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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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The performance and operating problems of a small hot-gas generator burning liquid hydrogen with liquid oxygen are presented. Two methods of ignition are discussed. Injector and combustion chamber design details based on rocket design criteria are also given. A carefully fabricated showerhead injector of simple design provided a gas generator that yielded combustion efficiencies of 93 and 96 percent.
A damage tolerance assessment was conducted of an 8,000 gallon pressurized Liquid Oxygen (LOX) tank. The LOX tank is constructed of a stainless steel pressure vessel enclosed by a thermal-insulating vacuum jacket. The vessel is pressurized to 2,250 psi with gaseous nitrogen resulting in both thermal and pressure stresses on the tank wall. Finite element analyses were performed on the tank to characterize the stresses from operation. Engineering material data was found from both the construction of the tank and the technical literature. An initial damage state was assumed based on records of a nondestructive inspection performed on the tank. The damage tolerance analyses were conducted using the NASGRO computer code. This paper contains the assumptions, and justifications, made for the input parameters to the damage tolerance analyses and the results of the damage tolerance analyses with a discussion on the operational safety of the LOX tank.
Chamber pressure variations and rocket combustor performance for gaseous hydrogen-liquid oxygen propellant system
Shrouded turbine bucket natural frequencies and associated resonant shaft speeds for M-1 liquid oxygen turbopump
Vulcanizable elastomers for use with liquid oxygen
Reactivity of launch vehicle organic materials with liquid oxygen
This paper presents a method for determining the surface temperature of liquid-oxygen turbopump bearings during the operation of the turbopump. The method relies on the fact that the surface temperature of a bearing can be correlated with the composition of oxides used to cover the bearings, using oxidation samples for calibration and AES for chemical analysis. Using this method, it was found that, for the bearings studied, the maximum temperature reached by stainless steel bearings was 600 C, which is well below the 1100-C autoignition temperature of the AISI stainless steel.
Compressibility and sealing properties of laminated composite-fluorocarbon polymer cryogenic gaskets compatible with liquid oxygen
Equations and tables are presented for the viscosity and thermal conductivity coefficients of gaseous and liquid oxygen at temperatures between 80 K and 400 K for pressures up to 200 atm. and at temperatures between 80 K and 2000 K for the dilute gas. A description of the anomalous behavior of the thermal conductivity in the critical region is included. The tabulated coefficients are reliable to within about 15% except for a region in the immediate vicinity of the critical point. Some possibilities for future improvements of this reliability are discussed.
Extensive flow rate, pressure, and temperature data available for validating computer models of liquid-oxygen transfer systems. Data on "waterhammer" pressure spikes included.
Ball bearings with glass fiber reinforced Teflon ball retainers from hot-fired liquid oxygen turbopumps were analyzed by X-ray photoelectron spectroscopy to determine the extent of Teflon transfer and/or chemical reaction at the bearing surface. No Teflon, but metal fluorides could be found on the metal surface. This indicates that Teflon decomposes and reacts with the bearing steel to form fluorides. Hence, Teflon does not appear to function directly as a lubricant under these operating conditions.
Wear and friction of mechanical carbons sliding against metal surfaces in liquid oxygen to determine their lubrication potential
Structural adhesives prepared from fluorinated polyurethanes for use with liquid oxygen
Analyses and predicted performance of a 50-mm diameter, spiral-groove face seal to seal liquid oxygen at 5.17 MPa pressure, and operating at surface speeds of 183 m/s are described. The pressure-balanced spiral-groove concept is introduced that circulates spiral-groove flow independent of leakage flow. Independent flow paths preclude overheating from vaporization and consequent flow blockage. The analysis accounts for fluid turbulence and inertia, thermoelastic distortions, and dynamic response. An operating-range map was developed as a function of speed and pressure. The fluid-film analysis is summarized in the Appendix.
The coil spring in a Space Shuttle liquid oxygen check valve failed due to cyclic fatigue in September, 1991. The dual-flapper, swing check valve is used to prevent reverse flow to the Space Shuttle Main Engines. Upon inspection of the failed component, the spring tangs were found to be missing and heavy wear was observed on the inner diameter of the spring coils. The fracture surfaces revealed that the metal had been steadily worn away until a simple overload caused the final fracture. A series of flow tests using water and a water/gas mixture was conducted to identify the flow phenomenon which produced the cyclic wear. A Plexiglas outlet housing was utilized to view the flapper behavior under different flow conditions and to aid in high speed photography. The tests revealed that flow instabilities induced two oscillatory flapper responses: a rocking mode and a chattering mode. Initially, attempts were made to reduce the spring-flapper oscillations. However, the final solution to the problem was a springless configuration which satisfied the valve's design requirements and eliminated the oscillations. The springless design relied on the inherent ability of the reverse flow momentum to close the flappers.
The performance of jet fuel with an oxidant mixture containing 70 percent liquid fluorine and 30 percent liquid oxygen by weight was investigated in a 500-pound-thrust engine operating at a chamber pressure of 300 pounds per square inch absolute. A one-oxidant-on-one-fuel skewed-hole impinging-jet injector was evaluated in a chamber of characteristic length equal to 50 inches. A maximum experimental specific impulse of 268 pound-seconds per pound was obtained at 25 percent fuel, which corresponds to 96 percent of the maximum theoretical specific impulse based on frozen composition expansion. The maximum characteristic velocity obtained was 6050 feet per second at 23 percent fuel, or 94 percent of the theoretical maximum. The average thrust coefficient was 1.38 for the 500-pound thrust combustion-chamber nozzle used, which was 99 percent of the theoretical (frozen) maximum. Mixtures of fluorine and oxygen were found to be self-igniting with jet fuel with fluorine concentrations as low as 4 percent, when low starting propellant flow rated were used.
Annotated bibliography of vulcanicable elastomers for use with liquid oxygen
The larger of two ball bearings used to support the rotor of the low pressure liquid oxygen turbopump in each of the shuttle main engines was analyzed to identify the cause of severe internal wear. The actual operating loads were calculated along with their direction and length of time at each load based on the size and location of the race contact paths. It is suggested that the engine component design be modified to reduce bearing stress and enhance lubrication.