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Effect of Spatial Inlet Temperature and Pressure Distortion on Turbofan Engine Stability ·...

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NASA Technical Memorandum 100850 AIAA-88-3016 I t Effect of Spatial Inlet Temperature and Pressure Distortion on Turbofan Engine Stability {NASA-TN-100850) EFFECT OF SPATIAL IB'LET N88-21162 TEHPERBTURE AND PRESSURE DISTORTION OH TURBOFAN ENGINE STBBXLITY (NASA) 19 p CSCL 21E Unclas 63/07 0140260 Charles M. Mehalic Lewis Research Center Cleveland, Ohio Prepared for the 24th Joint Propulsion Conference cosponsored by the AIM, ASEE, ASME, and SAE Boston, Massachusetts, July 1 1 - 13, 1988 .I) https://ntrs.nasa.gov/search.jsp?R=19880011778 2020-03-31T18:00:12+00:00Z
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  • NASA Technical Memorandum 100850 AIAA-88-3016

    I

    t Effect of Spatial Inlet Temperature and Pressure Distortion on Turbofan Engine Stability

    {NASA-TN-100850) EFFECT OF SPATIAL I B ' L E T N88-21162 TEHPERBTURE A N D PRESSURE DISTORTION O H TURBOFAN E N G I N E S T B B X L I T Y (NASA) 19 p

    CSCL 21E Unclas 63/07 0140260

    Charles M. Mehalic Lewis Research Center Cleveland, Ohio

    Prepared for the 24th Joint Propulsion Conference cosponsored by the AIM, ASEE, ASME, and SAE Boston, Massachusetts, July 1 1 - 13, 1988 . I )

    https://ntrs.nasa.gov/search.jsp?R=19880011778 2020-03-31T18:00:12+00:00Z

  • EFFECT OF SPATIAL INLET TEMPERATURE AND PRESSURE DISTORTION ON TURBOFAN ENGINE STABILITY

    C h a r l e s M . M e h a l i c * 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

    Lew is R e s e a r c h C e n t e r C l e v e l a n d , O h i o 44135

    A b s t r a c t

    An e x p e r i m e n t a l i n v e s t i g a t i o n was c o n d u c t e d i n an a l t i t u d e f a c i l i t y t o d e t e r m i n e t h e e f f e c t s o f s t e a d y - s t a t e i n l e t t e m p e r a t u r e d i s t o r t i o n , p r e s s u r e d i s t o r t i o n , and c o m b i n e d t e m p e r a t u r e and p r e s s u r e d i s t o r t i o n o n t h e s t a b i l i t y o f a PW1128 t u r b o f a n e n g i n e . The s t e a d y - s t a t e t e m p e r a t u r e

    2 d i s t o r t i o n was g e n e r a t e d b y a g a s e o u s - f u e l e d h y d r o g e n b u r n e r . P r e s s u r e d i s t o r t i o n was p r o -

    & d u c e d b y a s c r e e n i n s t a l l e d i n t h e i n l e t d u c t i n g b e t w e e n t h e b u r n e r and t h e e n g i n e i n l e t . N i t h t h e e x c e p t i o n s o f i n l e t p r e s s u r e d i s t o r t i o n , a t i p - r a d i a l i n l e t t e m p e r a t u r e d i s t o r t i o n a t t h e h i g h e s t c o r r e c t e d f a n speed t e s t e d , and combined d i s t o r - t i o n w i t h t h e l o w - p r e s s u r e and h i g h - t e m p e r a t u r e r e g i o n s t o g e t h e r , t h e f a n g e n e r a t e d a f l o w i n s t a - b i l i t y when o p e r a t i n g n e a r i t s s t e a d y - s t a t e s t a l l l i n e . I n some i n s t a n c e s t h e f a n '.vas n o t t h e f i r s t component t o s u r g e , h o w e v e r , because t h e i n s t a b i l - i t y d i s r u p t e d t h e f low t o t h e h i g h - p r e s s u r e com- p r e s s o r c a u s i n g i t to s u r g e a t , o r n e a r , t h e same t i m e as t h e f a n . The e f f e c t o f combined d i s t o r - t i o n was d e p e n d e n t o n t h e r e l a t i v e l o c a t i o n s o f t h e h i g h - t e m p e r a t u r e and l o w - p r e s s u r e r e g i o n s ; h i g h - p r e s s u r e c o m p r e s s o r s t a l l o c c u r r e d when t h e d i s t o r t e d r e g i o n s were t o g e t h e r , and f a n s t a l l o c c u r r e d when t h e d i s t o r t e d r e g i o n s were d i a m e t r i - c a l l y o p p o s e d .

    I n t r o d u c t i o n

    A c o n t i n u i n g p r o b l e m e n c o u n t e r e d i n t h e d e s i g n and d e v e l o p m e n t o f a d v a n c e d a i r b r e a t h i n g p r o p u l s i o n s y s t e m s for m i l i t a r y a i r c r a f t i s t h e d e t r i m e n t a l e f f e c t o f n o n u n i f o r m i n l e t f l o w on c o m p r e s s i o n s y s t e m p e r f o r m a n c e and o n s t a b i l i t y l i m i t s . I n l e t t e m p e r a t u r e d i s t o r t i o n , b o t h spa- t i a l a n d / o r t i m e v a r i a n t , a l o n e or combined w i t h i n l e t p r e s s u r e d i s t o r t i o n . d e g r a d e s e n g i n e p e r - f o r m a n c e and can r e s u l t i n t o t a l power l o s s by c a u s i n g c o m p r e s s i o n s y s t e m components ( f a n o r com- p r e s s o r ) t o s t a l l . I n l e t t e m p e r a t u r e d i s t o r t i o n i s o f p a r t i c u l a r c o n c e r n i n a p p l i c a t i o n s r e l a t i n g t o i n g e s t i o n o f h o t gases from armament f i r i n g o r c a t a p u l t l a u n c h s y s t e m s , f r o m r e c i r c u l a t i o n o f er ,g ine e x h a u s t g a s e s f r o m t h r u s t v e c t o r i n g / r e v e r s i n g s y s t e m s , or f r o m o p e r a t i o n o f h e l i c o p t - e r s and V/STOL a i r c r a f t . I n t h e p a s t , s y s t e m o p e r - a b i l i t y p r o b l e m s c a u s e d b y i n l e t t e m p e r a t u r e d i s t o r t i o n have been s o l v e d b y a v o i d i n g o r m i n i - m i z i n g t h e e f f e c t o f t h e d i s t o r t i o n t h r o u g h s y s t e m c o n f i g u r a t i o n a n d / o r o p e r a t i n g p r o c e d u r e c h a n g e s . T h i s a p p r o a c h may n o t be a d e q u a t e for p r o p u l s i o n s y s t e m s o f t h e f u t u r e , and a b e t t e r u n d e r s t a n d i n g o f t u r b i n e e n g i n e r e s p o n s e t o i n l e t t e m p e r a t u r e d i s t o r t i o n w i l l be r e q u i r e d .

    An e x t e n s i v e e x p e r i m e n t a l effort has been c a r r i e d o u t a t t h e L e w i s R e s e a r c h C e n t e r t o e s t a b - l i s h a d a t a b a s e for e v a l u a t i n g t h e e f f e c t s o f i n l e t f low d i s t o r t i o n on t h e p e r f o r m a n c e o f t u r - b i n e e n g i n e c o m p r e s s i o n s y s t e m s . T h i s work

    i n c l u d e s i n v e s t i g a t i o n s u s i n g t ~ r b o j e t l - ~ , t u r b o -

    s p a t i a l ( s t e a d y - s t a t e ) a n d t i m e - v a r i a n t i n l e t p r e s s u r e d i s t o r t i o n , i n l e t t e m p e r a t u r e d i s t o r t i o n , and c o m b i n a t i o n s o f p r e s s u r e and t e m p e r a t u r e d i s - t o r t i o n . As a r e s u l t of t h e s e i n v e s t i g a t i o n s , d e v i c e s t o g e n e r a t e t h e s p a t i a l and t i m e - v a r i a n t i n l e t tem e r a t u r e a n d p r e s s u r e d i s t o r t i o n s were d e v e l o p e d y 8 - 2 0 .

    t i n u a t i o n o f t h e e f f o r t t o e s t a b l i s h an i n l e t flow d i s t o r t i o n d a t a b a s e a n d t o d e v e l o p a b e t t e r u n d e r s t a n d i n g of t h e e f f e c t s o f d i s t o r t i o n o n t u r - b i n e e n g i n e p e r f o r m a n c e . T h i s r e p o r t i s c o n c e r n e d w i t h t h e e f f e c t o f s p a t i a l i n l e t t e m p e r a t u r e d i s - t o r t i o n and combined i n l e t t e m p e r a t u r e and p r e s - s u r e d i s t o r t i o n o n t h e s t a b i l i t y l i m i t s of a P r a t t & W h i t n e y A i r c r a f t PW1128 t u r b o f a n e n g i n e . A g a s e o u s - f u e l e d h y d r o g e n b u r n e r l o c a t e d u p s t r e a m o f t h e e n g i n e i n l e t was used t o g e n e r a t e t h e t e m - p e r a t u r e d i s t o r t i o n s , and a s c r e e n was used t o p r o d u c e i n l e t p r e s s u r e d i s t o r t i o n .

    T h i s i n v e s t i g a t i o n was c o n d u c t e d w i t h 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 d i s t o r t i o n s o f 90"- and 1 8 0 " - e x t e n t . H u b - r a d i a l and t i p - r a d i a l t e m p e r a - t u r e d i s t o r t i o n p a t t e r n s were a l s o i n v e s t i g a t e d . A 1 8 0 " - e x t e n t t o t a l - p r e s s u r e d i s t o r t i o n , a l o n e and i n c o m b i n a t i o n w i t h a 1 8 0 " - e x t e n t t e m p e r a t u r e d i s t o r t i o n , was a l s o t e s t e d . A l l t e s t s were con- d u c t e d i n an a l t i t u d e f a c i l i t y a t an e n g i n e i n l e t R e y n o l d s number i n d e x o f 0 . 5 2 .

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    The t e s t p r o g r a m was c o n d u c t e d i n one of t h e two a l t i t u d e chambers of t h e P r o p u l s i o n Sys tems L a b o r a t o r y a t t h e L e w i s R e s e a r c h C e n t e r . These t e s t c e l l s a r e 24 f t i n d i a m e t e r , 3 9 f t l o n g , and have t h e c a p a b i 1 i t y o f s i m u l a t i n g a i t i t u d e s f r o m n e a r sea l e v e l t o 80 000 f t , w i t h maximum a i r f l o w r a t e s o f 480 and 50 l b l s e c , r e s p e c t i v e l y . C o n d i - t i o n i n g e q u i p m e n t i s a v a i l a b l e t o s u p p l y a i r tem- p e r a t u r e s r a n g i n g from -50 t o 600 " F .

    t e s t c e l l i s shown i n F i g . 1 . A d i r e c t - c o n n e c t i n s t a l l a t i o n was u s e d , w i t h an i n l e t a i r b e l l m o u t h moun ted i n t h e p l e n u m u p s t r e a m o f t h e t e s t c e l l f o r w a r d b u l k h e a d . The e n g i n e was moun ted o n a t w o - d i m e n s i o n a l ( a x i a l and l a t e r a l ) t h r u s t s t a n d ; c o n d i t i o n e d a i r , a t t h e d e s i r e d p r e s s u r e and tem- p e r a t u r e , was s u p p l i e d t h r o u g h t h e i n l e t a i r b e l l - mou th and d u c t i n g t o t h e e n g i n e f a c e . T e s t c e l l c o o l i n g a i r was s u p p l i e d t h r o u g h a c o o l i n g a i r t o r u s a t t h e f o r w a r d end o f t h e t e s t c e l l , and e - h a u s t e r s were a v a i l a b l e t o m a i n t a i n t h e d e s i r e d a l t i t u d e p r e s s u r e i n t h e t e s t c e l l d u r i n g t e s t i n g .

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    An FlOO EMDP ( E n g i n e Model D e r i v a t i v e Pro- gram; P r a t t & W h i t n e y A i r c r a f t d e s i g n a t i o n PW1128) e n g i n e , s e r i a l number X D l l , b u i l d ' 2 was used for t h i s i n v e s t i g a t i o n . T h i s e n g i n e i s a l o w - b y p a s s - r a t i o , h i g h - c o m p r e s s i o n - r a t i o , t w i n - s p o o l t u r b o f a n c o n s i s t i n g o f t h e f o l l o w i n g p a r t s : a t h r e e - s t a g e f a n d r i v e n b y a t w o - s t a g e , l o w - p r e s s u r e t u t - b i n e . a t e n - s t a g e c o m p r e s s o r d r i v e n b y a t w o - s t a g e , a i r - c o o l e d h i g h - p r e s s u r e t u r b i n e , a n a n n u l a r combus- t o r , a m i x e d - f l o w a u g m e n t o r . and a v a r i a b l e a r e a c o n v e r g e n t - d i v e r g e n t e x h a u s t n o z z l e . The augmen- t o r was n o t used d u r i n g t h e t e m p e r a t u r e d i j t o r t i o n t e s t i n g , b u t a n e x h a u s t n o z z l e p l u g was i n c l u d e d

    2

    as p a r t o f t h e i n s t a l l a t i o n t o p r o v i d e e x h a u s t n o z z l e t h r o a t a r e a s s m a l l e r t h a n t h o s e o b t a i n a b l e w i t h t h e s t a n d a r d n o z z l e . The p l u g was 1 4 i n . i n d i a m e t e r and e x t e n d e d u p s t r e a m of t h e e x h a u s t noz- z l e p r i m a r y t h r o a t .

    F lOO(3 ) e n g i n e b u t has a new, advanced f a n d e s i g n , a n i m p r o v e d , h i g h - p r e s s u r e c o m p r e s s o r , a r e c o n - t o u r e d c o m b u s t o r , h i g h e r t e m p e r a t u r e c a p a b i l i t y , h i g h - and l o w - p r e s s u r e t u r b i n e s , and a d i g i t a l e l e c t r o n i c e n g i n e c o n t r o l ( D E E C ) . Compared w i t h t h e F 1 0 0 ( 3 ) f a n , t h e PW1128 f a n i s d e s i g n e d fo r i n c r e a s e d a i r f l o w , p r e s s u r e r a t i o , and e f f i c i e n c y . The b l a d e a s p e c t r a t i o and number o f b l a d e s were r e d u c e d ; and a s h r o u d l e s s t h i r d - s t a g e r o t o r b l a d e , d e s i g n e d for i n c r e a s e d c o r e s u p e r c h a r g i n g , was u s e d . A o n e - p i e c e f a n case w i t h r e m o v a b l e t i p s h r o u d s was i n c o r p o r a t e d , and t h e i n t e r m e d i a t e case a f t o f t h e f a n modu le i n c l u d e d an i n t e g r a ! p r o x i m a t e s p l i t t e r . The fan a l s o has v a r i a b l e i n l e t g u i d e vanes t h a t a r e s c h e d u l e d as a f u n c - t i o n of c o r r e c t e d f a n SDeod.

    The PW1123 e n g i n e i s s i m i l a r 10 t h e p r o d u c t i o n

    A b r e a d b o a r d v e r s i o n o f t h e DEEC was used d u r i n g t h e t e m p e r a t u r e d i s t o r t i o n r e s t s . The b r e a d b o a r d d n i t e n a b l e d t h e o n - l i n e m o d i f i c a t i o n o f s c h e d u l e s , l o g i c , and c o n t r o l loops. The p r i - m a r y uses of t h e DEEC d u r i n g t h e t e s t s were m a i n - t a i n i n g c o n s t a n t c o r r e c t e d f a n speed a n d p r o v i d i n g manual c o n t r o l of t h e e x h a u s t n o z z l e t h r o a t a r e a . A f u r t h e r d e s c r i p t i o n o f t h e DEEC i s c o n t a i n e d i n R e f . 2 1 .

    T e m p e r a t u r e D i s t o r t i o n G e n e r a t o r

    A g a s e o u s - f u e l e d h y d r o g e n b u r n e r was u s e d t o p r o d u c e t h e s t e a d y - s t a t e t e m p e r a t u r e d i s t o r t i o n p a t t e r n s a t t h e e n g i n e i n l e t . H y d r o g e n was used because i t has b o t h good i g n i t i o n c h a r a c t e r i s t i c s a n d r a p i d f l a m e p r o p a g a t i o n speed , r e q u i r e s a low f u e l - t o - a i r r a t i o for a g i v e n t e m p e r a t u r e r i s e , and i s c l e a n b u r n i n g ( g e n e r a t i n g w a t e r v a p o r r a t h e r t h a n p o l l u t a n t s ) . The b u r n e r was i n s t a l l e d i n t h e p l e n u m u p s t r e a m o f t h e i n l e t d u c t b e l l m o u t h ( F i g . 2 ( a ) ) . The b u r n e r , w h i c h was d i v i d e d i n t o f o u r i n d i v i d u a l l y c o n t r o l l e d q u a d r a n t s , h a d t h e c a p a b i l i t y o f b e i n g r o t a t e d 30" i n e i t h e r d i r e c - t i o n f r o m t o p d e a d c e n t e r . Q u a d r a n t s were i d e n t i - f i e d as 1 t h r o u g h 4 s t a r t i n g w i t h t h e u p p e r r i g h t and n u m b e r i n g i n a c l o c k w i s e d i r e c t i o n l o o k i n g u p s t r e a m . E n g i n e i n l e t a i r f l o w was h e a t e d i n s e l e c t e d q u a d r a n t s as i t p a s s e d t h r o u g h t h e b u r n e r .

    Each q u a d r a n t c o n t a i n e d s i x a n n u l a r g u t t e r s s u p p o r t e d b y o n e r a d i a l g u t t e r and s i x c i r c u l a r - t u b e m a n i f o l d s ( o n e i n e a c h a n n u l a r g u t t e r ) w i t h s m a l l h o l e s f o r h y d r o g e n i n j e c t i o n ( F i g . 2 ( b ) ) . The s i x s w i r l - c a n p i l o t b u r n e r s i n e a c h q u a d r a n t i g n i t e d t h e h y d r o g e n f low to e a c h g u t t e r . h y d r o g e n m a n i f o l d l o c a t e d o u t s i d e t h e b u r n e r was c o n n e c t e d b y t u b i n g and r e m o t e l y o p e r a t e d f l o w c o n t r o l v a l v e s t o t h e s i x c i r c u l a r - t u b e m a n i f o l d s i n e a c h q u a d r a n t . The h y d r o g e n m a n i f o l d s were c o n n e c t e d t o t h e h y d r o g e n s u p p l y b y a d d i t i o n a l l e n g t h s of t u b i n g a n d a r e m o t e l y o p e r a t e d m a i n f l o w c o n t r o l v a l v e . With c o n t r o l o f h y d r o g e n f low t o e a c h i n d i v i d u a l q u a d r a n t , c i r c u m f e r e n t i a l d i s - t o r t i o n w i t h e x t e n t s o f go" , 1 8 0 " , 270", and 360" c o u l d b e g e n e r a t e d . A l s o , b y s h u t t i n g o f f h y d r o - gen f l o w t o s e l e c t e d g u t t e r s , hub - and t i p - r a d i a l d i s t o r t i o n p a t t e r n s c o u l d be g e n e r a t e d .

    A

  • I n s t r u m e n t a t i o n

    The i n s t r u m e n t a t i o n u s e d for t h i s t e s t p r o - g ram i s shown i n F i g . 3. A s c h e m a t i c o f t h e e n g i n e and i n s t a l l a t i o n ( F i g . 3 ( a ) ) shows t h e l o c a t i o n o f t h e m e a s u r i n g s t a t i o n s r e l a t i v e t o t h e i n l e t d u c t a n d e n g i n e . T o t a l p r e s s u r e , s t a t i c p r e s s u r e , and t o t a l t e m p e r a t u r e were measured a t each s t a t i o n . The t y p e a n d number o f i n s t r u m e n t a - t i o n p r o b e s a t e a c h m e a s u r i n g s t a t i o n a r e p r e s e n t e d i n F i g . 3 ( b ) . C l o s e - c o u p l e d ( l i m i t e d r e s p o n s e ) p r e s s u r e t r a n s d u c e r s were i n s t a l l e d a t t h e f a n i n l e t , f a n d u c t , h i g h - p r e s s u r e c o m p r e s s o r i n l e t , and h i g h - p r e s s u r e c o m p r e s s o r e x i t . A l i m i t e d number o f h i g h - r e s p o n s e p r e s s u r e measuremen ts were a v a i l a b l e . These measuremen ts were made b y o n e K u l i t e t r a n s d u c e r a t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t a n d o n e K u l i t e t r a n s d u c e r a t t h e h i g h - p r e s s u r e c o m p r e s s o r e x i t .

    P r o c e d u r e

    The e n g i n e was r u n i n i t i a l l y t o e s t a b l i s h b a s e l i n e d a t a f o r t h e f a n w i t h n o i n l e t d i s t o r - t i o n . F o r t h e s e t e s t s , c o n d i t i o n e d a i r was sup- p l i e d t o t h e e n g i n e i n l e t a t a t o t a l p r e s s u r e of 6 . 6 5 p s i a a n d a t o t a l t e m p e r a t u r e of 464 O R . T e s t c e l l a l t i t u d e p r e s s u r e was m a i n t a i n e d a t 4 . 3 6 p s i a . These c o n d i t i o n s c o r r e s p o n d t o a f l i g h t c o n d i t i o n o f 3 0 000 f t w i t h a Mach number o f 0 . 8 ( e n g i n e i n l e t R e y n o l d s number i n d e x o f 0 . 5 2 ) . These same c o n d i t i o n s were used f o r t h e i n l e t d i s t o r t i o n t e s t s w i t h t h e e x c e p t i o n o f t h e 100 p e r c e n t c o r r e c t e d f a n speed d a t a w i t h tempera - t u r e d i s t o r t i o n , where a n i n l e t t e m p e r a t u r e o f 440 O R ( e n g i n e i n l e t R e y n o l d s number i n d e x of 0 . 5 6 ) was m a i n t a i n e d t o a v o i d e n g i n e o v e r t e m p e r a - t u r e . S t a l l d a t a w e r e o b t a i n e d b y r e d u c i n g e x h a u s t n o z z l e t h r o a t a r e a w h i l e m a i n t a i n i n g con- s t a n t c o r r e c t e d f a n speed .

    To o b t a i n f a n maps a n d s t a l l d a t a w i t h s t e a d y - s t a t e I n l e t t e m p e r a t u r e d i s t o r t i o n , t h e m a g n i t u d e a n d e x t e n t o f t h e d i s t o r t i o n p a t t e r n was e s t a b l i s h e d by r e g u l a t i n g h y d r o g e n f l o w t o t h e b u r n e r . F o r a l l t e m p e r a t u r e d i s t o r t i o n p a t t e r n s i n v e s t i g a t e d , t h e t e m p e r a t u r e i n t h e d i s t o r t e d r e g i o n was n o m i n a l l y 50 "R above t h e u n d i s t o r t e d r e g i o n ( A T = 50 O R ) . The c o r r e c t e d f a n speed was s e t a n d h e l d c o n s t a n t b y t h e DEEC w h i l e t h e f a n was f o r c e d t o o p e r a t e a t i n c r e a s i n g l y h i g h e r p r e s - s u r e r a t i o s by m a n u a l l y r e d u c i n g t h e e x h a u s t noz- z l e a r e a i n c r e m e n t a l l y u n t i l e n g i n e s t a l l o c c u r r e d . F o l l o w i n g e a c h i n c r e m e n t a l a r e a r e d u c t i o n , t h e e n g i n e was a l l o w e d t o s t a b i l i z e a n d s t e a d y - s t a t e d a t a w e r e r e c o r d e d . A f t e r e n g i n e s t a l l o c c u r r e d , e n g i n e o p e r a t i o n was r e e s t a b l i s h e d n e a r s t a l l , w i t h t h e same d i s t o r t i o n p a t t e r n and c o r r e c t e d f a n speed ; and t h e t e m p e r a t u r e d i s t o r t i o n p a t t e r n was d e f i n e d b y r e c o r d i n g d a t a a t s e v e r a l b u r n e r r o t a - t i o n s e t t i n g s , i n e f f e c t m o v i n g t h e d i s t o r t i o n p a t t e r n a c r o s s t h e a v a i l a b l e i n s t r u m e n t a t i o n .

    e x t e n t 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 d i s t o r t i o n p a t - t e r n s , 3 6 0 " - e x t e n t h u b - r a d i a l and t i p - r a d i a l p a t - t e r n s , a 1 8 0 " - e x t e n t c i r c u m f e r e n t i a l p r e s s u r e d i s t o r t i o n p a t t e r n , and a 1 8 0 " - e x t e n t 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 d i s t o r t i o n comb ined w i t h a 180"- e x t e n t c i r c u m f e r e n t i a l t o t a l - p r e s s u r e d i s t o r t i o n p r o d u c e d by a s c r e e n u p s t r e a m o f t h e e n g i n e i n l e t .

    S t a l l d a t a were o b t a i n e d f o r 90"- and 180" -

    These i n v e s t i g a t i o n s were c a r r i e d o u t o v e r a r a n g e o f c o r r e c t e d f a n speeds from 8 0 t o 100 p e r c e n t of r a t e d .

    R e s u l t s and D i s c u s s i o n

    f a n s e n s i t i v i t y t o s t e a d y - s t a t e i n l e t t e m p e r a t u r e d i s t o r t i o n , i n l e t p r e s s u r e d i s t o r t i o n , and com- b i n e d i n l e t t e m p e r a t u r e and p r e s s u r e d i s t a r t i o n . The e n g i n e m a n u f a c t u r e r ' s e x a m i n a t i o n of a n a l o g d a t a r e c o r d e d f o r e a c h s t a l l p o i n t r e v e a l e d many i n s t a n c e s i n w h i c h t h e f a n , as i t a p p r o a c h e d t h e s t e a d y - s t a t e s t a l l l i n e , g e n e r a t e d a flOI.4 i n s t a - b i l i t y t h a t e n t e r e d t h e h i g h - p r e s s u r e c o i l p r e s s o r and c a u s e d i t t o s u r g e j u s t b e f o r e , or a t t h e same t i m e a s , t h e f a n . T h i s f low i n s t a b i l i t y was o b s e r v e d o n t h e h i g h - r e s p o n s e p r e s s u r e measurement ( K u l i t e t r a n s d u c e r ) a t t h e h i g h - p r e s s u r e ccmpres- s o r i n l e t when o p e r a t i n g w i t h a n i n l e t t e m p e r a t u r e d i s t o r t i o n p a t t e r n t h a t i n f l u e n c e d t h i s h i g h - r e s p o n s e measuremen t . S i n c e f low i n s t a b i l i t i e s h a v e no t been o b s e r v e d i n o t h e r t e s t s w i t h s i m i l a r t e m p e r a t u r e d i s t o r t i o n g e n e r a t o r s , i t a p p e a r s t h a t n e a r - s t a l l o p e r a t i o n o f t h e f a n i s t h e cause o f t h e f low i n s t a b i 1 i t y .

    T y p i c a l d i s t o r t i o n p a t t e r n s t h a t e x i s t e d a t n e a r - s t a l l c o n d i t i o n s a r e p r e s e n t e d f o r each d i s - t o r t i o n p a t t e r n t e s t e d . Fan maps s h o w i n g t h e e f f e c t o f i n l e t d i s t o r t i o n on t h e s t a l l l i n e a r e i n c l u d e d f o r t h e v a r i o u s d i s t o r t i o n p a t t e r n s .

    T h i s t e s t p r o g r a m was d e s i g n e d t o d e t e r m i n e

    Component Maps With U n i f o r m I n l e t F l o w

    The f a n and h i g h - p r e s s u r e c o m p r e s s o r maps w i t h o u t i n l e t f low d i s t o r t i o n a r e shown i n F i g s . 4 and 5. r e s p e c t i v e l y . Fan s t a l l s were o b t a i n e d a t 80.0, 9 0 . 1 , and 1 0 0 . 2 p e r c e n t o f r a t e d c o r r e c t e d f a n speed b y m a n u a l l y r e d u c i n g e x h a u s t n o z z l e t h r o a t a r e a w h i l e t h e DEEC m a i n t a i n e d c o n s t a n t c o r r e c t e d s p e e d . The s t a l l p o i n t s were e x t r a p o - l a t e d from d a t a p l o t s o f p r e s s u r e r a t i o and c o r - r e c t e d a i r f l o w a s a f u n c t i o n o f e x h a u s t n o z z l e t h r o a t a r e a . The h i g h - p r e s s u r e c o m p r e s s o r map ( F i g . 5) was g e n e r a t e d from d a t a o b t a i n e d i n a n o t h e r t e s t p r o g r a m w i t h t h e same e n g i n e where a n in f low b l e e d s y s t e m was u s e d t o b a c k p r e s s u r e t h e c o m p r e s s o r a t c o n s t a n t c o r r e c t e d speed . The p r o g r a m i n w h i c h t h e h i g h - p r e s s u r e c o m p r e s s o r map was g e n e r a t e d was i n t e r e s t e d p r i m a r i l y i n s u b i d l e speed o p e r a t i o n , so t h e speed r a n g e s of t h e two maps do n o t c o i n c i d e : t h e h i g h e s t c o r r e c t e d h i g h - p r e s s u r e c o m p r e s z o r speed matches a p p r o x i m a t e l y w i t h t h e l o w e s t c o r r e c t e d f a n speed t e s t e d .

    I n l e t T e m p e r a t u r e P r o f i l e s

    Examp les o f t y p i c a l f a n and h i g h - p r e s s u r e c o m p r e s s o r i n l e t t e m p e r a t u r e d i s t o r t i o n p r o f i l e s a r e shown i n F i g s . 6 t o 9 . T a b l e s 1 and 2 c o n t a i n a c o m p l e t e d e s c r i p t i o n o f a l l t h e t e m p e r a t u r e d i s - t o r t i o n p a t t e r n s t e s t e d . The c i r c u m f e r e n t i a l one - p e r - r e v o l u t i o n a n d h u b - r a d i a l p a t t e r n s ( F i g s . 6 t c 8) w e r e r e c o r d e d a t 8 0 p e r c e n t c o r r e c t e d f a n speed w i t h t h e e x h a u s t n o z z l e t h r o a t a r e a a p p r o x i m a t e l y 0.1 f t 2 l a r g e r t h a n was r e q u i r e d t o i n i t i a t e s t a l l . The t i p - r a d i a l p a t t e r n ( F i g . 9 ) was r e c o r d e d a t 9 0 p e r c e n t c o r r e c t e d f a n speed w i t h t h e e x h a u s t n o z z l e 0 . 1 6 f t2 l a r g e r t h a n r e q u i r e d f o r s t a l l .

    3

  • The s t e a d y - s t a t e s p a t i a l t e m p e r a t u r e d i s t o r - t i o n p a t t e r n s a r e d e s c r i b e d i n t e r m s o f c i r c u m f e r - e n t i a l e x t e n t , c i r c u m f e r e n t i a l i n t e n s i t y , and r a d i a l i n t e n s i t y . These d e s c r i p t o r s , s i m i l a r to t h o s e d e f i n e d f o r i n l e t p r e s s u r e d i s t o r t i o n i n R e f s . 22 and 23 , a r e o b t a i n e d b y s u b s t i t u t i n g h i g h t e m p e r a t u r e f o r low p r e s s u r e as t n e d e s t a b i l i z i n g f a c t o r . The e x t e n t d e s c r i p t o r i s an i n d i c a t i o n o f t h e c i r c u m f e r e n t i a l s i z e o f t h e h i g h - t e m p e r a t u r e r e g i o n , and t h e i n t e n s i t y d e s c r i p t o r s a r e i n d i c a - t i o n s o f t h e m a g n i t u d e o f t h e t e m p e r a t u r e d i s t o r - t i o n . The d i s t o r t i o n p a t t e r n e x t e n t i s d e f i n e d as t h e c i r c u m f e r e n t i a l e x t e n t o f t h e h i g h - t e m p e r a t u r e r e g i o n o b t a i n e d from a l i n e a r i n t e r p o l a t i o n o f t h e c i r c u m f e r e n t i a l p r o f i l e and i t s i n t e r s e c t i o n w i t h t h e a v e r a g e t e m p e r a t u r e o f t h e p r o f i l e . The c i r - c u m f e r e n t i a l i n t e n s i t y , ( d T C / T ) , i s d e f i n e d as t h e d i f f e r e n c e be tween t h e h i g h - t e m p e r a t u r e r e g i o n a v e r a g e t e m p e r a t u r e and t h e p r o f i l e a v e r a g e temper - a t u r e r a t i o e d t o t h e p r o f i l e a v e r a g e t e m p e r a t u r e . The r a d i a l t e m p e r a t u r e d i s t o r t i o n i n t e n s i t y , ( d T R / T ) , i s d e f i n e d as t h e d i f f e r e n c e b e t w e e n t h e maximum h i g h t e m p e r a t u r e i n t h e r a d i a l p r o f i l e and t h e p r o f i l e a v e r a g e t e m p e r a t u r e r a t i o e d t o t h e p r o f i l e a v e r a g e t e m p e r a t u r e .

    b y b u r n i n g i n o n e q u a d r a n t of t h e h y d r o g e n b u r n e r i s shown i n F i g . 6 . Based o n t h e a b o v e d e f i n i - t i o n s , t h e d i s t o r t i o n a t t h e f a n i n l e t has an e x t e n t of 132" w i t h a c i r c u m f e r e n t i a l i n t e n s i t y o f 0 . 0 4 5 and a r a d i a l i n t e n s i t y o f 0.006. The c i r - c u m f e r e n t i a l i n t e n s i t y does n o t r e f l e c t t h e t r u e v a l u e , w h i c h may be s l i g h t l y h i g h e r , b e c a u s e t h e i n s t r u m e n t a t i o n was l o c a t e d s u c h t h a t e v e n w i t h b u r n e r r o t a t i o n p e a k t e m p e r a t u r e s were n o t meas- u r e d . The shape o f t h e a c t u a l p a t t e r n a t t h e f a n i n l e t i s more l i k e t h a t shown f o r t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t ( F i g . 6 ( b ) ) . The t e m p e r a t u r e d i s t o r t i o n p a t t e r n , w h i c h f o l l o w s a p a r t i c l e p a t h t h r o u g h t h e f a n , i s r o t a t e d a p p r o x i m a t e l y 7 0 " i n t h e d i r e c t i o n of rotor r o t a t i o n as i t p a s s e s t h r o u g h t h e f a n . A t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t , t h e d i s t o r t i o n has a c i r c u m f e r e n t i a l e x t e n t o f 118" w i t h c i r c u m f e r e n t i a l a n d r a d i a l i n t e n s i - t i e s o f 0 . 0 3 8 a n d 0.011, r e s p e c t i v e l y .

    The s p a t i a l t e m p e r a t u r e d i s t o r t i o n p r o d u c e d

    F i g u r e 7 shows t h e t e m p e r a t u r e d i s t o r t i o n p r o f i l e s p r o d u c e d b y b u r n i n g i n two a d j a c e n t quad- r a n t s o f t h e h y d r o g e n b u r n e r i n a n a t t e m p t t o c r e - a t e a 1 8 0 " - e x t e n t c i r c u m f e r e n t i a l p a t t e r n . The p r o f i l e a t t h e f a n i n l e t has a n e x t e n t o f 180" w i t h a c i r c u m f e r e n t i a l i n t e n s i t y o f 0 . 0 4 7 and a r a d i a l i n t e n s i t y o f 0.009. H e r e a g a i n , t h e tem- p e r a t u r e d i s t o r t i o n p a t t e r n r o t a t e s a p p r o x i m a t e l y 70" w h i l e p a s s i n g t h r o u g h t h e f a n . A t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t t h e p r o f i l e has a n e x t e n t o f 192" . The a c t u a l e x t e n t , h o w e v e r , i s p r o b a b l y c l o s e r t o 1 8 0 ° , b u t s u f f i c i e n t i n s t r u m e n - t a t i o n was n o t a v a i l a b l e t o c o m p l e t e l y d e f i n e t h e p r o f i l e a t t h i s s t a t i o n . The c i r c u m f e r e n t i a l and r a d i a l i n t e n s i t i e s a t t h e h i g h - p r e s s u r e compres - s o r i n l e t a r e 0 . 0 4 3 and 0.010, r e s p e c t i v e l y . Based o n t h e c i r c u m f e r e n t i a l i n t e n s i t i e s i n T a b l e 1, t h e d i s t o r t i o n a m p l i t u d e a t t h e f a n i n l e t i s a t t e n u a t e d b y a n a v e r a g e o f a p p r o x i m a t e l y 15 p e r c e n t b e f o r e i t r e a c h e s t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t .

    The c i r c u m f e r e n t i a l and r a d i a l t e m p e r a t u r e p r o f i l e s a t t h e f a n a n d h i g h - p r e s s u r e c o m p r e s s o r i n l e t s for a h u b - r a d i a l d i s t o r t i o n a r e p r e s e n t e d i n F i g . 8 . The c i r c u m f e r e n t i a l p r o f i l e s e x h i b i t

    m u l t i p l e low i n t e n s i t y ( l e s s t h a n 1 p e r c e n t ) h i g h - t e m p e r a t u r e r e g i o n s . The d i s t o r t i o n d e s c r i p t o r s f o r t h i s t y p e o f m u l t i p l e - p e r - r e v o l u t i o n ( M P R ) d i s t o r t i o n p a t t e r n a r e a l s o s i m i l a r t o t h o s e d e f i n e d i n R e f s . 22 and 2 3 . The e x t e n t and i n t e n - s i t y o f t h e c i r c u m f e r e n t i a l d i s t o r t i o n c o r r e s p o n d to t h e r e g i o n t h a t has t h e h i g h e s t p r o d u c t o f e x t e n t and i n t e n s i t y . A l s o i n c l u d e d i n t h e p a t - t e r n d e s c r i p t i o n i s an M P R f a c t o r w h i c h i s d e f i n e d as t h e number o f e q u i v a l e n t h i g h - t e m p e r a t u r e r e g i o n s based o n t h e r a t i o o f t h e sum o f t h e p r o - d u c t s o f t h e e x t e n t s and i n t e n s i t i e s f o r each h i g h - t e m p e r a t u r e r e g i o n , t o t h e r e g i o n w i t h t h e l a r g e s t p r o d u c t o f e x t e n t and i n t e n s i t y . Based o n t h e s e d e s c r i p t o r s and t h o s e d e f i n e d p r e v i o u s l y , t h e c i r c u m f e r e n t i a l d i s t o r t i o n a t t h e f a n i n l e t has a n e x t e n t o f 100" d e g r e e s , a c i r c u m f e r e n t i a l i n t e n s i t y o f 0.008, and a n MPR f a c t o r o f 1 . 5 6 3 . The r a d i a l t e m p e r a t u r e d i s t o r t i o n i n t e n s i t y i s 0 . 0 7 2 . A t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t ( F i g . 8 ( b ) ) , t h e r a d i a l i n t e n s i t y i s 0 . 0 6 9 and t h e c i r c u m f e r e n t i a l e x t e n t i s 108" w i t h a n i n t e n s i t y o f 0.007 and a n MPR o f 1 . 0 8 5 . A l t h o u g h t h i s i s an a t t e n u a t i o n o f a p p r o x i m a t e l y 4 p e r c e n t b e t w e e n t h e f a n i n l e t and t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t , t h e a t t e n u a t i o n o f r a d i a l t e m p e r a t u r e d i s t o r t i o n for a l l t h e h u b - r a d i a l p a t t e r n s l i s t e d i n T a b l e 1 r a n g e s from 4 t o 17 p e r c e n t .

    The t i p - r a d i a l t e m p e r a t u r e d i s t o r t i o n p a t t e r n ( F i g . 9) e x h i b i t s t h e same c i r c u m f e r e n t i a l c h a r a c - t e r i s t i c s as t h e h u b - r a d i a l p a t t e r n i n t h a t a low- i n t e n s i t y MPR d i s t o r t i o n e x i s t s a t t h e f a n and h i g h - p r e s s u r e c o m p r e s s o r i n l e t s . The r a d i a l d i s - t o r t i o n a t t h e f a n i n l e t i s c o n f i n e d t o t h e b l a d e - t i p r e g i o n a n d , as e x p e c t e d , i s n o t p r e s e n t a t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t . A t t h e f a n i n l e t , t h e d i s t o r t i o n has a n e x t e n t o f 139" , a c i r c u m f e r - e n t i a l i n t e n s i t y o f 0.009, and a n MPR of 1 . 3 5 3 . The r a d i a l i n t e n s i t y i s 0 . 0 3 4 . The d i s t o r t i o n t r a n s f e r r e d t h r o u g h t h e f a n t o t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t has a n e x t e n t o f 1 0 7 " , a n MPR o f 1 . 8 4 4 , and c i r c u m f e r e n t i a l and r a d i a l i n t e n s i t i e s o f 0 . 0 1 0 and 0 . 0 1 3 , r e s p e c t i v e l y .

    I n g e n e r a l , t e m p e r a t u r e d i s t o r t i o n p a t t e r n s p r o d u c e d b y t h e h y d r o g e n b u r n e r w e r e of t h e t y p e d e s i r e d . The c i r c u m f e r e n t i a l p a t t e r n s e x h i b i t e d v e r y s m a l l r a d i a l componen ts and , l i k e w i s e , t h e r a d i a l t e m p e r a t u r e d i s t o r t i o n p a t t e r n s c o n t a i n e d v e r y l i t t l e c i r c u m f e r e n t i a l d i s to r t i on .

    C i r c u m f e r e n t i a l I n l e t T e m p e r a t u r e D i s t o r t i o n

    C i r c u m f e r e n t i a l o n e - p e r - r e v o l u t i o n i n l e t t e m p e r a t u r e d i s t o r t i o n p a t t e r n s of two e x t e n t s were g e n e r a t e d b y h e a t i n g t h e i n l e t a i r f l o w w i t h e i t h e r o n e b u r n e r q u a d r a n t or two a d j a c e n t b u r n e r q u a d r a n t s . The t e s t s w e r e c o n d u c t e d f o r b o t h e x t e n t s w i t h t h e d i s t o r t i o n i n t h e t o p and b o t t o m r e g i o n s o f t h e f a n i n l e t i n a n a t t e m p t t o d e t e r - m i n e t h e e f f e c t o n f a n s t a b i l i t y o f t h e l o c a t i o n o f f a n i n l e t t e m p e r a t u r e s e n s o r s u s e d f o r s c h e d u l - i n g v a r i a b l e g e o m e t r y . I n a l l c a s e s t h e h e a t e d r e g i o n s w e r e a p p r o x i m a t e l y 50 " R h o t t e r t h a n u n h e a t e d r e g i o n s , w h i c h r e s u l t e d i n d i s t o r t i o n i n t e n s i t i e s t h a t were n e a r l y c o n s t a n t t h r o u g h o u t t h e t e s t p r o g r a m . D e s c r i p t o r s o f a l l t h e 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 d i s t o r t i o n p a t t e r n s t e s t e d a r e shown i n T a b l e 1 . The e n t r i e s m i s s i n g from T a b l e 1 were n o t a v a i l a b l e because p r o f i l e i n f o r - m a t i o n ( b a s e d o n b u r n e r r o t a t i o n d a t a ) was n o t

  • r e c o r d e d . I n t h e c a s e where h i g h - p r e s s u r e compres- s o r i n l e t c o n d i t i o n s a r e m i s s i n g ( q u a d r a n t 2 ) , t h e i n s t r u m e n t a t i o n a t t h a t s t a t i o n was i n s u f f i c i e n t t o d e t e c t t h e d i s t o r t i o n p a t t e r n . W i t h t h e s m a l l v a r i a t i o n s i n e x t e n t and i n t e n s i t y among t h e p a t - t e r n s , d a t a c o r r e l a t i o n s c o u l d b e made b y assum- i n g a m i s s i n g e n t r y c o u l d be r e p l a c e d b y t h e v a l u e above i t .

    The r e s u l t s o f o p e r a t i o n w i t h f a n i n l e t 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 d i s t o r t i o n i n d i c a t e d t h a t as t h e f a n a p p r o a c h e d i t s s t e a d y - s t a t e s t a l l l i n e a f low i n s t a b i l i t y was g e n e r a t e d . The f low i n s t a - b i l i t y g e n e r a t e d b y t h e f a n c a u s e d t h e h i g h - p r e s s u r e c o m p r e s s o r t o s u r g e j u s t b e f o r e , or n e a r l y a t t h e same t i m e a s , t h e f a n . T a b l e 1 l i s t s t h e h i g h - p r e s s u r e c o m p r e s s o r c o r r e c t e d speeds o f t h e l a s t s t e a d y - s t a t e d a t a p o i n t r e c o r d e d b e f o r e s t a l l , whereas t h e f a n speeds a r e t h e c o n s t a n t v a l u e s m a i n t a i n e d d u r i n g t h e e x h a u s t n o z z l e a r e a r e d u c t i o n . I t s h o u l d be n o t e d t h a t , a l t h o u g h c o r - r e c t e d f a n speed was h e l d c o n s t a n t d u r i n g t h e noz - z l e a r e a r e d u c t i o n , t h e r e m a t c h o f t h e f a n and c o m p r e s s o r r e s u l t e d i n a n i n c r e a s e o f c o r r e c t e d h i g h - p r e s s u r e c o m p r e s s o r speed .

    The f a c t t h a t t h e f a n was o p e r a t i n g n e a r s t a l l p r i o r t o e n g i n e s u r g e c a n be i l l u s t r a t e d b y u s i n g s i m p l e p a r a l l e l c o m p r e s s o r t h e o r y . T h i s t h e o r y assumes t h a t a c o m p r e s s o r c a n be s e p a r a t e d i n t o a d i s c r e t e number o f p a r a l l e l f low p a t h s o p e r a t i n g a t t h e same m e c h a n i c a l speed and e x i t s t a t i c p r e s s u r e , b u t w i t h d i f f e r e n t i n l e t t o t a l p r e s s u r e s and t e m p e r a t u r e s . The p e r f o r m a n c e of e a c h segment i s assumed t o be t h e same as t h a t o b t a i n e d w i t h un i form f low c o n d i t i o n s a t t h e seg- m e n t i n l e t . Each segment may o p e r a t e w i t h a d i f - f e r e n t c o r r e c t e d speed , o p e r a t i n g p o i n t , and s t a l l m a r g i n . S t a l l i n i t i a t e s when a n y o f t h e segmen ts i s f o r c e d t o o p e r a t e above t h e s t a l l l i n e d e f i n e d w i t h u n i f o r m i n l e t f low.

    The e x c u r s i o n o f t h e f a n o p e r a t i n g p o i n t d u r - i n g t h e e x h a u s t n o z z l e a r e a r e d u c t i o n , w i t h a 1 8 0 " - e x t e n t c i r c u m f e r e n t i a l d i s t o r t i o n , i s shown i n F i g . 10. The d i s t o r t i o n p a t t e r n d e s c r i p t o r s a r e g i v e n i n T a b l e 1 as p a t t e r n number 7 . Fan speed was h e l d c o n s t a n t a t 9 1 . 3 p e r c e n t c o r r e c t e d as shown b y t h e a v e r a g e o p e r a t i n g p o i n t s of . F i g . 10. D u r i n g t h i s e x h a u s t nozzle a r e a r e d u c - t i o n , t h e c o r r e c t e d speed o f t h e h i g h - p r e s s u r e c o m p r e s s o r i n c r e a s e d f r o m 9 4 . 8 t o 9 6 . 0 p e r c e n t , w h i l e t h e a v e r a g e h i g h - p r e s s u r e c o m p r e s s o r o p e r a t - i n g p o i n t moved a l o n g i t s o p e r a t i n g l i n e . The f a n o p e r a t i n g p o i n t s a r e p l o t t e d o n t h e component map o b t a i n e d w i t h u n i f o r m i n l e t f low. S p l i t t i n g t h e f a n i n t o two segments u s i n g p a r a l l e l c o m p r e s s o r t h e o r y r e s u l t e d i n t h e h o t - s i d e a n d c o l d - s i d e c o r - r e c t e d f a n speed l i n e s shown i n F i g . 10. The h o t and c o l d s i d e s o p e r a t e a t t h e same p r e s s u r e r a t i o as t h e a v e r a g e p o i n t s , b u t w i t h d i f f e r e n t i n l e t t e m p e r a t u r e s and , t h e r e f o r e , d i f f e r e n t c o r r e c t e d speeds . T h i s f o r c e s t h e segment w i t h t h e h igh i n l e t t e m p e r a t u r e t o a p p r o a c h t h e s t e a d y - s t a t e s t a l l l i n e as t h e e x h a u s t n o z z l e a r e a i s r e d u c e d . F o r t h e a v e r a g e s t e a d y - s t a t e s t a l l p o i n t ( f l a g g e d symbol i n F i g . l o ) , t h e h e a t e d p o r t i o n o f t h e f a n i s o p e r a t i n g above t h e s t e a d y - s t a t e s t a l l l i n e w i t h u n i f o r m i n l e t f low.

    Fan maps s h o w i n g t h e e f f e c t of s i n g l e quad- r a n t b u r n e r h e a t i n g o n f a n p e r f o r m a n c e a r e p r e - s e n t e d i n F i g s . 1 1 and 12 . The r e s u l t s shown i n

    F i g . 11 o c c u r e d w i t h t h e t e m p e r a t u r e d i s t o r t i o n i n q u a d r a n t 4 a t t h e f a n i n l e t ( u n h e a t e d i n l e t t e m p e r a t u r e s e n s o r s ) whereas F i g . 12 p r e s e n t s r e s u l t s w i t h h e a t i n g i n q u a d r a n t 2 ( h e a t e d i n l e t t e m p e r a t u r e s e n s o r s ) . I n b o t h f i g u r e s , i t i s e v i - d e n t t h a t t h e i n l e t t e m p e r a t u r e d i s t o r t i o n c a u s e s a l o s s i n f a n s t a l l p r e s s u r e r a t i o (measured a t c o n s t a n t c o r r e c t e d a i r f l o w ) a t a l l s p e e d s . I n F i g . 1 1 t h e loss i n f a n s t a l l p r e s s u r e r a t i o a t 78 .9 , 88 .9 , and 9 9 . 0 p e r c e n t c o r r e c t e d speed i s 8 . 1 , 6 . 6 , a n d 6 . 4 p e r c e n t r e s p e c t i v e l y , for a c i r - c u m f e r e n t i a l i n l e t t e m p e r a t u r e d i s t o r t i o n w i t h a n e x t e n t of 133" and a m a g n i t u d e of 4 . 5 p e r c e n t ( p a t t e r n s 1 , 2 , a n d 3 o f T a b l e 1 ) . From F i g . 12 , t h e l o s s of f a n s t a l l p r e s s u r e r a t i o a t 82 .7 and 9 2 . 9 p e r c e n t c o r r e c t e d speed i s 9 . 4 and 9 . 3 p e r c e n t r e s p e c t i v e l y , for p a t t e r n s 4 and 5 o f T a b l e 1 .

    o n f a n p e r f o r m a n c e of o p e r a t i n g w i t h h e a t i n g i n two a d j a c e n t q u a d r a n t s o f t h e b u r n e r . When t h e i n l e t t e m p e r a t u r e s e n s o r s a r e u n h e a t e d ( F i g . 1 3 ) , t h e i n l e t d i s t o r t i o n ( p a t t e r n s 9 t o 11 o f T a b l e 1 ) causes f a n s t a l l p r e s s u r e r a t i o l o s s e s of 1 3 . 2 , 9 . 5 , a n d 6 . 3 p e r c e n t a t 78 .0 , 8 8 . 0 , and 9 7 . 7 p e r c e n t c o r r e c t e d speed r e s p e c t i v e l y . W i t h t h e i n l e t t e m p e r a t u r e s e n s o r s h e a t e d b y t h e i n l e t t e m p e r a t u r e d i s t o r t i o n ( F i g . 1 4 ) , t h e r e s u l t i n g loss i n f a n s t a l l p r e s s u r e r a t i o i s 10.6, 8 . 7 , and 6 . 6 p e r c e n t a t 8 1 . 1 , 9 1 . 3 , and 102.0 p e r c e n t c o r r e c t e d speed r e s p e c t i v e l y .

    A s m e n t i o n e d e a r l i e r , one o f t h e o b j e c t i v e s of t h e t e s t p r o g r a m was t o d e t e r m i n e t h e e f f e c t o f f a n i n l e t t e m p e r a t u r e s e n s o r l o c a t i o n o n s t a - b i l i t y . When t h e s e n s o r s d e t e c t e i t h e r t h e h o t or c o l d p a r t o f t h e d i s t o r t e d f low, t h e c o n t r o l a d j u s t s v a r i a b l e g e o m e t r y a c c o r d i n g l y ; and changes t h e f a n s t a l l m a r g i n d i f f e r e n t l y from when t h e s e n s o r s d e t e c t t h e a v e r a g e t e m p e r a t u r e . PW1128 e n g i n e h a s i n l e t t e m p e r a t u r e s e n s o r s l o c a t - e d i n t h e b o t t o m h a l f o f t h e f a n i n l e t . B o t h s i n - g l e q u a d r a n t a n d a d j a c e n t q u a d r a n t h e a t i n g was t e s t e d w i t h t h e d i s t o r t i o n i n t h e t o p a n d b o t t o m a t t h e f a n i n l e t . C o m p a r i s o n o f F i g . 13 w i t h F i g . 1 4 shows t h a t , for a 1 8 0 " - e x t e n t t e m p e r a t u r e d i s t o r t i o n a t t h e low c o r r e c t e d f a n speeds ( 7 8 . 0 t o 81 .1 p e r c e n t ) , a g r e a t e r l o s s i n s t a l l p r e s - s u r e r a t i o occurs when t h e s e n s o r s a r e l o c a t e d o u t s i d e t h e t e m p e r a t u r e d i s t o r t i o n ( u n h e a t e d ) . S i m i l a r r e s u l t s h a v e b e e n r e p ~ r t e d . ~

    S i m l l a r l y , F i g s . 1 3 a n d 14 p r e s e n t t h e e f f e c t

    The

    R a d i a l I n l e t T e m p e r a t u r e D i s t o r t i o n

    The hub- a n d t i p - r a d i a l i n l e t t e m p e r a t u r e d i s t o r t i o n p a t t e r n s t h a t were t e s t e d w i t h t h e PW1128 e n g i n e a r e d e s c r i b e d i n T a b l e 2 . B o t h t y p e s of r a d i a l p a t t e r n s e x h i b i t low l e v e l s o f MPR c i r c u m f e r e n t i a l d i s t o r t i o n s i m i l a r t o t h a t shown i n F i g s . 8 and 9 . The t i p - r a d i a l p a t t e r n i s not t r a n s f e r r e d t o t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t , whereas t h e h u b - r a d i a l d i s t o r t i o n p a s s e s t h r o u g h t h e f a n and a p p e a r s a t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t , a t t e n u a t e d from 4 p e r c e n t a t t h e low speed t o 17 p e r c e n t a t t h e h i g h e s t speed t e s t e d . E n t r i e s not a p p e a r i n g i n T a b l e 2 w e r e o m i t t e d b e c a u s e p a t t e r n d e f i n i t i o n from b u r n e r r o t a t i o n s was n o t r e c o r d e d , and t h e l i m i t e d i n s t r u - m e n t a t i o n a t b o t h f a n a n d h i g h - p r e s s u r e c o m p r e s s o r i n l e t s t a t i o n s was i n s u f f i c i e n t t o a c c u r a t e l y d e f i n e t h e l o w - l e v e l MPR c i r c u m f e r e n t i a l c o n t e n t .

    5

  • A s was t h e case w i t h c i r c u m f e r e n t i a l t empera - t u r e d i s t o r t i o n , r a d i a l i n l e t t e m p e r a t u r e d i s t o r - t i o n s r e s u l t e d i n a l o s s i n f a n s t a l l p r e s s u r e r a t i o . I n some i n s t a n c e s , a f low i n s t a b i l i t y gen- e r a t e d b y t h e f a n o p e r a t i n g n e a r s t a l l ( s i m i l a r t o t h a t r e c o r d e d w i t h 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 d i s t o r t i o n ) was o b s e r v e d a n d c a u s e d t h e h i g h - p r e s s u r e c o m p r e s s o r t o s t a l l j u s t b e f o r e , or n e a r t h e same t i m e a s , t h e f a n . The h i g h - p r e s s u r e com- p r e s s o r speeds l i s t e d i n T a b l e 2 a r e t h o s e o f t h e l a s t s t e a d y - s t a t e d a t a p o i n t r e c o r d e d b e f o r e s t a l l .

    The r e s u l t s w i t h t i p - r a d i a l t e m p e r a t u r e d i s - t o r t i o n a r e shown o n t h e f a n map o f F i g . 1 5 . Fan s t a l l s o c c u r r e d a t c o n s t a n t c o r r e c t e d f a n speeds o f 8 0 . 8 and 9 1 . 2 p e r c e n t . A t 9 6 . 2 p e r c e n t speed , a f low i n s t a b i l i t y g e n e r a t e d b y t h e f a n was n o t o b s e r v e d , b u t i t a p p e a r s t h a t s t a l l was i n i t i a t e d i n t h e h i g h - p r e s s u r e c o m p r e s s o r ; t h e r e f o r e , a f a n s t a l l p o i n t i s n o t i n c l u d e d f o r t h e h i g h c o r r e c t e d speed , a l t h o u g h i t i s b e l i e v e d t h e f a n was o p e r a t - i n g c l o s e t o i t s s t e a d y - s t a t e l i m i t . The h i g h - p r e s s u r e c o m p r e s s o r s t a l l a t t h e h i g h speed may be due t o t h e i n c r e a s e d c i r c u m f e r e n t i a l i n t e n s i t y o f d i s t o r t i o n p a t t e r n 3 a t t h e h i g h - p r e s s u r e compres - s o r i n l e t ( 0 . 0 1 6 compared t o 0.010 or l e s s for p a t t e r n s 1 a n d 2 ) , s i n c e t h e r a d i a l c o n t e n t a t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t i s a b o u t t h e same as p a t t e r n 2 . F o r t h e f a n , t h e t i p - r a d i a l t emper - a t u r e d i s t o r t i o n a t 8 0 . 8 p e r c e n t speed ( p a t t e r n 1 , T a b l e 2 ) r e s u l t e d i n a l o s s o f s t a l l p r e s s u r e r a t i o ( A P R S ) o f 10.6 p e r c e n t , d e f i n e d a t c o n s t a n t c o r r e c t e d a i r f l o w as i n R e f s . 22 a n d 2 3 . A t 9 1 . 2 p e r c e n t c o r r e c t e d speed , p a t t e r n 2 o f T a b l e 2 c a u s e d a APRS o f 5 .7 p e r c e n t .

    R e s u l t s w i t h 3 6 0 " - e x t e n t h u b - r a d i a l t empera - t u r e d i s t o r t i o n a r e shown i n F i g . 1 6 . A t e a c h speed , s t a l l i n i t i a t e d i n t h e f a n w i t h d i s t o r t i o n p a t t e r n s 4, 5 , a n d 6 ( T a b l e 2 ) . The h u b - r a d i a l t e m p e r a t u r e d i s t o r t i o n c a u s e d f a n s t a l l p r e s s u r e r a t i o l o s s e s o f 5 . 0 p e r c e n t a t 7 8 . 4 p e r c e n t c o r - r e c t e d speed , 6 . 1 p e r c e n t a t 8 8 . 3 p e r c e n t c o r r e c t e d speed , a n d 5 . 3 p e r c e n t a t 9 8 . 4 p e r c e n t c o r r e c t e d speed .

    C i r c u m f e r e n t i a l I n l e t T o t a l - P r e s s u r e D i s t o r t i o n

    The e n g i n e was t e s t e d w i t h c i r c u m f e r e n t i a l

    The p r e s s u r e i n l e t t o t a l - p r e s s u r e d i s t o r t i o n a t c o r r e c t e d f a n speeds o f 90.2 a n d 1 0 0 . 2 p e r c e n t . d i s t o r t i o n was p r o d u c e d by a 180" s e c t o r o f 5 1/2-mesh s c r e e n ( 0 . 0 6 3 - i n . - d i a m w i r e ) i n s t a l l e d i n t h e bottom h a l f o f t h e i n l e t d u c t u p s t r e a m o f t h e f a n i n l e t . The t o t a l - p r e s s u r e p r o f i l e s a t t h e f a n i n l e t f o r t h e l a s t , s t e a d y - s t a t e d a t a p o i n t s r e c o r d e d p r i o r t o s t a l l a r e shown i n F i g . 17 . Based o n t h e me thods o f R e f s . 22 and 2 3 f o r c a l c u l a t i n g p r e s s u r e d i s t o r t i o n d e s c r i p t o r s , t h e p a t t e r n s e x h i b i t c i r c u m f e r e n t i a l e x t e n t s o f 183" a t b o t h speeds w i t h c i r c u m f e r e n t i a l i n t e n s i - t i e s (AP /P) o f 0 . 0 4 2 a t t h e low speed ( F i g . 1 7 ( a ) ) a n d 0 . 0 7 2 a t t h e h i g h speed ( F i g . 1 7 ( b ) ) . F o r both speeds , n o s i g n i f i c a n t r a d i a l t o t a l - p r e s s u r e d i s t o r t i o n e x i s t e d . The i n s t r u m e n t a t i o n a t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t was n o t a d e q u a t e t o d e f i n e t h e p r o f i l e a t t h a t s t a t i o n n o r t o d e t e r - m i n e t h e p r e s s u r e d i s t o r t i o n t r a n s f e r c h a r a c t e r i s - t i c s o f t h e f a n .

    The e - f f e c t o f i n l e t t o t a l - p r e s s u r e d i s t o r t i o n o n f a n s t a b i l i t y i s shown s u p e r i m p o s e d o n t h e u n i - form i n l e t f low f a n map i n F i g . 18. As was t h e

    c a s e w i t h i n l e t t e m p e r a t u r e d i s t o r t i o n , t h e f a n s t a l l l i n e w i t h i n l e t p r e s s u r e d i s t o r t i o n was d e f i n e d b y r e d u c i n g e x h a u s t n o z z l e t h r o a t a r e a w h i l e m a i n t a i n i n g c o r r e c t e d f a n speed c o n s t a n t . A t 9 0 . 2 p e r c e n t c o r r e c t e d f a n speed, t h e t o t a l - p r e s s u r e d i s t o r t i o n ( F i g . 1 7 ( a ) ) r e s u l t e d i n a 6 . 2 p e r c e n t l o s s o f s t a l l p r e s s u r e r a t i o ( A P R S ) . The e f f e c t o f t h e p r e s s u r e d i s t o r t i o n a t 1 0 0 . 2 p e r c e n t c o r r e c t e d speed was a n 8 . 3 p e r c e n t loss i n s t a l l p r e s s u r e r a t i o .

    Combined T e m p e r a t u r e and P r e s s u r e D i s t o r t i o n

    Two c o n f i g u r a t i o n s of comb ined t e m p e r a t u r e and p r e s s u r e d i s t o r t i o n were t e s t e d . One was w i t h d i a m e t r i c a l l y opposed 1 8 0 " - e x t e n t s e c t o r s ( p r e s - s u r e d i s t o r t i o n o v e r t h e b o t t o m h a l f o f t h e f a n i n l e t ) , a n d t h e o t h e r had t h e 1 8 0 " - e x t e n t s e c t o r s o f t e m p e r a t u r e a n d p r e s s u r e d i s t o r t i o n t o g e t h e r o v e r t h e b o t t o m h a l f o f t h e f a n i n l e t . The i n s t r u m e n t a t i o n was a d e q u a t e i o d e f i n e t h e p r e s - s u r e d i s t o r t i o n p r o f i l e s a t each speed , b u t t h e b u r n e r was n o t r o t a t e d t o d e f i n e t h e t e m p e r a t u r e d i s t o r t i o n p r o f i l e s . I t s h o u l d be assumed t h a t t h e t e m p e r a t u r e d i s t o r t i o n p a t t e r n s d e s c r i b e d i n T a b l e 1 ( p a t t e r n s 6 t o 8 for t h e d i s t o r t i o n s t o g e t h e r a n d p a t t e r n s 9 t o 11 for t h e d i s t o r t i o n s opposed) e x i s t e d d u r i n g t h e s e comb ined d i s t o r t i o n t e s t s , s i n c e h y d r o g e n f low to t h e b u r n e r was a d j u s t e d t o e s s e n t i a l l y t h e same v a l u e s as t h o s e u s e d t o p r o d u c e t h e p a t t e r n s o f T a b l e 1 .

    e f f e c t o n h i g h - p r e s s u r e c o m p r e s s o r s t a b i l i t y when t h e d i s t o r t e d s e c t o r s were t o g e t h e r . R e s u l t s o f a t t e m p t s t o map t h e f a n w i t h t h e d i s t o r t i o n s t o g e t h e r a r e shown i n F i g . 1 9 . A n a l y s i s b y t h e e n g i n e m a n u f a c t u r e r of a n a l o g r e c o r d s of t h e s t a l l p o i n t s i n d i c a t e d t h a t a l l s t a l l s w i t h t h e d i s - t o r t e d s e c t o r s t o g e t h e r i n i t i a t e d i n t h e h i g h - p r e s s u r e c o m p r e s s o r ; t h e r e f o r e f a n s t a l l p o i n t s a r e n o t i n c l u d e d o n F i g . 1 9 . Fan pump ing c a p a b i l - i t y does n o t a p p e a r t o b e a f f e c t e d b y t h e comb ined d i s t o r t i o n . (The speed l i n e shape i s s i m i l a r t o t h o s e p r o d u c e d w i t h u n i f o r m i n l e t f l o w . ) A t t e m p t s t o map t h e f a n a t 9 1 . 5 p e r c e n t speed were unsuc - c e s s f u l b e c a u s e t h e h i g h - p r e s s u r e c o m p r e s s o r was o p e r a t i n g v e r y n e a r i t s s t e a d y - s t a t e s t a l l l i m i t a t a l l e x h a u s t n o z z l e a r e a s e t t i n g s . The s t e a d y - s t a t e po in t ( F i g . 19, 9 1 . 5 p e r c e n t speed) was r e c o r d e d , a n d t h e h i g h - p r e s s u r e c o m p r e s s o r s t a l l e d b e f o r e a n y changes i n o p e r a t i n g p o i n t were a t t e m p t e d . O t h e r a t t e m p t s were made t o map t h i s speed l i n e , w i t h t h e same r e s u l t .

    The comb ined d i s t o r t i o n h a d a v e r y s e v e r e

    When t h e comb ined d i s t o r t i o n was t e s t e d w i t h t h e h i g h - t e m p e r a t u r e and l o w - p r e s s u r e r e g i o n s d i a - m e t r i c a l l y opposed , s t a l l s a t a l l speeds i n i t i a t e d i n t h e f a n i n s t e a d o f t h e h i g h - p r e s s u r e compres - s o r . T h i s r e s u l t , t h a t o p p o s e d t e m p e r a t u r e and p r e s s u r e d i s t o r t i o n s h a v e l e s s e f f e c t o n t h e s t a - b i l i t y o f a component t h a n d o d i s t o r t i o n s t h a t a r e t o g e t h e r has been documen ted i n o t h e r t e s t p r o - g r a m ~ . ~ . ~ ~ o p p o s e d t e m p e r a t u r e and p r e s s u r e d i s t o r t i o n s a r e shown i n F i g . 2 0 . The l o s s i n f a n s t a l l p r e s s u r e r a t i o w i t h t h i s comb ined d i s t o r t i o n p a t t e r n was 3 . 4 p e r c e n t a t 7 7 . 8 p e r c e n t c o r r e c t e d f a n speed, 8 . 6 p e r c e n t a t 87 .8 p e r c e n t c o r r e c t e d f a n speed, and 8 . 4 p e r c e n t a t t h e h i g h e s t c o r r e c t e d f a n speed t e s t e d . The h i g h - p r e s s u r e c o m p r e s s o r speeds c o r - r e s p o n d i n g t o t h e f a n s t a l l p o i n t s were 9 2 . 9 , 9 5 . 8 . a n d 9 8 . 8 p e r c e n t .

    The r e s u l t s o f t h e f a n mapp ing w i t h

    6

  • Summary o f R e s u l t s REFERENCES

    A PW1128 t u r b o f a n e n g i n e was t e s t e d a t a l t i - t u d e c o n d i t i o n s w i t h s t e a d y - s t a t e i n l e t t empera - t u r e d i s t o r t i o n , p r e s s u r e d i s t o r t i o n , and comb ined t e m p e r a t u r e and p r e s s u r e d i s t o r t i o n . A gaseous - f u e l e d h y d r o g e n b u r n e r l o c a t e d u p s t r e a m o f t h e e n g i n e i n l e t was u s e d t o p r o d u c e t h e c i r c u m f e r e n - t i a l and r a d i a l t e m p e r a t u r e d i s t o r t i o n p a t t e r n s . I n l e t p r e s s u r e d i s t o r t i o n was c r e a t e d w i t h a s c r e e n i n t h e i n l e t d u c t i n g . T e s t s w i t h comb ined t e m p e r a t u r e and p r e s s u r e d i s t o r t i o n i n c l u d e d v a r y - i n g t h e r e l a t i v e p o s i t i o n s o f t h e h i g h - t e m p e r a t u r e and l o w - p r e s s u r e r e g i o n s . The f o l l o w i n g r e s u l t s w e r e o b t a i n e d :

    1 . T e m p e r a t u r e d i s t o r t i o n p a t t e r n s p r o d u c e d b y t h e h y d r o g e n b u r n e r c o n s i s t e d o f t h e d e s i r e d p a t t e r n : c i r c u m f e r e n t i a l p a t t e r n s h a d l i t t l e r a d i a l c o n t e n t , and l i k e w i s e , r a d i a l p a t t e r n s had l i t t l e c i r c u m f e r e n t i a l c o n t e n t .

    2 . 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 d i s t o r t i o n r o t a t e d a p p r o x i m a t e l y 70 " i n t h e d i r e c t i o n o f ro to r r o t a t i o n as i t p a s s e d t h r o u g h t h e f a n ; and a l t h o u g h i t was a t t e n u a t e d a b o u t 15 p e r c e n t , t h e d i s t o r t i o n i n i t i a t e d a f low i n s t a b i l i t y i n t h e f a n , a s i t o p e r a t e d n e a r i t s s t e a d y - s t a t e s t a l l l i m i t , t h a t caused t h e h i g h - p r e s s u r e c o m p r e s s o r t o s t a l l j u s t b e f o r e , or n e a r t h e same t i m e a s , t h e f a n .

    3 . H u b - r a d i a l t e m p e r a t u r e d i s t o r t i o n , w h i c h was a t t e n u a t e d f r o m 4 t o 17 p e r c e n t i n p a s s i n g t h r o u g h t h e f a n , i n i t i a t e d a f low i n s t a b i l i t y i n t h e f a n w i t h r e s u l t s s i m i l a r t o t h o s e o b s e r v e d w i t h c i r c u m f e r e n t i a l i n l e t t e m p e r a t u r e d i s t o r t i o n .

    4 . T i p - r a d i a l t e m p e r a t u r e d i s t o r t i o n r e s u l t e d i n f a n s t a l l a t 8 0 . 8 a n d 9 1 . 2 p e r c e n t c o r r e c t e d f a n speed and c a u s e d s t a l l p r e s s u r e r a t i o l o s s e s o f 1 0 . 6 and 5 . 7 p e r c e n t , r e s p e c t i v e l y . A t i p - r a d i a l t e m p e r a t u r e d i s t o r t i o n a t 9 6 . 2 p e r c e n t c o r - r e c t e d f a n speed a p p e a r e d t o c a u s e h i g h - p r e s s u r e c o m p r e s s o r s t a l l . The c i r c u m f e r e n t i a l d i s t o r t i o n c o n t e n t o f t h e p a t t e r n a t 9 6 . 2 p e r c e n t speed may h a v e b e e n a c o n t r i b u t i n g f a c t o r s i n c e t h e c i r c u m - f e r e n t i a l d i s t o r t i o n i n t e n s i t y a t t h e h i g h - p r e s s u r e c o m p r e s s o r i n l e t was a b o u t d o u b l e t h a t o b s e r v e d a t t h e l o w e r speeds .

    5 . C i r c u m f e r e n t i a l i n l e t t o t a l - p r e s s u r e d i s - t o r t i o n c a u s e d t h e f a n t o s t a l l . An i n t e n s i t y o f 4 . 2 p e r c e n t c a u s e d a 6 . 2 p e r c e n t l o s s i n s t a l l p r e s s u r e r a t i o a t 90 .2 p e r c e n t c o r r e c t e d f a n speed , a n d a n i n t e n s i t y o f 7 . 2 p e r c e n t r e s u l t e d i n a n 8 . 3 p e r c e n t s t a l l p r e s s u r e r a t i o l o s s a t 100 .2 p e r c e n t c o r r e c t e d s p e e d .

    d i s t o r t i o n t o c a n c e l e a c h o t h e r ' s e f f e c t o n s t a - b i l i t y was d e m o n s t r a t e d . t h e h i g h - t e m p e r a t u r e a n d l o w - p r e s s u r e r e g i o n s t o g e t h e r caused s t a l l t o i n i t i a t e i n t h e h i g h - p r e s s u r e c o m p r e s s o r . When comb ined d i s t o r t i o n w i t h t h e h i g h - t e m p e r a t u r e and l o w - p r e s s u r e r e g i o n s o p p o s i t e each o t h e r was t e s t e d , t h e e f f e c t on h i g h - p r e s s u r e c o m p r e s s o r s t a b i l i t y was r e d u c e d t o t h e p o i n t t h a t s t a l l i n i t i a t e d i n t h e f a n .

    6 . The a b i l i t y o f p r e s s u r e a n d t e m p e r a t u r e

    Combined d i s t o r t i o n w i t h

    1 . G a b r i e l , D . , W a l l n e r , L . , L u b i c k . R . , and Vasu, G . . "Some E f f e c t s o f I n l e t P r e s s u r e a n d T e m p e r a t u r e T r a n s i e n t s on T u r b o j e t E n g i n e s .I' A e r o n a u t i c a l E n g i n e e r i n g Review, Vol. 16, No. 9 , S e p t . 1957, p p . 54-59, 6 8 .

    2 . W a l l n e r , L . E . , U s e l l e r , J.W., and S a a r i , M . J . , " A S t u d y o f T e m p e r a t u r e T r a n s i e n t s a t t h e I n l e t o f a T u r b o j e t E n g i n e , " NACA RM-E57C22, June 26, 1957 .

    M e h a l i c , C.M., "The E f f e c t o f I n l e t Temper- a t u r e a n d P r e s s u r e D i s t o r t i o n o n T u r b o j e t P e r f o r m a n c e , " AIAA P a p e r 73-1316, Nov . 1973.

    3 . B r a i t h w a i t e , W . M . , G r a b e r , E.J. J r . , and

    (NASA TM X-71431) .

    4 . M e h a l i c , C.M. and L o t t i g , R .A . , " S t e a d y - S t a t e I n l e t T e m p e r a t u r e D i s t o r t i o n E f f e c t s o n t h e S t a l l L i m i t s o f a J85-GE-13 T u r b o j e t E n g i n e , " NASA TM X-2990, 1974 .

    5 . Wenzel , L .M. , " E x p e r i m e n t a l I n v e s t i g a t i o n o f t h e E f f e c t s o f P u l s e P r e s s u r e D i s t o r t i o n s Imposed on t h e I n l e t o f a T u r b o f a n E n g i n e , " NASA TM X-1928, 1969 .

    6 . Rudey, R . A . and A n t l , R.J., "The E f f e c t o f I n l e t T e m p e r a t u r e D i s t o r t i o n o n t h e P e r f o r m -

    ' ance o f a T u r b o f a n E n g i n e Compresso r S y s t e m , " AIAA P a p e r 70-625, June 1970. (NASA TM X-53788) .

    7 . McAu lay , J .E. , " E f f e c t o f Dynamic V a r i a t i o n s i n E n g i n e I n l e t P r e s s u r e o n t h e Compresso r S y s t e m o f a Tw in -Spoo l T u r b o f a n E n g i n e , " NASA TM X-2081, 1970 .

    8 . B r a i t h w a i t e , W.M., " E x p e r i m e n t a l E v a l u a t i o n o f a TF30-P-3 T u r b o f a n E n g i n e i n a n A l t i t u d e F a c i l i t y : E f f e c t o f S t e a d y - S t a t e T e m p e r a t u r e D i s t o r t i o n , " NASA TM X-2921, 1973.

    9 . deBogdan, C . E . , D i c u s , J.H., Evans , D . G . , a n d Soeder , R.H., " E f f e c t o f a 180 -degree E x t e n t I n l e t P r e s s u r e D i s t o r t i o n on t h e I n t e r n a l F l o w C o n d i t i o n s o f a TF30-P-3 E n g i n e , " NASA TM X-3267, 1975 .

    IO. Abde lwahab , M . , " E f f e c t s o f T e m p e r a t u r e T r a n s i e n t s a t Fan I n l e t o f a T u r b o f a n E n g i n e , " NASA TP-1031, 1977.

    11 . B r a i t h w a i t e , W.M. a n d S o e d e r , R.H. , "Comb ined P r e s s u r e a n d T e m p e r a t u r e D i s t o r t i o n E f f e c t s on I n t e r n a l F l o w o f a T u r b o f a n E n g i n e , " A IAA P a p e r 79-1309, June 1979. (NASA TM-79136) .

    12 . S o e d e r , R.H. and B o b u l a . G . A . , " E f f e c t o f S t e a d y - S t a t e P r e s s u r e D i s t o r t i o n on F l o w C h a r a c t e r i s t i c s E n t e r i n g a T u r b o f a n E n g i n e , " NASA TM-79134, 1979 .

    13 . S o e d e r . R.H. a n d B o b u l a , G . A . , " E f f e c t o f S t e a d y - S t a t e T e m p e r a t u r e D i s t o r t i o n and Combined D i s t o r t i o n on I n l e t F l o w t o a T u r b o f a n E n g i n e , " NASA TM-79237, 1979 .

    7

  • 14 . Abde lwahab , M . , " E f f e c t s o f Fan I n l e t 19 . T e m p e r a t u r e D i s t u r b a n c e s o n t h e S t a b i l i t y o f a T u r b o f a n E n g i n e , " NASA TM-82699, 1981 .

    Combined P r e s s u r e and T e m p e r a t u r e D i s t o r t i o n O r i e n t a t i o n o n H i g h - 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 t a b i l i t y , " NASA TM-83771, 1984 .

    16 . Soeder , R . H . , M e h a l i c , C.M. , and S t a n c i k , K . ,

    15 . S o e d e r , R . H . and M e h a l i c , C.M. , " E f f e c t o f 20.

    " E f f e c t o f S t e a d y - S t a t e T e m p e r a t u r e 0i ; - 21 . t o r t i o n on I n l e t F l o w t o a H i g h - 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 , " NASA TM-86896, 1 9 8 5 .

    17 . B i e s i a d n y , T . J . , K l a n n , G . A . , and L i t t l e , J . K . , "Response o f a S m a l l - T u r b o s h a f t - E n g i n e

    D i s t o r t i o n , " NASA TM-83765, 1984 .

    T . J . , " T e c h n i q u e f o r I n d u c i n g C o n t r o l l e d S t e a d y - S t a t e and Dynamic I n l e t P r e s s u r e D i s t u r b a n c e s f o r J e t E n g i n e T e s t s , " NASA TM

    C o m p r e s s i o n Sys tem to I n l e t T e m p e r a t u r e 2 2 .

    18 . M e y e r , C . L . , M c A u l a y , J . E . , a n d B i e s i a d n y , 2 3 .

    X-1946, 1970 .

    Baumb ick , R.J . , " D e v i c e for P r o d u c i n g Dynamic D i s t o r t i o n P a t t e r n s a t I n l e t s o f A i r - B r e a t h i n g E n g i n e s , " NASA TM X-2026, 1970 .

    K l a n n , G . A . . B a r t h , R . L . , a n d B i e s i a d n y , T . J . , " T e m p e r a t u r e D i s t o r t i o n G e n e r a t o r f o r T u r b o - s h a f t E n g i n e T e s t i n g , " Advances i n A e r o s p a c e P r o p u l s i o n , SAE SP-594, SAE, W a r r e n d a l e , PA, 1984, p p . 89-99. (NASA TM-83748).

    Burcham, F.W. J r . , M e y e r s , L . P . , a n d Z e l l e r , J .R. , " F l l g h t E v a l u a t i o n o f M o d i f i c a t i o n s t o a D i g i t a l E l e c t r o n i c E n g i n e C o n t r o l S y s t e m i n a n F15 A i r p l a n e , " A I A A P a p e r 83 -0537 , J a n .

    "Gas T u r b i n e E n g i n e I n l e t F l o w D i s t o r t i o n G u i d e l i n e s , " SAE ARP-1420, SAE, M a r . 1978 .

    " I n l e t T o t a l - P r e s s u r e - D i s t o r t i o n C o n s i d e r - a t i o n s for Gas T u r b i n e E n g i n e s , " SAE AIR-1419, SAE, May 1983 .

    1983. (NASA TM-83088).

    TPBLE I . - CIRCUMFERENTIAL INLET TEMPERATURE DISTORTION PATTERNS H e a t e d

    a u a d r a n t s Fan i n l e t c o n d i t i o n s H i g h - p r e s s u r e

    c o m p r e s s o r speed, p e r c e n t

    c o r r e c t e d

    ~

    H i g h - p r e s s u r e c o m p r e s s c r i n l e t c o n d i t i o n s

    F a n speed, p e r c e n t

    c o r r e c t e d

    78 .9

    8 8 . 9

    99 0

    a2 7

    9 2 . 8

    81 . o 91 3

    101.9

    7 8 . 0

    aa o

    ' I 1 7

    P a t t e r n

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

    I1

    ATCITa ~ ATCiTa

    4

    4

    a

    2

    2

    2 & 3

    2 & 3

    2 & 3

    4L I

    48 I

    ' $ 1

    I 3 3

    ...

    ...

    131

    133

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    _ _ _ 181

    _..

    ...

    0 . 0 4 5 0.006 9 3 . 4

    9 6 . 0

    98 6

    9 4 . 8

    97 3

    93.8

    9 6 . 8

    9 9 . 6

    9 2 . 8

    95 4

    97 7

    118

    _..

    _..

    _ _ _ .._

    187

    I 9 6

    __.

    192

    ...

    _..

    0 . 0 3 8 0.011

    ... ...

    ,052

    042

    042

    039

    ,005

    ,004

    , 0 1 5

    ,016

    033

    ,033

    025

    '127

    ,047

    ___..

    , 0 0 9

    .....

    , 0 4 3

    .....

    aATC/T. i o t e n s I t y of c i r c t r m f e r e r i t i d l tempera tur -e d i I tort ion bATR/T. i n t e n s i t y of N'ddial t e : l i p e ' a t u l e d i s t o r t l o n

    TABLE 2 - RADIAL INLET TEMPERATURE DISTORTION PATTERNS

    H i g h - p r e s s u r e c o m p r e s s o r i n l e t 1 I c o n d i t i o n s P a t t e I n

    a M u l t i p bATCIT. C A T R / T .

    __ T i p

    T i p

    T i p

    Hub

    Hub

    Hub

    - ~. 1 514

    1 . 3 5 3

    I 791

    1 563

    ~

    0 OOR 0 030

    009 034

    007 035

    008 072

    I ..... 072 ..... 065

    i z a 1 .599 i o 7 1 . 8 4 4

    i o 6 1 . 4 3 1

    108 1 .085

    ........

    - - - - -. . -

    91 7

    93 9

    95 0

    93 3

    9 6 . 9

    99 A I I I

    - p e r - - e v o l u t i o n f a c t o r o f c l i c u m f e i - e n t i a 1 t e m p e r a t u r e d i s t o r t i o n . , t e n s i t y o f c i r c u m f e r e n t i d ! t e m p ? r a t u r e d i s t o r t l o n . i t e n s i t y of r a d i a l t e m p e r a t i l i e d i s t O i ~ t i O n

    ORfGINAE PAGB f[l. OE POOR QU-

    8

  • ORIGiNAL PAGE IS OF POOR QUALITY

    FIGURE 1. - PW1128 ENGINE INSTALLED IN ALTITUDE CHAMBER.

    9

  • ( a ) BURNER INSTALLED IN INLET PLENUM.

    (b) BURNER VIEWED LOOKING UPSTREAM. FIGURE 2. - HYDROGEN BURNER INSTALLATION.

    10 IS

    TY

  • ,-HIGH-PRESSURE TURBINE

    2 25 3

    ( a 1 ENG I NE AND INSTALLATION.

    0 STEADY-STATE TOTAL-PRESSURE PROBES. 0 STEADY-STATE STATIC-PRESSURE PROBES A STEADY-STATE TOTAL-TEMPERATURE PROBES

    SOLID SYMBOLS DENOTE HIGH RESPONSE HALF-SOLID SYMBOLS DENOTE CLOSE COUPLED

    AIRFLOW WSURING, STATION 1

    350

    80

    260

    0

    FAN INLET. STATION 2

    FAN DUCT-CWRESSOR INLET. STATION 25 CWRESSOR EXIT, STATION 3

    (b) INSTRUMENTATION LOCATIONS GIVEN I N DEGREES.

    FIGURE 3. - SCHEMATIC OF ENGINE AND INSTRUENTATION STATIONS.

    11

  • 8 PERCENT

    1.1 - 1.1 s g 3 %

    e ; 8 %

    c - 4

    % s z t" 1.0

    c-c-

    .9

    * C Y

    5 5

    $ 4 1 . 0 - u 2 9 4 - 5 E N c - +

    s 4 N

    li-

    -

    -+-c-LO

    I I I I

    0' F 3 d

    .9

    / I PERCENT 0 80 0 90.1 A 100.2 t SOLID SYMBOLS DENOTE STALL / A

    L 4 130 150 170 190 210 230 250 1

    w a , 2 K CORRECTED AIRFLOW. -, LB/SEC 62

    FIGURE 4. - FAN MAP WITH UNIFORM INLET FLOW.

    SOL I D SYMBOLS

    L , LB/SEC 'a,25H S H

    CORRECTED AIRFLOW, "25H

    FIGURE 5. - HIGH-PRESSURE COMPRESSOR MAP WITH UNIFORM INLET FLOW.

    1.1

    s c - 9 3 4

    W I- ' .9 ( a ) FAN INLET, STATION 2.

    12

  • 1 1.1

    1.1

    gk? s ?

    2 % ;s p 2

    " 2 $ 1.0

    .9

    1.1 -

    - 1.1 - gk? + ? 2 2 = 3 1.0 - % - ? - = 5 '5 g z p t"

    e ?

    .9 I I I I

    -

    I I I .9 ( a ) FAN INLET. STATION 2.

    1.1 r 1.1 r

    .9 .9 ( a ) FAN INLET. STATION 2.

    1.1 r 1.1 r

    HUB 2 0 40 60 80 T I P .9

    180 270 0 90 180 .9

    CIRCUWERENTIAL LOCATION, DEG PASSAGE HE I GHT , PERCENT

    (b) HIGH-PRESSURE COMPRESSOR INLET. STATION 25H. FIGURE 8. - TYPICAL HUB-RADIAL TEMPERATURE DISTORTION PROFILES.

    13

  • 1.1 1.1 - E: + 2 E: 3 4 e a 2 % w +" 4 ' 1.0 w I-" 4' 1.0 I - 3 + 2 2 :

    g ' I-

    t I I I .9

    FIGURE 9. - TYPICAL TIP-RADIAL TEMPERATURE DISTORTION PROFILES.

    -

    -

    I I

    0 AVERAGE OPERATING POINTS

    / (D COLD-SIDE OPERATING POINTS 0 HOT-SIDE OPERATING POINTS / --- UNIFORM INLET FLOW / FLAGGED SYMBOL DENOTES

    AVERAGE STALL POINT

    1 - 3

    W 0/ 0 ' / /. p: v) W p:

    L

    v) /d--. 00 / / .< AVERAGE ~~/fi = 91.3 PERCENT - 2

    .9

    130 150 170 190 210 230 250 1

    .

    Wa 24%

    62 CORRECTED AIRFLOW, L , LB/SEC

    FIGURE 10, - FAN OPERATING POINTS WITH 180O-EXTENT C I R - CUMFERENTIAL TEMPERATURE DISTORT ION BASED ON PARALLEL CONPRESSOR THEORY.

    1.1 1.1 - * w

    ' W E > e 4 2 s 3 s w e" 5 d u 2 % w ; 2 * e m 5 % c"

    2s 1 . 0 - 1.0 +I-

    I .9

    PERCENT - 0 78.9 0 88.9 A 99.0

    - - - I I I

    / /

    - --- UNIFORM INLET FLOW

    190 210 230 250 1 130 150 170

    wa 2 F CORRECTED AIRFLOW, -2, LB/SEC 62

    FIGURE 11. - EFFECT OF CIRCUPFERENTIAL FAN INLET TEMPERA- TURE DISTORTION ON FAN PERFORMANCE; SINGLE QUADRANT (4) HEATING (TOP), PATTERNS 1. 2. 3 .

    14

  • / *0

    0 82.7 0 92.9 0 ---

    SOLID SYMBOLS

    "

    1 130 150 170 190 210 230 250

    CORRECTED AIRFLOW, -2, Wa 2 F LB/SEC

    62

    FIGURE 12. - EFFECT OF CIRCUWERENTIAL FAN INLET TEM- PERATURE DISTORTION ON FAN PERFORMANCE : SINGLE QUAD- RANT (2) HEATING (BOTTOM). PATTERNS 4 AND 5.

    PERCENT / 0 81.1

    - 0 91.3 A 102.0

    SOLID SYMBOLS --- UNIFORM INLET FLOW / 0

    -

    -

    5 I I PERCENT /

    / 0 78.0 0 88.0 A 97.7

    SOLID SYMBOLS

    -

    -

    1 130 150 170 190 230 250

    wa 2p CORRECTED AIRFLOW. -2, LB/SEC

    62

    FIGURE 13. - EFFECT OF CIRCUWERENTIAL FAN INLET TEM- PERATURE DISTORTION ON FAN PERFORMANCE: 180' EXTENT (TOP), PATTERNS 9. 10. AND 11.

    L

    PERCENT

    0 80.8 /

    / - 0 91.2 4-

    A 96.2 0' ' UNIFORM INLET FLOW ---

    SOLID SYNB0I-S

    I'

    -

    1 130 150 170 190 210 230 250 190 210 230 250

    1 130 150 170

    w a , 2 K CORRECTED AIRFLOW, -2, Wa 2 F LB/SEC CORRECTED AIRFLOW, - , LB/SEC 62 82

    FIGURE 14. - EFFECT OF CIRCUWERENTIAL FAN INLET TEM- PERATURE DISTORTION ON FAN PERFORMANCE: 180' EXTENT (BOTTOM). PATTERNS 6. 7. AND 8.

    FIGURE 15. - EFFECT OF TIP-RADIAL INLET TEMPERATURE DISTORTION ON FAN STABILITY.

    15

  • 5 L I PERCENT 0 78.4 0 88.3 A 98.4 - --- UNIFORM INLET FLOW

    SOLID SYMBOLS A DENOTE STALL

    -

    130 150 170 190 210 230 250 1

    CORRECTED AIRFLOW. LLE, LB/SEC 62

    FIGURE 16. - EFFECT OF 360O-EXTENT HUB-RADIAL INLET TEMPERATURE DISTORTION ON FAN STABILITY.

    1.10

    1.05(

    1 .oo

    .95 W > 4 N.

    b d N.

    CL- .90

    - Q

    B 5

    1.10 er 3 v) v)

    CL

    I #

    L E -I

    1.05

    1 .oo

    .95

    5 ( a ) CORRECTED FAN SPEED = 90.2 PERCENT:

    EXTENT = 183'; AP/P = 0.092.

    0 90 180 270 360 CIRCURERENTIAL LOCATION. DEG

    ( b ) CORRECTED FAN SPEED = 100.2 PERCENT:

    .90

    EXTENT = 183'; AP/P = 0.072. FIGURE 17. - FAN INLET CIRCUEERENTIAL TOTAL

    PRESSURE DISTORTION PROFILES.

    16

  • /’ PERCENT

    0 90.2 A 100.2

    SOL I D SYMBOLS

    --- UNIFORM INLET FLOW DENOTE STALL

    0

    I’

    1 130 150 170 190 210 230 250

    CORRECTED AIRFLOW, M, LB/SEC FIGURE la. - EFFECT OF CIRCUMFERENTIAL INLET TOTAL PRES-

    62

    SURE DISTORTION ON FAN STABILITY.

    5

    $ 4 h!

    W p: 3 v) v) W PI

    - 2 L 4 LL

    5

    N.

    A P ATC PATTERN [F), - - P T FOR ATC/T PERCENT - 0 0.028 0.042 6 81.3

    io1 a / 2 A .oa5 ----- a 0 .059 .039 7 91.5

    / --- UNIFORH INLET FLOW -

    U I 1 1 130 150 170 190 210 230 250

    CORRECTED AIRFLOW, -2, Ha 2 F LB/SEC

    62 FIGURE 19. - FAN MAP WITH COMBINED PRESSURE AND TEHPER-

    ATURE DISTORTION: DISTORTIONS TOGETHER. (PATTERN NUH- BERS CORRESPOND TO TABLE 1.1

    A P ATC PATTERN A - (&), P T

    PERCENT 0 77.8 .025 ,047 9 0 87.8 .040 ---- 10 A 97.6 .073 ---- 11 --- UNIFORH INLET FLOW 1

    -

    /- SOLID SYMBOLS DENOTE STALL -

    -

    -

    1 130 150 170 190 210 230 250

    CORRECTED AIRFLOW. -2, Wa 2 F LB/SEC 62

    FIGURE 20. - EFFECT OF COMBINED DISTORTION ON FAN PERFORMANCE: DISTORTIONS OPPOSED. (PATTERN NUHBERS CORRESPOND TO TABLE 1.)

    17

  • National A e r o n a ~ l i ~ ~ and

    1 Report No

    Report Documentation Page 2. Government Accession No 3. Recipient's Catalog No

    NASA TM-100850 4. Title and Subtitle 5. Report Date

    E f f e c t o f S p a t i a l I n l e t Tempera ture and Pressu re D i s t o r t i o n on Tu rbo fan Eng ine S t a b i l i t y

    7. [email protected]) 8. Performing Organization Report No.

    C h a r l e s M . Me.hal ic

    9. Security Classif. (of this report)

    Uncl a s s i f i ed

    E-4047

    22. Price' 20. Security Classif. (of this page) 21. No of pages

    Unc l ass i f i ed 18 A02

    505-62-38 9. Performing Organization Name and Address

    11. Contract or Grant No.

    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 Lewis Research Cen te r C1 eve1 and, O h i o 441 35-31 91 13. Type of Report and Period Covered

    12. Sponsoring Agency 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 Washington, D . C . 20546-0001

    T e c h n i c a l Memorandum

    15. Supplementary Notes

    Prepared f o r t h e 2 4 t h J o i n t P r o p u l s i o n Conference cosponsored by t h e A I A A , ASEE, ASME, and S A E , Bos ton , Massachuse t t s , J u l y 11-13, 1988.

    16. Abstract

    The e f f e c t s of c i r c u m f e r e n t i a l and r a d i a l i n l e t t e m p e r a t u r e d i s t o r t i o n , c i rcum- f e r e n t i a l p r e s s u r e d i s t o r t i o n , and combined tempera tu re and p r e s s u r e d i s t o r t i o n on t h e s t a b i l i t y o f an advanced t u r b o f a n e n g i n e were i n v e s t i g a t e d e x p e r i m e n t a l l y a t s i m u l a t e d a l t i t u d e c o n d i t i o n s . W i t h c i r c u m f e r e n t i a l and r a d i a l i n l e t tempera- t u r e d i s t o r t i o n , a f low i n s t a b i l i t y g e n e r a t e d by t h e f a n o p e r a t i n g near s t a l l caused t h e h i g h - p r e s s u r e compressor t o su rge a t , or n e a r , t h e same t i m e as t h e f a n . The e f f e c t o f combined d i s t o r t i o n was dependent on t h e r e l a t i v e l o c a t i o n o f t h e h i g h - t e m p e r a t u r e and low-p ressu re r e g i o n s ; h i g h - p r e s s u r e compressor s t a l l s o c c u r r e d when t h e r e g i o n s c o i n c i d e d , and f a n s t a l l s o c c u r r e d w i t h t h e r e g i o n s Zepara ted .

    17. Key Words (Suggested by Author(s))

    Gas t u r b i n e eng ines I n l e t t e m p e r a t u r e d i s t o r t i o n

    18. Distribution Statement

    U n c l a s s i f i e d - U n l i m i t e d S u b j e c t Ca tegory 07


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