NASA T E C H N I C A L N O T E
NASA TN D-4730
2 LOA11 COPY: RETUf A FWL [WLIL-2
KIRT1A N D AFB, N
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M-1 INJECTOR DEVELOPMENT -
PHILOSOPHY AND IMPLEMENTATION
by Walter F. Dankhofi Iruing A. Johnsen, E. William Colzrad, and William A. Tomazic
Lewis Research Center Cleveland, Ohio
NATIONAL AERONAUTICS A N D SPACE A D M I N I S T R A T I O N
W AS H I N G T O N , D. C.
AUGUST 1 9 6 8
TECH LIBRARY KAFB, NM
M-1 INJECTOR DEVELOPMENT
PHILOSOPHY AND IMPLEMENTATION
By W a l t e r F. Dankhoff, Irving A. Johnsen, E. William Conrad, and William A. Tomazic Lewis Research Center Cleveland, Ohio
NATIONAL AERONAUT ICs AND SPACE ADMINISTRATION
For s a l e by the Clearinghouse for F ed e r a l Scientific and T e c h n i c a l lnformotion Springfield, V i r g i n i a 22151 CFSTl p r i c e $3.00
T h e M-1 injector design was a cooperative effort between Aerojet-General Corpora tion and Lewis R e s e a r c h Center to achieve high performance with completely stable op eration. T h e approach was based on the technology already established inthe RL-10 and 5-2 engine development programs, supplemented with the latest data obtained a t NASALewis. Scall-scale t e s t s were conducted to verify design concepts p r i o r to incorporation into the full-scale hardware. Full-scale injector testing demonstrated that the design goals were achieved.
M-1 INJECTOR DEVELOPMENT - PHILOSOPHY AND IMPLEMENTATION
by Walter F. Dankhoff,Irving A. Johnsen, E. William Conrad, and William A. Tomazic
Lewis Research Center SUMMARY
The M-1 injector was designed with the intent of circumventing the normal "cut-and try" development route by using all pertinent technology to design a satisfactory end product, that is, a n injector that combines high performance, stable operation, and dura bility. The approach employed was to make full useof all existing information and ex perience, to provide additional data (as required) through subscale testing, to employ analytical simulations t o provide guidance, and to utilize the highest level of technical competence available to a r r i v e at final design decisions. Full-scale injector testing demonstrated that the design goals were achieved. Com bustion efficiency was 96 percent atrated conditions. Vacuum specific impulse, ex trapolated from the basic test data was 429.5 pounds force second p e r pound m a s s (4212 N-sec/kg), which is equivalent to the PFRT engine specification. The injector was highly resistant to both hydraulic and acoustic instabilities. No instabilities of any s o r t were encountered at rated conditions. Low-level chugging occurred during the starttransient only. Acoustic instability was encountered only when the hydrogen inlet tem perature was dropped significantly below the engine operating value. The injector, the baffle, and the ablative chamber showed excellent integrity. Prolonged testing was pos sible without equipment repair o r replacement.
INTR0D UCT IO N
Injector development has historically been a prolonged, iterative process.The basic difficulty has been one of avoiding combustion instability, while at the s a m e time obtain ing high combustion performance. The problem has become more severe as engine size has increased. Lack of basic knowledge on instability, its prevention, and cure has gen-
erally forced injector development along the tortuous path of cut-and-try, with its associated long delays and high costs. The injector becomes the pacing item in the engine de velopment and the remainder of the program m a r k s time and accrues costs until the injector problem is solved. In some engine programs, as many as 100 full-scale injector configurations have been investigated before a satisfactory design was achieved. Although the initial efforts on the M-1 program...
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