A comprehensive analytical and experimental program that resulted in an advanced computerized analysis for predicting the performance of a fluorine-hydrogen Main Tank Injection (MTI) pressurization system for LH 2 -fueled space vehicles is described. Accuracy of the analysis was verified by a series of 17 tests of a fullscale MTI pressure control system in a 1000 ft 3 flight-weight LH 2 tank. Prepressurization, constant-pressure hold, and LH 2 expulsion at controlled tank pressure were demonstrated over a wide range of ullage volumes, pressures, flowrates, and injector configurations, with reasonable ullage gas and tank-wall temperature and efficient fluorine usage. Nomenclature a C d f fm = T -U = W = X = A P Subscripts b C F,F 2 = 9 = H 2 ,HF = J = m -M = mix = P = r = u = o =

T h i s r e p o r t w a s p r e p a r e d by McDonnell Douglas A s t r o n a u t i c s C-ompany under C o n t r a c t NAS3-14381.National A e r o n a u t i c s and Space Adm.inistration, Lewis R e s e a r c h C e n t e r , C h e m i c a l and N u c l e a r Rocket P r o c u r e m e n t Section, Cleveland, Ohio.The NASA P r o j e c t Manager f o r the c o n t r a c t is Mr. E r w i n A. Edelman. This is the final r e p o r t on the c o n t r a c t , and i t s u m m a r i z e s the t e c h n i c a l e f f o r t f r o m 1 J u l y 1971 to 31 J a n u a r y 1972.The c o n t r a c t is a d m i n i s t e r e d by the ... I l l ABST RA CTA c o m p r e h e n s i v e analytical and e x p e r i m e n t a l p r o g r a m w a s p e r f o r m e d to evaluate the p e r f o r m a n c e of a unique fluorine-hydrogen j e t -p u m p i n j e c t o r f o r m a i n tank injection (MTI) p r e s s u r i z a t i o n of a liquid hydrogen ( L H 2 ) tank. LH i n j e c t o r and MTI p r e s s u r e c o n t r o l s y s t e m i n a 2 8 . 3 m flight-weight LH tank. Although the i n j e c t o r did not effectively j e tpump LH continuously, it showed improved p r e s s u r i z a t i o n p e r f o r m a n c e c o m p a r e d to s t r a i g h t -p i p e i n j e c t o r s t e s t e d u n d e r the s a m e conditions in a p r e v i o u s p r o g r a m . p e r f o r m a n c e p r e d i c t i o n f o r the j e t -p u m p injector.The i n j e c t o r p e r f o r m a n c e d u r i n g p r e s s u r i z a t i o n and expulsion w a s d e t e r m i n e d by a s e r i e s of s e v e n t e s t s of a f u l l -s c a l e 3 3 2( 1 , 000 ft ) r e s u l t a n t hot hydrogen a t 1555°K (2800"R) i s used to p r e s s u r i z e the LH2 tank.(1, 000-ft ) flightweight LH NAS3-13306 to evaluate s t r a i g h t -p i p e and diffuser-type MTI i n j e c t o r s . Seven t e s t s w e r e p e r f o r m e d a t v a r i e d L Hullage v o l u m e s f r o m 3 m3 (106 f t ) t o 26. 9 m s u r i z a t i o n , c o n s t a n t -p r e s s u r e hold, and L H expulsion a t controlled 2 tank p r e s s u r e s of 30 x l o 4 N / m w e r e d e m o n s t r a t e d . The i n j e c t o r second s t a g e L H pumping annulus w a s d a m a g e d by overheating c a u s e d by i t s inability to pump LH2 with l a r g e initial u l l a g e s and with cyclic operation. N e v e r t h e l e s s , the i n j e c t o r d e m o n s t r a t e d i m p r o v e d p r e s s u r i z a t i o n p e r f o r m a n c e ( l e s s GH i n j e c t o r s t e s t e d previously.indicated t h a t the p e r f o r m a n c e gain w a s due to f i r s t s t a g e G F and second s t a g e GH t r a t i o n and u l l a g e mixing.code t o allow j e t -p u m p i n j e c t o r p e r f o r m a n c e p r e d i c t i o n . pumping which gave g r e a t e r injectant j e t p e n e -2Modifications w e r e made t o the M T I c o m p u t e r v i i CONTENTS

T h i s r e p o r t w a s p r e p a r e d by McDonnell Douglas A s t r o n a u t i c s C-ompany under C o n t r a c t NAS3-14381.National A e r o n a u t i c s and Space Adm.inistration, Lewis R e s e a r c h C e n t e r , C h e m i c a l and N u c l e a r Rocket P r o c u r e m e n t Section, Cleveland, Ohio.The NASA P r o j e c t Manager f o r the c o n t r a c t is Mr. E r w i n A. Edelman. This is the final r e p o r t on the c o n t r a c t , and i t s u m m a r i z e s the t e c h n i c a l e f f o r t f r o m 1 J u l y 1971 to 31 J a n u a r y 1972.The c o n t r a c t is a d m i n i s t e r e d by the ... I l l ABST RA CTA c o m p r e h e n s i v e analytical and e x p e r i m e n t a l p r o g r a m w a s p e r f o r m e d to evaluate the p e r f o r m a n c e of a unique fluorine-hydrogen j e t -p u m p i n j e c t o r f o r m a i n tank injection (MTI) p r e s s u r i z a t i o n of a liquid hydrogen ( L H 2 ) tank. LH i n j e c t o r and MTI p r e s s u r e c o n t r o l s y s t e m i n a 2 8 . 3 m flight-weight LH tank. Although the i n j e c t o r did not effectively j e tpump LH continuously, it showed improved p r e s s u r i z a t i o n p e r f o r m a n c e c o m p a r e d to s t r a i g h t -p i p e i n j e c t o r s t e s t e d u n d e r the s a m e conditions in a p r e v i o u s p r o g r a m . p e r f o r m a n c e p r e d i c t i o n f o r the j e t -p u m p injector.The i n j e c t o r p e r f o r m a n c e d u r i n g p r e s s u r i z a t i o n and expulsion w a s d e t e r m i n e d by a s e r i e s of s e v e n t e s t s of a f u l l -s c a l e 3 3 2( 1 , 000 ft ) r e s u l t a n t hot hydrogen a t 1555°K (2800"R) i s used to p r e s s u r i z e the LH2 tank.(1, 000-ft ) flightweight LH NAS3-13306 to evaluate s t r a i g h t -p i p e and diffuser-type MTI i n j e c t o r s . Seven t e s t s w e r e p e r f o r m e d a t v a r i e d L Hullage v o l u m e s f r o m 3 m3 (106 f t ) t o 26. 9 m s u r i z a t i o n , c o n s t a n t -p r e s s u r e hold, and L H expulsion a t controlled 2 tank p r e s s u r e s of 30 x l o 4 N / m w e r e d e m o n s t r a t e d . The i n j e c t o r second s t a g e L H pumping annulus w a s d a m a g e d by overheating c a u s e d by i t s inability to pump LH2 with l a r g e initial u l l a g e s and with cyclic operation. N e v e r t h e l e s s , the i n j e c t o r d e m o n s t r a t e d i m p r o v e d p r e s s u r i z a t i o n p e r f o r m a n c e ( l e s s GH i n j e c t o r s t e s t e d previously.indicated t h a t the p e r f o r m a n c e gain w a s due to f i r s t s t a g e G F and second s t a g e GH t r a t i o n and u l l a g e mixing.code t o allow j e t -p u m p i n j e c t o r p e r f o r m a n c e p r e d i c t i o n . pumping which gave g r e a t e r injectant j e t p e n e -2Modifications w e r e made t o the M T I c o m p u t e r v i i CONTENTS

ENGINEERING NOTES are short manuscripts describing new developments or important results of a preliminary nature. These Notes cannot exceed 6 manuscript pages and 3 figures; a page of text may be substituted for a figure and vice versa. After informal review by the editors, they may be published within a few months of the date of receipt. Style requirements are the same as for regular contributions (see inside back cover). a d T u x y z P Nomenclature = acceleration = jet exit diameter = gas temperature = velocity = axial distance downward from pressurant injector = momentum diameter = gas compressibility factor = density Subscripts b,m,u = buoyancy, mixing and ullage, respectively0