Document
N 8 4 - 2 4 5 8 1
NASA Technical Memorandum 83641
Supersonic STOVL Ejector Aircraft from a
Propulsion Point of View
R. Luidens, R. Plencner, W . Haller, and A. blassman
Lewis Research Center
Cleveland, Ohio
Prepared for the
Twentieth Joint Propulsion Coiiference
cosponsored by the AIAA, SAE, and ASME
Cincinnati, Ohio, June 11-13, 1984
i I SUPERSONIC STOVL EJECTOR AIRCRAFT FROH A PROPULSION POINT O F V I E W R h i d e n s , * R. Plencner,** W. Hailer.** and A Glassman+ N a t i o n a l Aeronautics and Space A d m i n i s t r a t i o n Lewis Research Center Cleveland, Ohio A b s t r a c t 1 Higher p r o p u l s i o n system t h r u s t f o r g r e a t e r l i f t - o f f a c c e l e r a t i o n .
The paper f i r s t describes a b a s e l i n e super- sonic STOVL e j e c t o r a i r c r a f t , i n c l u d i n g i t s 2 Cooler f o o t p r i n t , f o r safer, more p r o p u l s i o n and t y p i c a l o p e r a t i n g modes, and convenient handllng, and lower o b s e r v a b i l i t y i d e n t i f t e s Important p r o p u l s i o n parameters Then a number o f p r o p u l s i o n system changes a r e 3. A l t e r n a t t v e b a s i c p r o p u l s i o n c y c l e s evaluated i n terms o f improving t h e l i f t - o f f performance; namely, a f t d e f l e c t i o n o f t h e e j e c - The approach o f t h i s paper i s t o use t h e t o r j e t and h e a t i n g o f t h e e j e c t o r primary a i r a i r c r a f t o f reference 5 as a baseline. and then e i t h e r by b u r n i n g o r u s i n g t h e h o t englne c o r e t o consider some candidate p r o p u l s i o n system f l o w The p o s s i b i l i t y f o r c o o l i n g t h e f o o t p r i n t growth o p t i o n s The v e h i c l e described i n r e f e - i s i l l u s t r a t e d f o r t h e cases o f m i x i n g o r l n t e r - rence 5 was s e l e c t e d on t h e basis o f d e t a i l e d changlng t h e f a n and core flows, and u s l n g a a l r c r a f t design and performance analyses The c o r e f l o w e j e c t o r F l n a l l y , t h e a p p l l c a t i o n o f present paper analyses t h e p r o p u l s i o n system a new englne concept l s presented, t h e t u r b l n e o p t i o n s from a fundamental p o i n t o f view and bypass engine p l u s a turbocompressor t o supply does n o t I n v o l v e d e t a i l e d design o r t h e evalua- t h e e j e c t o r primary a i r , and t h r u s t d u r i n g take- t i o n o f such f a c t o r s as weights, a i r c r a f t - o f f and combat p r o p u l s i o n i n t e g r a t i o n , and costs Any selec- t l o n from t h e candidate growth o p t i o n s w i l l depend on f u r t h e r d e t a i l e d s t u d i e s I n t r o d u c t i o n It i s g e n e r a l l y accepted t h a t s h o r t t a k e o f f Baseline E j e c t o r A i r c r a f t and v e r t i c a l l a n d l n g (STDVL) a i r c r a f t have an i m p o r t a n t p l a c e i n t h e m l l l t a r y The B r l t l s h The b a s e l i n e e j e c t o r a i r c r a f t and p r o p u l s i o n b u i l t H a r r l e r , a subsonic a i r c r a f t . i s used by system I s descrlbed f i r s t B r l t a l n , Spain, I n d l a , and t h e U S Marines The Russlans a l s o have a subsonic VTOL a i r c r a f t , E l e c t o r Types t h e Forger, f o r use on small a i r c r a f t c a r r l e r s Even having p l c k e d an e j e c t o r type a i r c r a f t , The next generation o f STOVL a i r c r a f t I s t h e r e a r e f i v e types o f e j e c t o r s l i s t e d on t h e expected t o have a t l e a s t supersonlc dash capa- l e f t s i d e o f f t g u r e 3 t h a t could be considered b l l i t y There a r e many candldate c o n f i g u r a t i o n s They f a l l i n t o two c a t e g o r i e s - those w l t h modest b u t f o u r o f t h e l e a d l n g f o r a follow-on a i r c r a f t , prlmary pressure r a t i o s and subsonic secondary contenders a r e shown i n f i g u r e s 1 and 2 They flow, and those wtth a h l g h prlmary pressure a r e - (1) t h e Remote Augmented L l f t System (RALS) r a t i o Those w i t h t h e modest prlmary pressure (which i s taken t o I n c l u d e t h e t u r b l n e bypass r a t l o are: (1) those w l t h steady f l o w and f l x e d englne w i t h turbocompressor u n i t ) , 2 ' ( 2 ) t h e prlmary nozzles, ( 2 ) those w i t h low speed Tandem o r H y b r i d Fan,4 (3) t h e E j e c t o r , and (4) r o t a t l n g prlmary nozzles, and (3) those w i t h t h e Deflected Thrust System, such as, an pulsed f l o w p r i m a r l e s Those w i t h t h e h l g h advanced H a r r i e r w l t h f a n a i r b u r n i n g primary pressure r a t i o are: (4) those having supersonlc secondary flow, and ( 5 ) two stage The present paper deals w i t h t h e E j e c t o r e j e c t o r s D i f f u s e r blowlng f o r g r e a t e r d l f f u - c ~ n f l g u r a t l o n , ~ and i n p a r t i c u l a r i t s p r o p u l - s l o n r a t l o o r r a t e and a c o u s t i c enhancement o f s i o n system. The c o n f i g u r a t i o n t o be discussed, m i x i n g might be used w i t h any o f these The has a d e l t a wing w i t h f o l d a b l e shown i n f i g u r e 2, present study deals w i t h o n l y t h e f i r s t t y p e e j e c t o r s through t h e wing adjacent t o t h e fuselage Based on d e t a i l e d analyses and experiments f o r t h t s t y p e o f e j e c t o r , t h e geometric charac- I n c o n s i d e r i n g t h e p r o p u l s i o n system f o r an t e r i s t i c s shown on t h e r l g h t o f f i g u r e 3 were advanced STOVL a l r c r a f t . t h e r e a r e several s e l e c t e d as g l v i n g good e j e c t o r performance o r a important c h a r a c t e r i s t l c s t o be considered which h i g h augmentatlon r a t i o : (a) a 1 8.1 e j e c t o r form t h e o u t l i n e f o r t h e paper e x i t t o t h r o a t area r a t i o , and (b) a d l f f u s e r w a l l h a l f angle o f 8 degrees This y i e l d s a
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*Deputy Chief, Advanced Programs and Planning secondary t o primary mass f l o w r a t i o , ms/mp. o f O f f i c e , Associate F e l l o w A I A A about 10 f o r equal primary and secondary f l o w **Aerospace Engineer d e n s i t i e s , and an augmentatlon r a t i o , cp o f eJ ' 'Head, Subsonic Mlssions Analysts Sectlon. about 1 7.
Even w i t h a high subsonic throat Mach num- ejector t h r u s t per u n i t fan p l u s ejector ducting ber, the thrust per volume of the ejector i s low frontal area, and (3) the t h r u s t per u n i t volume and the drag associated w i t h i t s volume I s of the propulsion system. Each of these w i l l be generally inconsistent w i t h supersonic f l i g h t discussed This problem i s overcome by assuming the ejector walls are foldable t o eliminate the diffuser Thrust Per Ejector Throat Area volume A key performance parameter of the ejector then becomes the thrust per throat area Figure 5 shows a typical ejector layout i n a For the case of the ejector i n the wing, a large d e l t a wing The purpose of t h i s ejector i s two value reduces the hole size t h a t must be cut f o l d . (1) t o augment the basic fan thrust (the through the wing fan flow i s the ejector primary flow) t o provide l i f t , and (2) t o provide an airplane nose.-up Aircraft Operation pitching moment about the a i r c r a f t center of gravity ( c . g ) f o r a i r c r a f t trim Because the purpose of the paper i s t o dls- cuss the propulsion system, i t i s important t o The ejector throat area t o wing area ratlo.
review how i t operates during a typical f l i g h t A t / & , i s related t o other a j r c r a f t and This i s i l l u s t r a t e d i n figure 4 engine characteristics by the relation STO Ground Run, sketch 1 ; For the short (At/Sw) = (&I%) (FtotlWG) take-off, e g , 400'. the core a i r i s directed (FfnlFtot) 'PO rearward, and the fan a i r i s burned i n the fan (l/Fej/At) a i r a f t duct and also directed rearward This, of course, i s t o achieve maximum axial accelera- The terms i n t h i s relation are defined below tion The a i r c r a f t i s a t near zero angle of and typical values a r e l i s t e d attack, and the ejector i s deployed ready f o r operati on Term: Typical Value- STO L i f t Off. sketch 2 . A t l i f t o f f the WG/& = a i r c r a f t wing 60 t o the fan a i r burner i s shut o f f , b u t a fuel loading. l b s / f t 2 small quantity of fan a i r may be s t i l l exhausted rearward t o keep the a f t duct clear of residual F t o t / W G = a i r c r a f t t h r u s t 0 8 fuel The main quantity of fan a i r I s directed loading forward, by a valve, t o the ejectors The ejec- t o r force must pitch the a i r c r a f t nose up t o F f n / F t o t = fan t o t o t a l thrust 0 31 18O t o ZOO angle of attack t o generate wing s p l i t l i f t i n addition t o the ejector l i f t The core nozzle i s deflected downward about 4 5 O t o 'po E Fej/Ffn = overall ejector 1 5 provide l i f t and thrust t o overcome the a i r c r a f t augmentation r a t i o and ejector drags This i s discussed i n more d e t a i l l a t e r Fej/At = ejector thrust t o throat 300 area r a t i o , lbs/ft2 Subsonic Crutse. sketch 3: For subsonic cruise, b o t h the fan f l o w and core flow are A t / & = ejector throat t o wing 07 directed rearward The fan a i r i s n o t a f t e r - area r a t i o burned and the engine i s a t part t h r o t t l e The ejector i s now folded i n contrast t o the case a t This relation shows that a high ejector takeoff t h r u s t per unit of ejector throat area, Fej/At, will reduce the area cut through the Supersonic Cruise and Combat, sketch 4: The wing structure A t / % , A reduced ejector fan and core j e t s a r e directed rearward, and the throat area w i l l also permit the moment arm t o fan a i r i s afterburned f o r supersonic cruise and the center of the ejector thrust, X c , t o combat increase, thus Increasing the ejector pifching moment capability Vertical Landing, sketch 5 ; The fan i s ducted t o the ejector whose j e t i s 90° t o the Figure 6 shows the results of a simple anal a i r c r a f t longitudinal axis, and the core a i r i s ysls of a steady f l o w ejector Figure 6a shows a l s o deflected down 90° A higher deflection that higher thrusts per u n i t throat area a r e may be needed during approach t o aid i n a i r c r a f t achieved by high, subsonic, secondary f l o w deceleration. The ejector ram drag i s helpful throat Mach numbers i n t h i s case Figure 6b relates the secondary flow throat Mach number t o the ejector primary pressure Basic Ejector Propulsion Parameters r a t i o and temperature Increasing the primary pressure r a t i o , especially up t o values of about W e begin w i t h a discussion of some basic 4 i s important, b u t increasing primary flow tem- ejector propulsion system parameters relevant t o perature i s also important The increase i n the baseline ejector a i r c r a f t and ejector a i r - secondary throat Mach number w i t h primary gas c r a f t In general before dlscussing some poten- temperature assumes the primary nozzle s i z e w i t h temperature, and that the t i a l growth system options Increases secondary flow geometry remains constant ( A Three propulsion system parameters of impor- l a t e r discussion considers the case of no p r i - tance t o a supersonic ejector a i r c r a f t a r e c ( 1 ) mary or secondary geometry change) The dotted the ejector thrust per u n i t throat area, ( 2 ) the l i n e , for example, shows a primary nozzle i pressure r a t i o o f 3, a p r i m a r y gas temperature F i g u r e 9b presents t h e corresponding e j e c t o r o f about 80O0R y i e l d i n g a secondary f l o w Mach tnput.
t h r u s t d i v l d e d by t h e f a n s h a f t energy number o f about 0 . 5 and a corresponding Fej/E. A h i g h v a l u e corresponds t o a reduced /A = 300 l b s / s q f t . I n t h e b a s e l i n e F f u e l consumption r a t e . Stnce t h e t a k e o f f and c:ie,t t h e e j e c t o r p r i m a r y pressure i s provided l a n d i n g times a r e short, t h e r e i s o n l y a s m a l l by t h e engine f a n . The source o f t h e h o t q u a n t i t y o f f u e l i n v o l v e d I n any case, f o r f a n primary temperature w t l l be discussed l a t e r pressure r a t i o s between 3 and 4. t h e r e i s n o t an i m p o r t a n t v a r i a t i o n tn Fej/E w i t h f a n pressure The p i t c h i n g moment an e j e c t o r o f a g i v e n r a t t o o r d u c t Mach number t h r o a t area w i l l produce depends on i t s l e n g t h t o w i d t h r a t i o , l/w. T y p i c a l r e s u l t s f o r T h r u s t Per P r o p u l s i o n Volume A t / % = 0.07 a r e shown i n f i g u r e 7 A n l / w o f about 3.5 y i e l d s t h e maxlmum p l t c h i n g moment The volume taken up i n t h e fuselage by t h e although t h e maximum i s f l a t A l a r g e r l/w, say p r o p u l s i o n system i s n o t a v a i l a b l e f o r payload 5, reduces t h e blockage t h a t t h e e j e c t o r d i s - o r f u e l , so a l o w volume p r o p u l s i o n arrangement charge causes t o t h e f r e e stream a i r f l o w i n g i s d e s i r a b l e F i g u r e 10 shows two p o s s i b l e a i r - under t h e wtng with l l t t l e r e d u c t i o n i n p i t c h i n g c r a f t arrangements For both, t h e englne i s moment from t h e optimum near t h e c e n t e r o f t h e a i r c r a f t and p r o v i s i o n s a r e made f o r t h e f a n a i r c o l l e c t l o n and d u c t l n g The sketch i n f i g u r e s 5 and 7 has an t o a forward e j e c t o r f o r t a k e o f f and l a n d i n g A t / % = 0 07 and an l / w = 5.0 I n t h e upper f i g u r e , I n t h e c r u i s e mode, t h e f a n a i r i s ducted t o , and exhausted a t t h e r e a r o f Thrust Per Fan Plus Duct F r o n t a l Area t h e a i r c r a f t Thts d u c t i n g occupies conslder- a b l e fuselage volume I n t h e lower f i g u r e , i n For an a i r c r a f t t o have supersonic c a p a b i l - t h e c r u i s e mode, t h e f a n a i r nozzle i s a d j a c e n t i t y , a low f r o n t a l area o f t h e a i r c r a f t , which t o t h e c o r e nozzle. A l t e r n a t i v e l y , t h e f a n and c o n s i s t s i n p a r t o f t h e p r o p u l s i o n system f r o n t a l c o r e a i r c o u l d be mixed and exhausted through a area, i s very i m p o r t a n t So an important p r o p u l common nozzle near t h e a i r f r a m e c e n t e r Thts s i o n system parameter i s t h e t h r u s t per propul reduces t h e p r o p u l s i o n system volume, b u t s i o n system f r o n t a l area For t h e e j e c t o r aggravates t h e fuselage angles i n t h e v i c i n i t y system, t h e f r o n t a l area shown I n f i g u r e 8 i s o f t h e nozzles A d e t a i l e d study i s needed t o made up o f t h a t p a r t o f t h e f a n f r o n t a l area r e s o l v e such questions t h a t provides t h e e j e c t o r a i r , Afn, p l u s t h e f r o n t a l o r cross s e c t i o n a l area o f t h e duct, Subsequent discussions w i l l deal w i t h these Ad, which I n t h e assumed a i r c r a f t , passes over geometric arrangements t o achieve o t h e r t h e f a n t o d e l f v e r t h e f a n a i r t o t h e e j e c t o r o b j e c t t v e s The cross s e c t i o n a l area o f t h e duct is determined by t h e mass f l o w i n t h e duct, and t h e E l e c t o r P r o w l s i o n Options duct f l o w Mach number, Md, which i n t u r n i s a f u n c t i o n o f t h e fan pressure r a t i o , FPR The Having presented t h e b a s e l i n e e j e c t o r a l r .
choice o f duct Mach number I s a l s o r e l a t e d t o c r a f t and some basic e j e c t o r p r o p u l s i o n para- t h e t o t a l pressure losses I n t h e d u c t which meters, t h e f o l l o w i n g discussion deals w i t h ways t h e p r o p u l s i o n system can be m o d i f i e d t o y i e l d g e n e r a l l y Increase w i t h t h e duct Mach number squared The duct losses a r e a l s o p r o p o r t i o n a l g r e a t e r t h r u s t performance, a cooler f o o t p r i n t , t o t h e number o f duct t u r n s , whlch i n t h l s case o r b e n e f i t from a l t e r n a t i v e propulston c y c l e and i s t h e primary source o f t h e losses The base- then categorizes these m o d i f i c a t i o n s from a line e j e c t o r system being considered has f o u r , c y c l e p o i n t o f view 90° turns, i l l u s t r a t e d I n f i g u r e 8: ( 1 ) from t h e a f t a x I a l d l r e c t i o n e x i t i n g t h e f a n t o Greater Performance upward, (2) from upward t o forward I n t h e d u c t passing over t h e fan, ( 3 ) from forward I n t h e E j e c t o r J e t D e f l e c t i o n . Conslder t h e possi fuselage duct t o outboard I n t o t h e wing where b i l i t y o f improving t h e a i r c r a f t performance a t t h e e j e c t o r i s , and ( 4 ) f r o m outward t o downward l i f t - o f f , f l g u r e 11 The base a l r c r a f t a t l i f t - as r e q u i r e d t o serve as t h e downward t h r u s t i n g o f f c o n d i t l o n s i s shown i n f i g u r e l l a The e j e c t o r primary e j e c t o r j e t , Fe i s normal t o a i r c r a f t l o n g i -
t u d i n a l a x i s , d' = 0, and t h e l i f t - o f f I s
The r e s u l t s o f an a n a l y s i s o f such a system assumed t o occur a t an a l r c r a f t angle o f attack, a r e shown i n f i g u r e 9 I n f i g u r e 9a, a = 200 The core j e t , F c r , 'IS a l s o Fej/(Afn + Ad) i s p l o t t e d versus f a n pres- d e f l e c t e d downward t o p r o v i d e b o t h l i f t and sure r a t i o f o r several values o f d u c t Mach t h r u s t , and t o balance t h e a i r c r a f t p i t c h i n g number A l a r g e value o f the o r d i n a t e i s d e s i r - moments V a r i a t i o n s from t h e b a s e l i n e a r e shown a b l e The curves show I n c r e a s i n g Fej/(Afn + i n t h e o t h e r two f i g u r e s F i g u r e l l b shows t h e e j e c t o r j e t d e f l e c t e d rearward so d = 40° Ad) w i t h i n c r e a s i n g f a n pressure r a t i o f o r a l l d u c t Mach numbers The e f f e c t o f t h e duct l o s s F i g u r e l l c shows t h e wing w i t h t r a i l i n g edge blowing so t h e d e s i r e d l l f t c o e f f i c i e n t can be may be seen f o r a Mg = 0 2 by comparing t h e dashed l i n e . whlch has no losses w i t h t h e s o l i d achieved a t Q = Oo l i n e whlch has t h e d u c t t u r n i n g losses i n c l u d e d The duct Mach number optimtzes between MO = 0 2 The forces on an example a i r p l a n e , { s e l e c t e d and 0 3 Higher d u c t Mach numbers reduce t h e t o i l l u s t r a t e t h e p o i n t o f t h e dlscusslon) i .e , duct cross s e c t i o n a l area, which I s favorable, l i f t , L; drag, D; and t h r u s t , F, as a f r a c t i o n b u t a l s o increase t h e losses which causes a o f t h e a i r p l a n e gross weight, W, a r e shown i n decrease t h e t h r u s t , which i s unfavorable The f i g u r e 1 2 as a f u n c t i o n o f t h e forward v e l o c i t y , t r a d e - o f f between these t w o e f f e c t s r e s u l t s I n V an optimum duct Mach number d I n f i g u r e 12a. l l f t - o f f can occur when L/W = by a temperature r a t i o o f e f Tb/Tno b and 1 . O A t t h e l i f t - o f f v e l o c i t y . about 110 fps. t h e pressure r a t i o remains constant, t h e e j e c t o r t h e wing, t h e e j e c t o r , and d e f l e c t e d c o r e j e t primary e x i t Mach number remains constant, b u t each p r o v i d e about 1/3 o f t h e l i f t Wing t h e e x i t v e l o c i t y ( v ) increases by 4 because supported f l i g h t can occur a t about 225 f p s t h e speed o f sound .Increases by & The f l o w d e n s i t y decreases by e so t h e mass f l o w r a t e The drag, f i g u r e 12b, i s made up o f t h e per u n i t area (m), which i s t h e product o f a i r f r a m e drag, p l u s t h e engine c o r e a i r ram v e l o c i t y and d e n s i t y . decreases by 6. The drag, p l u s t h e e j e c t o r ram drag The a v a i l a b l e primary t h r u s t , mv, i s then independent o f e t h r u s t i s made up o f t h e core t h r u s t from t h e and so i s t h e e j e c t o r t h r u s t i f t h e augmentation d e f l e c t e d core j e t and t h e reverse t h r u s t o f t h e r a t i o remains constant I n summary, i n c r e a s i n g e j e c t o r , reverse because i t i s blowing forward t h e primary a i r temperature a t constant t o t a l a t an angle corresponding t o t h e a i r c r a f t angle pressure does n o t a f f e c t t h e primary o r e j e c t o r o f a t t a c k , a = 20° A minimum l e v e l o f T/W t h r u s t s , b u t reduces t h e primary mass f l o w r a t e above O/W, o f about 0 06, i s r e q u i r e d f o r
by %
a i r c r a f t a x i a l a c c e l e r a t i o n With no e j e c t o r d e f l e c t i o n , d = 0, and f o r t h e selected Now, i f t h e e j e c t o r primary a i r temperature a i r c r a f t t h r u s t t o weight r a t i o , t h e margin o f e = i s increased, f o r example, by a f a c t o r t h r u s t over drag i s unacceptable a t l i f t - o f f , 4, as by a burner as shown i n f i g u r e 13b,Prthe L/W = 1 0 primary mass f l o w from t h e fan t o the e j e c t o r i s reduced t o h a l f The other h a l f o f t h e mass An obvious way t o improve t h i s s i t u a t i o n i s i s assumed t o discharge through f l o w from the f a n t o d e f l e c t t h e e j e c t o r j e t rearward, say by d t h e a f t fan a i r duct, a l s o shown i n f i g u r e 13b.
= 400, which then y i e l d s a forward t h r u s t o f 2, and can be augmented by burning by a r a t i o component equal t o t h a t which was t h e reverse
corresponding t o gad - 4 0 The numerical
t h r u s t component and t h e same l i f t The margin values on t h e f i g u r e a r e based on t h e sum o f t h e o f a i r c r a f t t h r u s t over drag a t l i f t - o f f i s now fan and core t h r u s t s being 100% and an example s i g n i f i c a n t l y improved, i t i s about 0 2 g ' s , a engine w i t h a f a n t o core t h r u s t s p l i t o f much more d e s i r a b l e l e v e l Ffn/Fcr = 0 45 The values i n t h e boxes i n d i c a t e t h e p o s s i b l e percent t h r u s t augmenta The above d i s c u s s i o n r a i s e s several t i o n The example i n f i g u r e 13b shows a 31 questions: percent t h r u s t augmentation 1 Is t h e e f f e c t i v e e j e c t o r j e t angle set An a l t e r n a t i v e way o f h e a t i n g the e j e c t o r o n l y by the geometry o f t h e e j e c t o r o r i s i t primary a i r i s by m i x i n g i t w i t h t h e core flow, s i g n i f i c a n t l y e f f e c t e d by t h e e x t e r n a l f l o w as i l l u s t r a t e d i n f i g u r e 13c f i e l d a t l i f t - o f f ? This needs t o be determined experimentally I n t h e l i m i t , f o r t h e same fan t o core t h r u s t s p l i t used above, a l l t h e e j e c t o r primary a i r 2 Can an e j e c t o r be designed w i t h a could be core flow, f i g u r e 13d The fan f l o w v a r i a b l e d e f l e c t i o n c a p a b i l i t y w i t h l i t t l e l o s s e x i t i n g the fan a i r nozzle can be burned, i n e j e c t o r augmentation r a t i o ? This a l s o y i e l d i n g a t h r u s t augmentation o f 31 percent r e q u i r e s experimental study One o f t h e advantages o f using t h e core a i r Another approach i l l u s t r a t e d i n f i g u r e l l c f o r t h e e j e c t o r and i n t h e a f t duct, as i n f i g u r e i s t o generate t h e wing l i f t a t near zero angle 13d, can be understood by considering t h e take.
o f a t t a c k by wing t r a i l i n g edge blowing and thus o f f sequence o f events F o r a c c e l e r a t i o n down e l i m i n a t e the e j e c t o r reverse t h r u s t e f f e c t t h e runway, t h e h o t core a i r I s d i r e c t e d r e a r - However, t h e r e would s t i l l be an a i r c r a f t accel ward i n the a f t d u c t The fan a i r i s d i r e c t e d e r a t i o n advantage t o some a f t d e f l e c t i o n , e g , rearward by t h e lower v a r i a b l e d e f l e c t i o n noz- d = 20°, o f t h e e j e c t o r j e t z l e The fan a i r can be burned The b u r n i n g i s i n i t i a t e d a t t h e s t a r t o f t h e ground r u n and E j e c t o r Primary A i r Heating Plus A f t Fan A i r continues through l i f t - o f f and t r a n s i t i o n t o Burning. Another way t o improve t h e l i f t o f f wingborne f l i g h t A t l i f t - o f f , most o f t h e core performance i s t o heat t h e primary a i r f o r t h e f l o w i s d i r e c t e d t o t h e e j e c t o r , and t h e burned e j e c t o r , see f i g u r e 13 f a n f l o w i s d e f l e c t e d downward by t h e lower v a r l a b l e d e f l e c t l o n nozzle Thls system avoids The b a s e l i n e e j e c t o r system uses unheated t h e burner l i g h t r e q u i r e d a t l i f t - o f f by t h e f a n a i r when t h e e j e c t o r i s used, f i g u r e 13a. systems i n d i c a t e d by f i g u r e 13b, f o r t h e b u r n i n g b u t an a f t duct burner i s used a t o t h e r times as o f t h e fan e j e c t o r primary a i r , and i n f i g u r e described e a r l i e r I n t h e d i s c u s s i o n o f f i g u r e 4 13c f o r t h e b u r n i n g o f t h e f a n a i r e x i t i n g t h e v a r i a b l e d e f l e c t i o n core nozzle Before proceeding w i t h d i s c u s s i n g t h i s o p t i o n , i t i s i n t e r e s t i n g t o note t h a t i n p r i n - I n comparing t h e options f o r h e a t i n g t h e c i p a l , primary a i r h e a t i n g can be done w i t h no e j e c t o r primary a i r , f a n a i r burning, f i g u r e change i n e j e c t o r geometry, e i t h e r primary noz. 13b, o r use o f t h e h o t core flow, f i g u r e 13d.
z l e s o r secondary f l o w geometry This assumes f o r t h e present example, they both g i v e t h e same t h a t t h e primary nozzle pressure r a t i o remains t h r u s t augmentation, b u t t h e use o f t h e core a i r constant (1 e , n e g l i g i b l e t o t a l pressure l o s s appears simpler from an engine p o i n t o f view b u t due t o combustion), t h a t i t i s s u f f i c i e n t t o n o t n e c e s s a r i l y from an a i r c r a f t i n t e g r a t i o n choke t h e primary nozzle t h r o a t ( g e n e r a l l y t h e p o i n t o f view case), and t h e e j e c t o r augmentation r a t i o rematns constant (i e , t h e primary and secondary m i x i n g F i g u r e 14 presents t h e t h r u s t augmentation a r e adequate) When t h e prtmary j e t i s heated f o r t h e e j e c t o r primary a t r burntng o p t i o n of f i g u r e 13b i n a more general way It presents temperatures t h a t a r e now forward a r e more t h e e j e c t o r p r i m a r y a i r t h r u s t augmentation l i k e l y t o be i n g e s t e d by t h e englne i n l e t r a t i o as a f u n c t i o n o f t h e b u r n i n g temperature r i s e The example c o n d i t i o n f o r f i g u r e 13b i s Second E l e c t o r f o r t h e Enslne Core Flow: A i n d i c a t e d by t h e c i r c l e symbol An i m p o r t a n t d i r e c t approach t o c o o l i n g t h e core f l o w i s t o p o i n t from t h i s f i g u r e i s t h a t t h e t h r u s t aug- add a second e j e c t o r around t h e core flow, f i g u r e mentation v a r i e s l i k e t h e square r o o t o f t h e 16d I t s primary purpose i s t o c o o l t h e j e t and temperature r i s e , t h a t i s , t h e i n i t i a l increment s e c o n d a r i l y t o augment i t s t h r u s t Such an o f h e a t a d d i t l o n g i v e s t h e l a r g e r t h r u s t e j e c t o r was dlscussed i n reference 6 It may augmentation reduce t h e core temperature from l50O0F t o 900°F, f o r example.
The e f f e c t on t a k e o f f performance o f b u r n i n g = 4 i n a p r o p u l s i o n t h e primary a i r t o epr The XFV-12A System: I n t h i s system7 t h e system l i k e 13b. i n an a i r c r a f t l i k e t h a t o f f a n and c o r e a i r a r e f i r s t mixed, thus c o o l i n g A t t h e ZOO f i g u r e l l a , i s shown i n f i g u r e 15 t h e c o r e f l o w and then t h e e n t i r e engine f l o w l i f t - o f f a n g l e o f a t t a c k , t h e j e t o u t t h e r e a r becomes t h e primary f l o w f o r e j e c t o r s so t h e o f t h e a i r c r a f t , which does n o t e x i s t i n t h e primary temperature I s f u r t h e r reduced by t h e b a s e l i n e case a t l i f t - o f f , p r o v i d e s some l i f t e j e c t o r secondary f l o w .
which reduces t h e l i f t - o f f speed as shown i n f l g u r e 15a T h i s r e s u l t s i n a lower drag a t F i g u r e 17 shows how t h e e j e c t o r and mixed l i f t - o f f , f i g u r e 15b The a f t j e t a l s o provides core exhaust f l o w temperatures vary w i t h t h e l a r g e amount o f t h r u s t so t h a t t h e t h r u s t over e j e c t o r primary a i r b u r n l n g temperature r i s e f o r d r a g margin i s s i g n i f i c a n t l y improved over t h e t h e engine arrangement o f f i g u r e 16b As w i t h b a s e l i n e case, f i g u r e 15b. t h e t h r u s t augmentation, t h e I n i t i a l increments I n primary a-lr b u r n i n g r e s u l t i n t h e l a r g e r I n summary, two techniques f o r improving mixed core f l o w temperature reductions l i f t - o f f performance have been discussed- (1) e j e c t o r j e t a f t d e f l e c t i o n a t l i f t - o f f , and (2) I n summary, t h e b a s e l i n e e j e c t o r system has h e a t i n g o f t h e e j e c t o r prlmary a l r by b u r n i n g o r t h e advantage o f a c o o l f r o n t f o o t p r i n t Two o f by u s i n g engine core f l o w Both o f f e r s i g n i f i - t h e schemes discussed r e s u l t i n s l i g h t l y h i g h e r c a n t l i f t - o f f t h r u s t enhancement, b u t a t t h e f r o n t f o o t p r i n t temperature t o reduce t h e a f t expense o f increased complexity, and probably f o o t p r i n t Adding a second e j e c t o r on t h e c o r e weight it, maintains t h e c o o l b a s e l i n e j e t f o r c o o l i n g f r o n t f o o t p r i n t temperature The XFV-1ZA system Next, we w i l l consider c o o l i n g t h e f o o t p r i n t o f m i x i n g t h e f a n and core flows and u s i n g a l l t h i s f l o w as t h e primary f l o w f o r e j e c t o r s p r o - Cooler F o o t p r i n t bably r e s u l t s i n t h e lowest average temperature One o f t h e advantages o f t h e b a s e l i n e e j e c - Propulsion Cycles t o r system over some o f t h e o t h e r STOVL concepts i s t h e cool, low v e l o c i t y , f r o n t f o o t p r i n t There appears t o be t h r e e categories o f generated by t h e e j e c t o r The s u b j e c t of t h i s p r o p u l s i o n cycles, shown i n f i g u r e 18, o f primary d i s c u s s i o n and f i g u r e 16 a r e some o f t h e p o s s i . A l l i n t e r e s t f o r e j e c t o r p r o p u l s i o n systems b i l i t i e s f o r reducing t h e temperature o f t h e a f t t h e engines discussed thus f a r a r e two-spool o f the b a s e l i n e a i r c r a f t , o r core f o o t p r i n t t u r b o f a n englnes, f i g u r e s 18a, b, and c F i g u r e f i g u r e 16a 18d i s t h e newest and most unique o f t h e engine c y c l e s E j e c t o r Primary A i r Burnins and Fan and Core A i r Mlxing: I n t h e preceding s e c t i o n i t was Separate Fan and Core Flow: I n t h e b a s e l i n e p o i n t e d o u t t h a t i f t h e f a n a i r going t o t h e system, f i g u r e 18a, t h e f a n and core flows a r e i s heated by a temperature r a t i o e j e c t o r primary always separate Thls gives t h e g r e a t e s t freedom o f 4, then h a l f o f t h e f a n a i r i s a v a i l a b l e f o r t o o p t i m i z e t h e choice o f f a n pressure r a t l o and It may a l s o r e q u i r e t h e o t h e r purposes For t h e present purpose, t h e engine bypass r a t i o c o o l e r primary a i r can be mixed w t t h t h e c o r e g r e a t e s t p r o p u l s l o n system volume i n t h e a i r - f l o w , f i g u r e 16b, t o reduce t h e j e t temperature c r a f t i f l t r e q u i r e s t h e f a n a i r a f t duct, shown from 150OoF t o llOO°F Thls method y i e l d s i n f i g u r e 10a improved l i f t - o f f performance, b u t a l s o a small increase i n t h e e j e c t o r j e t temperatures f o r t h e An a l t e r n a t e arrangement t h a t maintains i s t o d u c t a l l t h e r e d u c t i o n i n c o r e j e t temperature separate f a n and c o r e f l o w c o r e f l o w t o t h e e j e c t o r o r o u t t h e a f t duct, E j e c t o r Primary From Core J e t : Another f i g u r e 18b The engine c y c l e must be selected approach which was discussed i n t h e preceeding t o y i e l d d e s i r a b l e e j e c t o r primary f l o w charac- section, f i g u r e 13d. which can a l s o be used t o t e r i s t i c s The f a n a i r i s always exhausted reduce t h e j e t temperatures, i s t o use t h e engine through a v a r i a b l e d e f l e c t l o n nozzle on t h e core j e t f o r t h e e j e c t o r primary flow; and t h e underside o f t h e a i r c r a f t , so t h e f a n and c o r e c o o l , unburned f a n f l o w f o r t h e a f t j e t , f l g u r e f l o w s always remain separate 16c The a f t j e t i s now q u i t e cool, 28OoF, and t h e e j e c t o r j e t average temperature i s S e p a r a t e K o n f l u e n t Fan and Core Flow: I n 1400F. compared w i t h 1500°F f o r t h e o r l g i n a l t h l s scheme, f i g u r e 18c, t h e f a n and core f l o w s core flow, f l g u r e 16a This gives one o f t h e a r e separate d u r i n g e j e c t o r operation, b u t a r e c o o l e s t arrangements confluent d u r i n g t h e t a k e o f f ground r o l l , and d u r i n g up-and-away o p e r a t l o n This system The dlsadvantages o f t h i s arrangement a r e reduces t h e c o r e exhaust temperature when t h e t h e h o t core f l o w d u c t l n g , and t h a t t h e warmer two stream a r e mixed, and reduces t h e p r o p u l s l o n system volume on t h e a i r c r a f t i Its cycle optimization may be restricted by 2 Sheridan. A E , "The Applicatlon of Turbine the requirement for core and fan static pressure Bypass Engines t o High Performance V/STOVL matching during confluent operatlon. and t h e Aircraft," AIAA Paper 83-2512, Oct 1 9 8 3 problem of low body surface angles for low super- sonic drag may be aggravated 3 Franciscus. L C , 'Supersonic STOVL Air- craft With Turblne Bypass/Mass Flow Ampll- Another option is to keep t h e core and fan fier Englnes," AIAA-84.1403, June 1984 flows separate even though exhausting adjacently 4 Zola, C L , Wilson. S L , 111. and Eskie, The above systems all require two spool M A , "Tandem Fan Applications in Advanced turbofan engines The following system is sin- STOVL Fighter Configurations.' AIAA- 84-1402, June 1984 gle spool Turbine Bypass Engine and TurbocomDressor 5 Foley, W H , Sheridan, A E , and Smith. C Stage; The turbine bypass engine, references 2 H., "Study of Aerodynamlc Technology for and 3 . figure 18d. is a single spool engine like Slngle-Cruise-Engine V/STOVL Fighter/Attack a turbojei, but i s characterized, typically. by Aircraft." NASA CR 166268, Feb. 1982 1 5 percent compressor bleed at a compressor pressure ratlo of about 16 at full throttle at 6, Wlllis. W . S . , Konarski, M , and Sutherland.
takeoff or landing condition This bleed air W. V , "Conceptual Design, Evaluation and can be used to drive a turbocompressor unit, TC, Research Identification for Remote Augmented figure 18d. which produces flow at a pressure Propulsive Lift Systems (RALS) With Ejectors ratio of 3 5 to 4 0 which in turn may be used as For VTOL Aircraft." General Electric Co , the primary air for the ejector When not used Cincinnati, OH, R82AEB315, May 1982 (NASA for the ejector, the TC jet can be used for CR- 167906) acceleration during the ground roll and for combat maneuvers This is a relatively new 1 Braden, R P , Nagaraja, K S , and Von concept and needs further evaluation Ohain. H J P , "Proceedings. Ejector Workshop for Aerospace Applications," AFWAL-TR-82-3059, June 1982 Concludinq Remarks The Initial discussion shows the baseline ejector aircraft prefers high pressure ratio fans, FPR = 3 5 to 4 0, and can benefit from an increase In primary air temperature Beyond this, there are a number of options for growth or advancement in aircraft characteristics over those o f the baseline, but usually at the expense of jncreased complexity and possibly increased weight Improved aircraft llft-off performance can be obtained by: ( 1 ) adjustable ejector jet aft deflection and (2) ejector prlmary air heating by burning or the use of the hot core flow Cooler aft, or core, footprints can be approached in a number of ways, for example, (1) by mixing or djsplacing the hotter core flow with the cooler fan flow, or (2) by a core air cooling ejector The single spool turbine bypass engine with turbocompressor unit which provides air at the desired pressure for the ejector primary and thrust for combat maneuvers is an alternative to the twin spool fan engine Finally, the baseline delta wing -ejector configuratlon is a valuable, relatively simple.
startlng point for many possibilities for enhanced performance, cooler footprints. and advanced engine cycles References 1 Kidwell. G H , Jr and Lampkln, B A , "An Evaluation of Supersonic STOVL Technology," AIAA Paper 83-2493, Oct 1983 i
t t
REMOTE AUGMENTED LIFT SYSTEM m-mu TANDEM FAN SYSTEM
Figure 1 . - Supersonic STOVL propulsion. C-82-1659
EJECTOR SYSTEM CD-82-12WB DEFLECTED THRUST SYSTEM
Figure 2. - Supersonic STOVL propulsion. C-82-1658
J MODEST PRIMARY PRESSURE RATIO , U S E D FOR THIS STUDY WITH (SUBSONIC SECONDARY FLOW) FOLLOWING ASSUMPTIONS : STEADY PRIMARY REFERENCE EJECTOR ROTATING PRIMARY "PRIMARY" NOZZLE PULSED PRIMARY HIGH PRIMARY PRESSURE RATIO SUPERSONIC SECONDARY TWO STAGE BLOWN OR UNBLOWN DIFFUSERS ACOUSTICALLY ENHANCED MIXING Figure 3. - Ejector types.
Figure 4 . - Ejector propulsion modes for supersonic STOVL.
A - EJECTOR THROAT KEY PARAMETERS EJECTOR HOLE SIZE IN WING
&ISw ,., l/CFej/&)
C EIECTOR PITCHING MOMENT Figure 5 . - Ejector and wing geometries.
% -
r
e -
> - 500
L a
s400
CY
a
I- 300
a CY I- 2 .
I-
2 100
Ly: PRIMARY I GAS TEMPERATURE, I O R I
0 .1 .2 . 3 . 4 .5 .6 .7 . 8
SECONDARY FLOW THROAT MACH NUMBER, Mt Figure 6. - Ejector thrust per thoat area.
Sea level static conditions.
1.50 1.25
I-- -- b -+
1.00 0 1 2 3 4 5 6 7 8
EJECTOR ASPECT RATIO, a Iw
Figure 7. - Ejector pitching moments.
I i A f n , FPR Figure 8 - Ejector propulsion system parameters.
2 50
2 2 5
Z O O
1 . 7 5
1 . 5 0
1 . 2 5
LOO
-75
.50
.25
4 5
4 . 0
3 . 5
17- LOSSES DUE TO DUCTING
3 . 0
2 . 5
2.0
1 . 5
1 . 0
1 2 3 4 5
FAN PRESSURE RATIO
Figure 9 . - Ejector t h r u s t per frontal
area and fan power i n p u t
,.' " " 7 I
r ' I 0 " I I (a) Fan a i r exhausted at rear of aircraft.
(b) Fan a i r exhausted adjacent to core nozzle.
Figure 1 0 . - Effect of fan a i r ducting on available fuselage
volume.
Mla ONb' 'MlJ 'Ml'W 'lH31lM 01 3Vda
M / l 'OIlVtl lH313M 01 Uil - - m aNV 'ISfldHl 'WnlNlbOW 11x3 4 0 SOllVtl Z
a , vi
.-
x m 0' I1 Lo
--
-
m AFT DUCT BURNER 7,
m
AF
Ffn + Fcr (a) Baseline, cool fan flow to ejector.
EJECTOR PRIMARY r AFT DUCT BURNER AIR BURNER, (b) Burned fan flow to ejector.
(c) Mixed cool fan flow and hot core flow to ejector.
AFT D U C T 7 \ (d) All core flow to ejector.
Figure 13. - Ejector primary a i r heating options
a t lift-off conditions.
O 1 0 0 h \ O m d O O 1 m h \ O m d m N A 0 . . . . . . . . . . .
* A s - - M/a aNV M/d
’1H313M 01 3tllla (INV ‘lSIIl!HlJO SOlltlll MI1 ’OllVll lH313M 01 Ull Z
L
.-
m AFT DUCT BURNER-, I
(a) Baseline, cool fan flow to
ejector.
E
T =
T = iiooo F
(b) Mixed cool fan and core flows.
AFT DUCT?
\
T = 2 8 0 ' F
(c) All core flow to ejector
AFT DUCT BURNER 7 I
T = 9 0 O 0 F
(d) Core flow cooling ejector.
Figure 16. - Exhaust jet cooling options
at lift-off conditions.
L
t
1 1
r-
I - o n
t
a I 0 0 Ln
x
8 h 8 m 8
Ln 4 b-4 b-4 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No.
NASA TM-83641
5. Report Date
Supersonic STOVL Ejector Aircraft from a
Propulsion Point of View
6. Performing Organization Code
505- 40- 82
7 Author@) 8. Performing Organization Report No.
R. Luidens, R. Plencner, W. Haller, and A. Glassman E- 2084
IO. Work Unit No.
9. Performing Organization Name and Address 11. Contract or Grant No.
National Aeronautics and Space Administration
Lewis Research Center
1 3 . Type of Report and Period Covered
Cleveland, Ohio 44135
2. Sponsoring Agency Name and Address
Technical Memorandum
National Aeronautics and Space Administration
14. Sponsoring Agency Code
Was h i ngton , D . C. 20546
5. Supplementary Notes
Prepared f o r the Twentieth Joint Propulsion Conference cosponsored by the
AIAA, SAE, and ASME, Cincinnati, Ohio, June 11-13, 1984.
6. Abstract
The paper first describes a baseline supersonic STOVL ejector a i r c r a f t , including
i t s propulsion and typical operating modes, and identifies important propulsion
parameters. T h e n a number of propulsion system changes are evaluated i n terms
o f i m p r o v i n g the lift-off performance; namely, a f t deflection of the ejector j e t and heating o f the ejector primary a i r e i t h e r by b u r n i n g o r u s i n g the hot engine
The possibility for cooling the footprint i s i l l u s t r a t e d f o r the
core flow.
cases of m i x i n g or interchanging the fan and core flows, and u s i n g a core flow
ejector. Finally, the application of a new engine concept is presented, the
turbine bypass engine plus a turbocompressor t o supply the ejector primary a i r , and thrust d u r i n g take-off combat.
7 Key Words (Suggested by Author@)) 18. DlstrlbutionStatement
STOVL Uncl assi f i ed - u n l imi ted
Ejector STAR Category 07
@. SOCUdtY ClMSlf. (Of thl8 fopoft) #). WUdty ClMSff. (Of this me) 21. No. of pages 22. Price.