r e s s o r , d u a l a n n u l a r combustor f o r low e m i s s i o n s , and t w o - s t a g e h i g h p r e s s u r e t u r b i n e ; d a i s y - t y p e m i x e r ; a n d l o n g d u c t n a c e l l e . I n a d d i t i o n , a n e l e c t r o n i c e n g i n e mounted f u e l c o n t r o l , K e v l a r f a n c o n t a i n m e n t , and b u l k a c o u s t i c t r e a t m e n t are a l l u s e d .

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

F i g u r e 4 i s t h e P r a t t & Whitney EEE FPS which c o n s i s t s of a s i n g l e - s t a g e f a n and f o u r - s t a g e low p r e s s u r e compressor

I 4

d r i v e n by a f i v e - s t a g e low p r e s s u r e t u r b i n e ; a c o r e c o n s i s t i n g o f a 10-stage 1 4 : l p r e s s u r e r a t i o high p r e s s u r e c o m p r e s s o r , two zone low e m i s s i o n combustor, and s i n g l e - s t a g e high p r e s s u r e t u r b i n e ; a d a i s y - t y p e m i x e r ; and l o n g d u c t n a c e l l e .

Although t h e c o n f i g u r a t i o n s o f t h e two e n g i n e s are d i f f e r e n t , t h e c y c l e s a r e q u i t e similar w i t h ~ 3 8 : i o v e r a l l p r e s s u r e r a t i o , ru1350°C (2450 OF) t u r b i n e r o t o r i n l e t t e m p e r a t u r e , and r u 6 . 8 : 1 b y p a s s r a t i o .

These two rrpaperrr e n g i n e s r e a l l y r e p r e s e n t t h e o u t p u t o f t h e EEE program w i t h t h e i r component performance and t e c h n o l o g y a s s u m p t i o n s proven by t h e EEE t e s t i n g .

MAJOR TECHNOLOGY DEVEL9PMENTS F O R FUEL EFFICIENCY Because t h e s u b j e c t i s p r i m a r i l y f u e l e f f i c i e n c y , o n l y t h o s e t e c h n o l o g i e s which c o n t r i b u t e d s i g n i f i c a n t l y t o r e d u c e d f u e l consumption have been s e l e c t e d f o r t h i s review. F u l l d e s c r i p t i o n o f t h e EEE w i l l b e a v a i l a b l e when t h e f i n a l r e p o r t s f o r t h e c o n t r a c t s are completed.

Fan

-

H i g h l i g h t e d i n f i g u r e 5 i s t h e G e n e r a l E l e c t r i c EEE f a n (ref. 4 ) . T h i s s i n g l e - s t a g e f a n c o n s i s t s of 32 low aspect r a t i o b l a d e s f o l l o w by a q u a r t e r - s t a g e b o o s t e r f o r . t h e c o r e .

The d e s i g n b y p a s s r a t i o i s 6.8 a t a 1.65 pressure r a t i o and 400 m/sec (1315 f t / s e c ) t i p speed. F u e l e f f i c i e n c y t e c h n o l o g i e s i n c l u d e t h e r e d u c e d number o f b l a d e s w i t h .55 s p a n , aft-mounted dampers t o r e d u c e l o s s e s . The q u a r t e r s t a g e b o o s t e r a c h i e v e d a 1.67 p r e s s u r e r a t i o f o r t h e c o r e w i t h m o d e r a t e hub l o a d i n g . The r e s u l t was a f a n w i t h 89.2 p e r c e n t b y p a s s and 89.5 p e r c e n t c o r e e f f i c i e n c i e s .

The q u a r t e r - s t a g e open b o o s t e r a l s o p r o v i d e d a second f u e l s a v i n g s t e c h n o l o g y which i s a c e n t r i f u g a l c l e a n i n g a c t i o n on t h e c o r e flow. With t h i s d e s i g n , most d u s t and d i r t are thrown outward and n o t i n g e s t e d by t h e c o r e . T h i s g r e a t l y r e d u c e s f o r e i g n o b J e c t i n g e s t i o n and t h u s e r a s i o n e f f e c t s on t h e compressor blade l e a d i n g e d g e s .

F i n a l l y , a n i n t e g r a l vane-frame w i t h wide s p a c i n g between t h e r o t o r and s t a t o r v a n e s was u s e d f o r r e d u s e d weight and r e d u c e d n o i s e g e n e r a t i o n .

Compressors Shown i n f i g u r e 6 are b o t h h i g h pressure c o m p r e s s o r s .

One o f the f u e l s a v i n g t e c h n o l o g i e s f o r t h e EEE i s t o p r o v i d e b e t t e r a c t i v e and p a s s i v e t i p c l e a r a n c e c o n t r o l . S i g n i f i c a n t g a i n s were made on t i p c l e a r a n c e c o n t r o l by u s i n g a s h o r t s t i f f c o r e d e s i g n . The s h o r t e r c o m p r e s s o r s were o b t a i n e d by p r o v i d i n g h i g h e r p r e s s u r e r a t i o p e r s t a g e t h e r e b y r e d u c i n g t h e t o t a l number of s t a g e s . The G e n e r a l E l e c t r i c a p p r o a c h , r e f e r e n c e 4 , shown on t h e l e f t s i d e o f f i g u r e 6, i s a 1 0 - s t a g e 2 3 : l p r e s s u r e r a t i o d e s i g n . T h i s h i g h p r e s s u r e r a t i o was a c h i e v e d through h i g h s p e e d rather t h a n h i g h l o a d i n g . Endwall c o n t o u r i n g was used t o minimize w a l l l o s s e s . To a v o i d problems of comparing e f f i c i e n c i e s f o r c o m p r e s s o r s w i t h d i f f e r e n t p r e s s u r e r a t i o s , p o l y t r o p i c e f f i c i e n c y i s q u o t e d .

For t h i s compressor, a 90.5 p e r c e n t p o l y t r o p i c e f f i c i e n c y was o b t a i n e d . For improved d u r a b i l i t y , t h e f r o n t s t a g e s u s e a ~ .

low aspect ratio blade design improving foreign object ingestion tolerance.

On the right in figure 6, is the Pratt & Whitney 10-stage 14:l pressure ratlo compressor, reference 5. This highly loaded compressor uses advanced aerodynamics and controlled percent polytropic diffusion airfoils for a very high 91.5 efficiency. It uses only half the number of blades of the existing JTgD engines. Eliptic leading edges were used for improved erosion resistance. This compressor is lower in pressure ratio s o that it could be driven by a single-stage turbine.

Both compressors use active clearance control on the last several stages. The active clearance control was used to minimize clearances during cruise, maximizing efficiency, but would allow maximum clearance during take-off to reduce 6. This helps maintain their chances for tip wear, reference high efficiency over the life of an engine.

Tur b ine s The EEE represented Pratt & Whitney's first opportunity to use a single-stage high pressure turbine, reference 5. The main features of this turbine are shown in figure 7. This turbine used advanced transonic aerodynamics to yield a high 88.5 percent. This efficiency design for a single stage of high efficiency coupled with the reduced weight and parts count had a significant lmpact on reducing direct operating cost for the Pratt & Whitney EEE. To permit higher temperatures with reduced cooling, single crystal airfoils and c e r a m i c c o a t e d o u t e r a i r s e a l s were u s e d . A c t i v e c l e a r a n c e c o n t r o l was a l s o used t o m a i n t a i n t i g h t c l e a r a n c e s f o r t h e c r u i s e p o r t i o n of o p e r a t i o n .

Not shown is t h e G e n e r a l E l e c t r i c two-stage high pressure t u r b i n e which a c h i e v e d a 92.5 p e r c e n t e f f i c i e n c y . Ceramic t i p s e a l s , a c t i v e c l e a r a n c e c o n t r o l and advanced aerodynamics were used t o a c h i e v e t h i s h i g h e f f i c i e n c y .

Both low p r e s s u r e t u r b i n e s used advanced aerodynamics and a c t i v e c l e a r a n c e c o n t r o l t o a c h i e v e high e f f i c i e n c i e s .

I n summary, f o r a l l t h e t u r b i n e s , a t l e a s t one p o i n t improvement i n e f f i c i e n c y was o b t a i n e d o v e r mid 1 9 7 0 ' s t e c h n o l o g y .

Mixers Both EEE e n g i n e s used m i x e r s and l o n g d u c t n a c e l l e s , r e f e r e n c e s 5 and 7. I n both c a s e s t h e m i x e r s c o n t r i b u t e d a b o u t 1 / 5 o f t h e t o t a l f u e l s a v i n g s b e n e f i t s f o r t h e EEE.

Both E E E ' s l l d a l s y - t y p e l l e x h a u s t g a s mixers are shown i n a s i d e view i n t h e upper l e f t of f i g u r e 8, G e n e r a l E l e c t r i c ' s r e f e r e n c e 8, i s t h e u p p e r and P r a t t & W h i t n e y ' s I s t h e lower.

The u p p e r r i g h t of f i g u r e 8 shows t h e p r o g r e s s i o n of m i x e r e x p e r i e n c e from t h e a 1:l bypass e n g i n e t h r o u g h a series of t h r e e model t e s t s . I n t h e end, b o t h m i x e r des:gns p r o v i d e d a b o u t t h e same b e n e f i t . F o r -7:l b y p a s s r a t i o t u r b o f a n e n g i n e s , these m i x e r s p r o v i d e a b o u t 3 p e r c e n t f u e l s a v i n g s benef it.

The bottom l e f t s e c t i o n of f i g u r e 8 g i v e s t h e o v e r a l l d e s i g n c h a r a c t e r i s t i c s f o r both m i x e r d e s i g n s . Both a r e s c a l l o p e d 1 8 l o b e d e s i g n s . The main d i f f e r e n c e is t h e p e n e t r a t i o n of t h e l o b e s i n t o t h e f a n s t r e a n . Higher p e n e t r a t i o n y i e l d s b e t t e r mixing b u t a l s o higher p r e s s u r e l o s s e s .

Exhaust gas m i x e r s r e q u i r e t h e u s e of long d u c t n a c e l l e s . Nacelle l o c a t i o n s were e v a l u a t e d i n model tests where i n s t a l l a t i o n s w i t h a n e t b e n e f i t were found t h e r e b y a v o i d i n g t h e p e n a l t y normally a s s o c i a t e d w i t h such n a c e l l e s .

INTEGRATED SYSTEM EVALUATION A s s t a t e d e a r l i e r t h e G e n e r a l E l e c t r i c c o n t r a c t was n o t t e r m i n a t e d when f u n d i n g was c u t back. T h e r e f o r e , G e n e r a l E l e c t r i c ' s EEE went t h r o u g h t h e s y s t e m s i n t e g r a t i o n e v a l u a t i o n which i n c l u d e d b o t h c o r e e n g i n e t e s t s and f u l l y I n t e g r a t e d c o r e and low s p o o l ( I C L S ) t u r b o f a n t e s t s . These e n g i n e c o n f i g u r a t i o n s had f u l l aerodynamic e q u i v a l e n c y w i t h t h e i r c o r r e s p o n d i n g p a r t s of the EEE FPS. The hardware was a l s o f l i g h t w e i g h t i n t h e gas p a t h b u t o t h e r hardware such as e n g i n e c a s e s , g e a r b o x , e t c . , was b o i l e r p l a t e . Also, f o r t h e t u r b o f a n c o n f i g u r a t i o n , a bell-mouth i n l e t was used f o r t h e ground t e s t and t h e n a c e l l e had o n l y i n t e r i o r aerodynamic s u r f a c e s .

F i g u r e 9 i s a photograph of t h e t u r b o f a n e n g i n e I n t h e t e s t s t a n d a t G e n e r a l E l e c t r i c ' s Peebles, Ohio, t e s t s i t e .

A l l t h e f u e l s a v i n g component t e c h n o l o g i e s were i n c l u d e d i n t h i s e n g i n e and e x e r c i s e d d u r i n g t h e ground t e s t i n g . While on t e s t , t h i s u n i q u e e n g i n e a c h i e v e d o v e r 162,360 N (36,500 l b f ) t h r u s t . When t h e e n g i n e d a t a is c o r r e c t e d f o r i n s t a l l a t i o n , instrumentation, and flight vs. ground effects, the research engine is projected to have a cruise specific fuel consumption 0.056 kg/hr-N (.55 lbm/hr-lbf), uninstalled. Corrected for of installation, the projected cruise specific fuel consumption would be 13.5 percent better than the baseline average production CF6-50C. That would make this set of research hardware the world's most fuel efficient turbofan engine.

F U E L SAVINGS SUMMARY Figure 10 summarizes the results of the program. If all EEE technologies were applied to a new engine and the the cycle and configuration of that engine optimized for today's $0.264/liter ($l.OO/gallon) fuel prices, the benefits of the EEE would be 17-19% in fuel savings. If the commercial fleet could obtain half this benefit, it would translate in to nearly 4 billion liters (1 billion gallons) of jet fuel saved each year. (Currently more than 38 billion liters (10 billion A ten percent gallons) of jet fuel are burned each year.)

reduction in direct operating cost would also be realized along with acoustic and environmental improvements.

The fuel savings are achieved through the four main areas shown in the pie chart in figure 10. Improved components using advanced aerodynauics, active clearar.2.e control, reduced gas-path leakage, higher temperature materials, and reduced cooling flows account for about half of the fuel savings. The higher pressure, temperature, and bypass ratio cycle accounts for approximately a quarter of the benefit. The efficient m i x e d f l o w exhaust a c c o u n t s f o r a b o u t a f i f t h and t h e improved n a c e l l e i n s t a l l a t i o n , t h e remainder.

TECHNOLOGY APPLICATION A s t h e EEE program was p r o g r e s s i n g , b o t h General E l e c t r i c a n d P r a t t & Whitney saw immediate b e n e f i t f o r t h e EEE t e c h n o l o g y . So even b e f o r e t h e EEE c o n t r a c t s are o f f i c i a l l y c o m p l e t e , w e f i n d a p p l i c a t i o n of t h e EEE t e c h n o l o g i e s o c c u r i n g . Without g e t t i n g i n t o s p e c i f i c d e t a i l s , f i g u r e 11 i n d i c a t e s t h e numbers of t e c h n o l o g y a p p l i c a t i o n s as a p p l i e d t o new and d e r i v a t i v e h i g h bypass t u r b o f a n s of both companies.

What c o u n t s as a t e c h n o l o g y f o r f i g u r e 11 would be items l i k e f a n and compressor t i p t r e n c h e s , h i g h compressor b l a d e l o a d i n g , improved compressor aerodynamic d e s i g n t o o l s , c o m p r e s s o r vane uncambering a t e n d w a l l s , e t c . T a b l e s I a n d I1 p r o v i d e t h e complete l i s t t h a t went i n t o f i g u r e 11.

It can be claimed % h a t a p p r o x i m a t e l y half of the f u e l s a v i n g s b e n e f i t s of t h e PW2037 are a t t r i b u t a b l e t o t h e EEE program. A s b o t h companies d e v e l o p e n g i n e s s u c h as t h e PW4000 and t h e CF6-80C2, s u b s t a n t i a l p o r t i o n s of t h e i r f u e l s a v i n g s b e n e f i t s can be a t t r i b u t e d t o t e c h n o l o g y developments i n i t i a t e d by t h e EEE. G e n e r a l E l e c t r i c has a l s o i d e n t i f i e d a s u b s t a n t i a l number of t e c h n o l o g i e s t h a t are a p p r o p r i a t e f o r t h e i r m i l i t a r y p r o d u c t s and are i n c o r p o r a t i n g them.

THE FUTURE When f u n d s were r e s t o r e d i n 1983, it was d e c i d e d t o u s e some of t h e f u n d s t o e v a l u a t e t u r b o f a n e n g i n e t e c h n o l o g i e s and c y c l e s of t h e f u t u r e b u i l d i n g upon t h e EEE. The s t u d i e s would h a v e a n o u t p u t similar t o t h e i n i t i a l EEE s t u d y , t h a t is a d e f i n i t i o n of a complete t u r b o f a n p r o p u l s i o n s y s t e m , b u t f o r t h e y e a r s 2000-2010. The s t u d i e s would t r y t o answer i f t u r b o f a n t e c h n o l o g y I s an area of f ~ d i m i n l s h i n g r e t u r n s " and, i f n o t , e s t a b l i s h t h e b a s i s f o r a follow-on program a f t e r EEE.

F i g u r e 1 2 I s t h e r e s u l t of t h e Pratt & Whitney s t u d y c a l l e d t h e "Target Engine". P r a t t & Whitney used t e c h n o l o g y e x t r a p o l a t i o n s and l i m i t e d p a r a m e t r i c c y c l e m a l y s e s t o a r r i v e a t t h i s c o n c e p t u a l e n g i n e . The T a r g e t Engine has a g e a r - d r i v e n swept b l a d e N 1 2 : l bypass r a t i o f a n and s e p a r a t e f l o w e x h a u s t . ( A m i x e r b e n e f i t a t rn 1 2 : 1 bypass r a t i o c o u l d n o t be i d e n t i f i e d . ) The o t h e r major impact i s t h e h i g h , ~ 6 0 : 1 , c y c l e p r e s s u r e r a t i o which r e q u i r e s small and h i g h t e m p e r a t u r e rear s t a g e s of t h e h i g h p r e s s u r e compressor.

Because of t h e Improved ( a p p r o x i m a t e l y one p o i n t p o l y t r o p i c ) c o m p r e s s o r e f f i c i e n c y , o n l y a modest r i s e i n t u r b i n e r o t o r i n l e t t e m p e r a t u r e of a p p r o x i m a t e l y one hundred d e g r e e s is r e q u i r e d .

The b a s i c t e c h n o l o g i e s r e q u i r e d are advanced, c o n t r o l l e d d i f f u s i o n , h i g h e r e f f i c i e n c y c o m p r e s s o r ; low p r e s s u r e d r o p d i f f u s e r - c o m b u s t o r ; h i g h a n n u l u s - s p e e d - s q u a r e d , f u l l t h r e e - d i m e n s i o n a l d e s i g n t u r b i n e s ; c l o s e d - l o o p a c t i v e c l e a r a n c e c o n t r o l ; c o m p o s i t e i n t e g r a t e d s t r u c t u r e s ; s h o r t , s h o c k - f r e e i n t e g r a t e d f a n cowl; a s w e p t , s h o c k - f r e e f a n ; a n d h i g h e f f i c i e n c y r e d u c t i o n g e a r .

When t h i s t y p e of e n g i n e is e v a l u a t e d , t h e p o t e n t i a l f u e l s a v i n g s i s 15.5 p e r c e n t I n c r u i s e s p e c i f i c f u e l consumption 1 2 o v e r t h e EEE. T h i s t r a n s l a t e s t o a 2 4 p e r c e n t s a v i n g s I n f u e l burned f o r a 3700 km (2000 n a u t i c a l m i l e ) m i s s i o n 500 p a s s e n g e r q u a d j e t . These b e n e f i t s are s p l i t r o u g h l y e q u a l l y between thermal e f f i c i e n c y improvements and p r o p u l s i v e e f f i c i e n c y improvements. Because of t h e c o n t r i b u t i o n s of t h e swept f a n t o the e f f i c i e n c y improvements, some p r e l i m i n a r y d e s i g n s t u d i e s have been started u s i n g EEE f u n d s .

To p u t a l l t h e EEE and t h e f u t u r e i n t o one p e r s p e c t i v e , f i g u r e 13 is p r o v i d e d . T h i s f i g u r e shows the t r e n d of u n i n s t a l l e d , bare s p e c i f i c f u e l consumption s t a r t i n g w i t h t h e JT3 t y p e t u r b o j e t as a f u n c t i o n of year of i n i t i a l c e r t i f i c a t i o n . The n e x t s p o t on the c u r v e is t h e JT3D/JT8D t y p e e n g i n e s w i t h a b o u t a 15 p e r c e n t improvement. The n e x t s p o t , t h e f i r s t JT9D/CF6 t y p e h i g h bypass e n g i n e s , a g a i n made a s u b s t a n t i a l improvement on t h e o r d e r of 1 9 p e r c e n t o v e r t h e p r e v i o u s e n g i n e s . N e x t comes t h e PW2037 w i t h an improvement on t h e o r d e r o f 1 2 p e r c e n t o v e r t h e JT9D/CF6. The PW2037 r e p r e s e n t s t h e f i r s t s i g n i f i c a n t u s e of EEE t e c h n o l o g y .

Two s p o t s f o r EEE are shown. The h i g h e r is a b o u t 1 5 p e r c e n t below t h e JT9D/CF6 s p o t and r e p r e s e n t s t h e f i n a l r e s u l t s f o r t h e EEE FPS e n g i n e s . The lower s p o t r e p r e s e n t s a p p l i c a t i o n of EEE t e c h n o l o g i e s b u t w i t h some r e - o p t i m i z a t i o n of t h e e n g i n e c o n f i g u r a t i o n such as t h e number of compressor and t u r b i n e s t a g e s . It is about 1 8 p e r c e n t below t h e JTgD/CF6 s p o t . The Turbofan F u t u r e P o t e n t i a l s p o t r e p r e s e n t s t h e r e s u l t s of t h e Target Engine s t u d y j u s t shown, a g a i n showing t h a t s u b s t a n t i a l g a i n s ere s t i l l p o s s i b l e . T h i s is v e r y i m p o r t a n t because it is n o t c l e a r t h a t t u r b o p r o p s w i l l be a v a i l a b l e i n the h i g h t h r u s t s i z e n o r m a l l y f i l l e d by t u r b o f a n s d u r i n g t h i s time p e r i o d .

F i n a l l y , are two s p o t s f o r advanced p r o p f a n t y p e t u r b o p r o p s y s t e m s which i n c l u d e advanced t e c h n o l o g y c o r e s .

The higher s p o t u s e s an EEE t e c h n o l o g y c o r e and low p r e s s u r e t u r b i n e and t h e lower s p o t u s e s the a d v a n c e d Target Engine c o r e and low p r e s s u r e t u r b i n e t e c h n o l o g i e s . Thus even t h e p r o p f a n g a i n s s u b s t a n t i a l l y from t u r b o f a n c o r e t e c h n o l o g y developments.

C ONC LU S I O N S The EEE program was h i g h l y s u c c e s s f u l and p r o v i d e s an e x c e l l e n t t e c h n o l o g y base f o r much improved t u r b o f a n e n g i n e f u e l e f f i c i e n c y . As a r e s u l t , b o t h G e n e r a l E l e c t r i c and P r a t t & Whitney a r e r a p i d l y t r a n s l a t i n g these t e c h n o l o g i e s i n t o t h e i r p r o d u c t s making the EEE program a g r e a t s u c c e s s .

Although no f u n d i n g has been i d e n t i f i e d , a f o l l o w - o n t u r b o f a n r e s e a r c h program c o u l d o b t a i n s u b s t a n t i a l a d d i t i o n a l f u e l s a v i n g s b e n e f i t s . The c o r e p o r t i o n of these t e c h n o l o g i e s would have d i r e c t a p p l i c a t i o n t o p r o p f a n t u r b o p r o p p r o p u l s i o n s y s t e m s p r o v i d i n g s u b s t a n t i a l b e n e f i t t o them a l s o .

TABLE I

P W E 3 TECHNOLOGIES - APPLICATION TO COMMERCIAL ENGINES

TECHNOLOGY IT9D-7R4 PW2037 PW4000 e_ - :OMPRESSOR INTERMEDIATE CASE WITH THROUGH STRUTS X :AN AND COMPRESSOR T I P TRENCHES X X X (EDUCED LPC INNER CAVITY VOLUMES X X X .ow C X I U L c )RUM COMPRESSOR ROTORS WITH INTEGRAL K N I F E EDGES X X X :OMPRESSOR A I R F O I L S WITH E L L I P T I C A L LEADING EDGE X I I N I SHROUDED HPC X X X MUBLE WALL COMPRESSOR ACTIVE CLEARANCE CONTROL :ONTROLLED DIFFUSION COMPRESSOR A I R F O I L S X X [NCREASED COMPRESSOR STAGE LOADINGS X X X rANGENTIAL COMPRESSOR BLADE ATTACHMENTS X :ANTED COMPRESSOR E X I S T GUIDE VANE/DIFFUSER X rwo B E A R I N G HIGH SPOOL WITH DAMPING AND SPRINGS X X ION-METALLIC TURBINE OUTER AIRSEAL X X X %LL RING TURBINE SIDEPLATES IMPROVED TURBINE FEATHERSEAL SLOTS X X X MERMAL BARRIER COATING ON TURBINE VANE PLATFORM X IMPROVED GASPATH STATIC SEALS X X rURBINE A I R F O I L INTERNAL T R I P STRIPS X X rURBINE A I R F O I L INTERNAL TURNING VANES X X 3-D DESIGN TURBINE VANES X [MPROVED SUCTION S I D E F I L M COOLING X i I G H AN2 TURBINE X X X r H I N TURBINE A I R F O I L T R A I L I N G EDGES i I G H STAGE LOADING TURBINE AIRFOILS X X X X U G H REACTION HP TURBINE LOW CX/U TURBINE X X X X TURBINE A I R F O I L S WITH E L L I P T I C A L LEADING EDGES TWIST RESTRAINED HP TURBINE VANES X X BOLTLESS TURBINE D I S K S I D E PLATE X LP TURBINE FLOW GUIDES X X X X LOW LOSS CONTOUR TURBINE E X I T GUIDE VANE X THREE BEARING LOW SPOOL X TABLE I 1

6 E E 3 TECHNOLOGIES - APPLICATION TO COMMERCIAL/MILITARY ENGINES

-

-

I\OWTH F6-80C2 'FM 56-3 110 TECHNOLOGY

-

-

X IMPROVED COMPRESSOR AERODYNAMIC DESIGN TOOLS :OMPRESSOR VANE UNCAMBERING AT ENDWALLS X X IMPROVED BETWEEN SHINGLE SEALS FOR SHINGLE COMBUSTOR LINERS X tEDUCE0 THROUGH-FLOW VELOCITY HP TURBINE DESIGN YIGH STAGE REACTION HP TURBINE IMPROVED HP TURBINE FLOWPATH OVERLAPS HP TURBINE CONVERGED STATOR BANDS X HP TURBINE IMPROVED A I R F O I L SURFACE VELOCITY DISTRIBUTIONS X X CERAMIC HP TURBINE SHROUDS LIGHTWEIGHT RADIAL STRUTTED TURBINE FRAME WITH POLYGONAL CASING IMPROVED LP TURBINE FLOWPATH OVERLAP: IMPROVED LP TURBINE A I R F O I L SURFACE VELOC I T Y DISTRIBUTIONS X FADEC FAULT I N D I C A T I O N AND CORRECTIVE ACTION SYSTEM

- -

REFERENCES 1. ETHELL, J. L. (19831, Fuel Economy In Aviation, NASA SP-462 2.

JOHNSTON, R. P., et. al. (19801, Energy Efficient Engine -

Flight Propulsion System Preliminary Analysis and Design (General Electric), NASA CR-159583

GARDNER, W. B. (19791, Energy Efficient Engine - Flight

3 .

Propulsion System Preliminary Analysis and Design (Pratt & Whitney), NASA CR-159487 4. SULLIVAN, T. J. and HAGER, R. D. (1983), The Aerodynamic Design and Performance of the General Electric/NASA E3

- Fan, AIAA-83-1160

GARDNER, W. B. (1982), Energy Efficient Engine (E3) 5.

Technology Status, AIAA-82-1052 6. BEITLER, R. S., SAUNDERS, A. A . , and WANGER, R. P. (1980), Fuel Conservation Through Active Control of Rotor Clearances, AIAA-80-1087 KUCHAR, A. P., and CHAMBERLIN, R. (19841, Comparison of 7.

Full-scale Engine and Subscale Model Performance of a Mixed Flow Exhaust System for an Energy Efficient Engine Propulsion System, AIAA-84-0283 Figure 1 . - Overview of aircraft energy efficiency program.

CALENDAR YEAR

77 I 78 I 79 [ 80 I 81 I 82 I 83 I 84 I 85

’ FLIGHT PROPULSiON SYSTEM DESIGN I I I I I I PROPULSION SYSTEM DEFINITION (Ir UPDATES COMPONENT TECHNOLOGIES SYSTEMS INTEGRATION TECHNOLOGIES ICLS - INTEGRATED COREILOW SPOOL GENERAL ELECTRIC

0 PRATT (IrWHITNEY

Figure 2. - Energy efficient engine program.

I- TWO-ZONE COMBUSTOR I/4-STAGE ISLAND BOOSTER7 \

\ 1 rFIVE-STAGE L. P. TURBINE

SINGLE-STAGE FAN 7 I \ I \ \ I ' \ ; LlWO-STAGE H. P. TURBINE TEN-STAGE H. P. COMPRESSORJ CS-80-2098 Figure 3. - Energy efficient engine, General Electric configuration.

FOUR-STAGC L P. COMPRESSOR1 ,-TWO-ZONE COMBUSTOR I I I SINGLE-STAGE FAN 7 I ,-FOUR-STAGE L . P. TURBINE I I I 1 t I ,-MIXER ! !

f SINGLE-STAGE H. P. TURBINE TEN-STAGE H. P. COMPRESSOR' c s -80-2099 Figure 4 - Energy efficient engine, Pratt & Whitney configuration.

32 BLADE / 6.8 BYPASS RATIO / 1.65 PRESSURE RATIO 0.55 SPAN, AFT MOUNTED LOW LOSS SHROUD 89.2 BYPASS, 89.5 CORE EFFICIENCY I FOD SEPERATION QUARTER STAGE BOOSTER / WIDE ROTOR-STATOR SPACING INTEGRAL STATOR-FAN FRAME Figure 5. - EEE fan technology.

(a) General Electric. 10-stage; 23: 1 p r e s s u r e ratio; High speed, endbend treatment; 90.5 poly. eff.

(b) Pratt & Whitney. 10-stage; 14: 1 p r e s s u r e ratio; High loading controlled diffusion; 91.5 poly. eff.

Figure 6 . - EEE compressor technology; Active and passive clearance c o n t r o l ; short, stiff rotor; low aspect ratio blades.

i

. . . .

g 3.0 GE P&w

r

GE RATIO

m PHASE

PHASE P & W L n a

iii

MID 70’s 1978 1980 1981183 TECHNOLOGY READINESS FEATURES GE P & W NEW E3 TECHNOLOGY 0 NUMBER OF LOBES 18 18 0 SHORT EFFICIENT MIXERS COMBINING PENETRATION, % 45 15 HIGH MIXING EFFECTIVENESS WITH LCVY 0 MIXING LENGTH, L I D .52 .61 PRESSURE LOSS 0 MIXING EFFECTIVENESS, % 79 85 0 MIXERS AT HIGH BYPASS RATIOS 0 REDUCED WEIGHT MIXER DESIGNS Figure 8. - EEE exhaust mixer technology.

Figure 9. - EEE experimental engine o n test stand.

I I I " I REFERENCE ENGINE ENERGY EFFICIENT ENGINE 18% FUEL SAVINGS OPR: 25-30 OPR 36-37 BPR. 4.3.5.3 BPR: 6 6 - 6 8 T (SLTO1' 2300~2400'F 1 (SLTO)' 2450 - 250dF SOURCES OF FUEL SAVINGS IMPROVED COMPONENTS -, ,- IMPROVED CYCLE ,/ HIGHER PRESSURE RATIO ADVANCED AERODYNAMICS .\ I HIGHER BYPASS RATIO ACTIVE CLEARANCE CONTROL I HIGHER TEMPERATURES REDUCED GAS-PATH LEAKAGE HIGHER TEMPERATURE MATERIALS REDUCED COOLING , .

.

.

I IMPROVED NACELLE INSTALLATION '..- MIXED FLOW EXHAUST Figure 10. - EEE benefits summary.

c-79-2745 I APPLICATION I CF6-8OC2 I CFM56-3 1 MILITARY I NUMBER OF 9 6 15 TECHNOLOG I ES (a) General Electric.

C-79-2743 APPLICATION JT9D-7R4 PW 2037 PW 4ooo NUMBER OF 7 28 30 TECHNOLOGIES ADVANCED TECHNOLOGY REQUIREMENTS FOR M00-2010A. D . TURBOFAN SYSTEMS ADVANCED CYCLE 55-65 OVERALL PRESSURE RATIO 9-12 BYPASS RATIO 2700-2800 F COMBUSTOR EXIT TEMPERATURE SEPARATE EXHAUSTS LOW A P I P DIFFUSERCOMBUSTOR ~ ,-HIGH AN^, FULLY \ ADVANCED CONTROLLED /’ 3-D DESIGN TURBINES \\ DIFFUSION COMPRESSOR 7% \ .A.

.I‘ -- SWEPT FAN -- ‘-CLOSED LOOP ACTIVE CLEARANCE CONTROL \ # ‘\-SHORT, SHOCK-FREE ’+\, INTEGRATED COWL ’\ ‘-COMPOSITE, INTEGRATED STRUCTURE Figure 1 2 . -Advanced turbofan research requirements and benefits. Potential fuel savings w e r EEE -15.5% SFC, -24% fuel burned.

- CERTIFIED TURBOJETS .9 - .8 CERT. LOW-BYPASS FANS e -TECHNOLOGY TREND v , W - c e .7 n CERT. HI-BYPASS FANS Y J - $ , . 6 ENERGY EFFICIENT ENGINE z 3 - . 5 Q TURBOFAN FUTURE POTENTIAL

TURBOPROPS 6

I I 1 I 0 ADVANCED TURBOPROPS . 4 * Figure 13. -Turbofan technology trend.

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.

NASA TM-83741 4. Title and Subtitle 5. Report Date Energy E f f i c i e n t Engine Program C o n t r i b u t i o n s t o A i r c r a f t F u e l C o n s e r v a t i o n 6. Performing Organization Code 505-40-12C 7. Author(s) 8. Performing Organization Report No.

P e t e r G. B a t t e r t o n E-2226 10. Work Unit No.

9. Performing Organization Name and Address N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n 11. Contract or Grant No.

Lewis Research Center C l e v e l a n d , Ohio 44135 13. Type of Report and Period Covered 12. Sponsoring Agency Name and Address T e c h n i c a l Memorandum N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n 14. Sponsoring Agency Code Washington, D.C. 20546 17. Key Words (Suggested by Author(s) ) 18. Distribution Statement Energy C o n s e r v a t i o n Subsonic T r a n s p o r t T u r b i n e Engine U n c l a s s i f i e d - u n l i m i t e d A i r c r a f t T u r b i n e Engine STAR C a t e g o r y 07 Energy E f f i c i e n t Engine 22. Rice' 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. NO. of Pages U n c l a s s i f i e d U n c l a s s i f i e d * For sale by the National Technical Information Service, Springfield, Virginia 22161