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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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Intelligent Long Endurance Observing System (ILEOS)
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Intelligent Long Endurance Observing System (ILEOS)
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Intelligent Long Endurance Observing System (ILEOS)
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THIRTY DAY ENDURANCE TEST OF A 30KW ARC JET ENGINE
Details are presented on a 30-day run of a radiation cooled thermal arc jet engine. The engine performed satisfactorily throughout the test period, maintaining a thrust of 250 grams and a propellant specific impulse greater than 1000 seconds a t an input power level of 30 kilowatts. The resulting propulsive efficiency was greater than 40 percent. Visual examination of the arc discharge through a quartz constrictor indicates that there is a smooth, constant diameter, bright core extending from the cathode completely through the constrictor to the cathode. Photographic observations on the arc discharge, using a red filter, indicate that the center of the column is darker than the outside: and this, in turn, suggests that the maximum core temperature is greater than 20,000°K. Calculations on the energy flow rate through a fully developed laminar column, combined with the experimental observation that the longitudinal energy flux gradient along the column is small, suggest that there may be a region of high volumetric energy release in the vicinity of the cathode tip.
THIRTY DAY ENDURANCE TEST OF A 30KW ARC JET ENGINE
Observations on the energy transfer processes occurring within the arc jet engine
Bearing-lubricant endurance characteristics at high speeds and high temperatures Final report, 1 Sep. 1962 - 31 Aug. 1965
Failure mode and operation life of ball bearings using fluid lubricants at high temperatures in recirculating system
Voltage endurance tests for closed-cell foams
High voltage strength of polyurethane plastic foams for encapsulant applications
Development and endurance testing of high- temperature ceramic voltage-regulator tubes
Long-term performance tests of neon gas filled, high-temperature ceramic voltage-regulator tubes
Automated endurance testing of a Brayton power conversion system
Computer controlled durability test of 50,000 hour life Brayton power conversion system for space applications
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.
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.
An earlier generation of long-enduring south temperate ovals on Jupiter.
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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.
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.
High-performance Schottky diodes endure high temperatures
Fabrication process and aluminum/GaAs (gallium arsenide) coupling are used to produce Schottky diodes that have high cutoff frequencies and can withstand operating temperatures in excess of 500 C.
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.
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.