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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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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Fabrication and test of a space power boiler feed electromagnetic pump. 3: Endurance and final performance tests

A three-phase helical induction electromagnetic pump designed for the boiler feed pump of a potassium Rankine cycle space power system was developed and built. It was mounted in a liquid metal test loop and successfully tested over a range of potassium temperatures from 900 to 1400 F, flow rates from 0.75 to 4.85 lb/sec, developed pressures up to 340 psi, net positive suction head from 1 to 22 psi, and NaK coolant temperatures from 800 to 950 F. Maximum efficiency at design point conditions of 3.25 lb/sec flow rate, 240 psi developed head, 1000 F potassium inlet temperature, and 800 F NaK coolant inlet temperature was 16.3 percent. After the performance tests the pump was operated without any difficulty at design point for 10,000 hours, and then a limited number of repeat performance tests were made. There was no appreciable change in pump performance after 10,000 hours of operation. A supplementary series of tests using the quasi-square wave power output of a dc to three-phase ac inverter showed that the pump would operate without difficulty at a frequency as low as 25 Hz, with little loss in efficiency.

Powell, A. H.↗
NASA NTRS1969

Evaluation, construction and endurance testing of compression sealed pyrolytic boron nitride slot insulation

A high-temperature statorette, consisting of an iron-27 percent cobalt magnetic lamination stack and nickel-clad silver conductors, was tested with pyrolytic boron nitride slot insulation. Temperatures were measured in each test to determine characteristics of slot linear heat conductance from statorette conductors. Testing was carried out to temperatures of approximately 1500 F in a vacuum environment of 10-8 torr. Three assemblies were built and tested, each having a different room temperature slot clearance. The final statorette assembly was subjected to a 100-hour vacuum aging test at 1400 F followed by 25 thermal cycles. Temperature data from the three assemblies showed that decreasing slot clearance and increasing compression loading did enhance heat transfer. The temperature difference between slot and lamination at 1400 F increased 4 F during the thermal aging and an additional 10 F during the 25 thermal cycles.

Grant, W. L.↗
NASA NTRS1974

Effect of tip relief on endurance characteristics of super nitralloy and AISI M-50 spur gears

Tests were conducted with two groups of 8.89-centimeter (3.5-in.) pitch diameter spur gears with standard 20 deg involute profile with tip relief made of CVM Super-Nitralloy (5Ni-2Al) and CVM AISI M-50 at a temperature of 350 K (170 F). Super-Nitralloy gears with tip relief had a life 150 percent that of gears without tip relief. An increased scoring phenomenon was noted with the Super-Nitralloy gears with tip relief. Through-hardened AISI M-50 gears with tip relief failed due to tooth fracture. AISI M-50 gears without tip relief had a life approximately 40 times greater than the AISI M-50 gears with tip relief.

Townsend, D. P.↗
NASA NTRS1974

Combined effects of hydrazine exposure and endurance testing on solenoid-actuated valve performance

Results are presented from a test program which was conducted to assess the capability of various solenoid-actuated valve design concepts to provide performance characteristics commensurate with long-duration (ten-year) missions to explore the outer planets. The valves were installed in a hydrazine flow test setup and periodically cycled during a nine-month test period under test conditions comparable to anticipated mission operating conditions. In situ valve performance was periodically determined, and leakage was continuously monitored.

Hagler, R., Jr.↗
NASA NTRS1975

Effect of ball geometry on endurance limit in bending of drilled balls

Four designs of drilled (cylindrically hollow) balls were tested for resistance to bending fatigue. Bending fatigue has been demonstrated to be a limiting factor in previous evaluations of the drilled ball concept. A web reinforced drilled ball was most successful in resisting bending fatigue. Another design of through drilled design, involving a heavier wall than the standard reference ball, also showed significant improvement in resistance to bending fatigue.

Munson, H. E.↗
NASA NTRS1976

Inspection of two Brayton rotating units after extensive endurance testing

A system was designed to produce 2-10 kW net continuous electric power for at least 5 years. The turbine-alternator-compressor power conversion unit in the system is designated Brayton Rotating Unit (BRU). Four BRU's were fabricated and extensively tested. One BRU has accumulated 11,000 hours of operation, and another has accumulated in excess of 21,000 hours. Testing has demonstrated that the BRU's have met or exceeded performance objectives. Two BRU's were disassembled and given a thorough post-test inspection. The inspection results show that after 21,000 hours of operation there is no apparent wear or failure mode that will prevent the attainment of the 5-year life objective.

Dunn, J. H.↗
NASA NTRS1976

A 10,000 hour endurance test of a 700 series 30 cm engineering model thruster

This paper describes a 10,000 hour test of the first engineering model of the 30-cm ion thruster which is expected to form the basis of future prime propulsion systems. This test demonstrated the lifetime capability of such critical components as cathodes, vaporizers, isolators, and optics. The results of the test are described including the conclusions derived from an extensive post-test analysis of the thruster. This test did identify a major life limiting problem - discharge chamber erosion. The modifications which have been incorporated in the 900 series 30-cm ion thrusters to minimize this problem are described.

Collett, C. R.↗
NASA NTRS1978

Real-time and accelerated outdoor endurance testing of solar cells

Materials for solar-cell module construction have been studied on the basis of limited real-time outdoor exposure evaluations. The materials tested included transmission samples, sub-modules, and actual solar cells. The results suggest that glass, fluorinated ethylene propylene, and perfluoroalkoxy are good materials for the covering or encapsulation of solar-cell modules. In all cases, dirt accumulation and cleanability are important factors.

Forestieri, A. F.↗
NASA NTRS1983

Large-bore tapered-roller bearing performance and endurance to 2.4 million DN

The operating characteristics and experimental life estimates for 120.65 mm bore tapered roller bearings of two designs under combined radial and thrust loads were determined. A modified standard bearing design was tested at speeds up to 15,000 rpm. A computer optimized, high speed design was tested at speeds up to 20,000 rpm. Both designs were tested at a combined load of 26,700 N (6000 lb) radial load and and 53,400 N (12,000 lb) thrust load. Advanced helicopter transmissions which require the higher-speed capability of tapered-roller bearings also require higher temperature capability (ref. 2). Thus, materials with temperature capabilities higher than the conventional carburizing steels are required.

Parker, R. J.↗
NASA NTRS1986

Performance and endurance tests of a multipropellant resistojet for space station auxiliary propulsion

This paper presents the results of an effort to demonstrate the technology readiness of a long-life multipropellant resistojet for space station auxiliary propulsion. Experiments were performed to evaluate the compatibility of grain-stabilized platinum tubes at temperatures up to 1400 deg C in environments of CO2, CH4, NH3, H2O, and H2. All samples tested showed extrapolated lifetimes in excess of 10,000 hr based on 10 percent mass loss as end-of-life. However, samples tested in an ammonia atmosphere at 1400 deg C showed severe pitting, which raised concerns about the compatibility of grain-stabilized platinum with ammonia-containing atmospheres. Additional tests showed that reducing the metal temperature to about 900 deg C (+ or - 100 deg C) significantly reduced this adverse effect.

Morren, W. E.↗