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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

25 kW power module evolution study

This paper presents a study of evolutionary growth concepts for the 25 kW power module to augment STS mission support future capabilities. The study aimed to establish user payload requirements, define evolution methods for system initial operational capability, and formulate a development program and conceptual designs. The payload requirements analysis focused on material processing in space, public services, and solar terrestrial observations; evolutionary system concepts were evaluated to derive the power module and system support requirements, and four reference orbits were used to construct the nominal program scenario. The mission accomodations analysis evaluated the capability of the nominal program scenario and associated power module concepts to meet user needs. Finally, the recommended modular design consisting of electric power, attitude control, thermal control, and command and data handling is described, and it is concluded that the 25 kW power module is a logical first step to support the near term NASA sortie and free-flyer mission requirements.

Overall, J. W., Jr.↗
NASA NTRS1979

Engineering aspects of a thermal control subsystem for the 25 kW power module

The paper presents the key trade study results, analysis results, and the recommended thermal control approach for the 25 kW power module defined by NASA. Power conversion inefficiencies and component heat dissipation results in a minimum heat rejection requirement of 9 kW to maintain the power module equipment at desired temperature levels. Additionally, some cooling capacity should be provided for user payloads in the sortie and free-flying modes. The baseline thermal control subsystem includes a dual-loop-pumped Freon-21 coolant with the heat rejected from deployable existing orbiter radiators. Thermal analysis included an assessment of spacecraft orientations, radiator shapes and locations, and comparison of hybrid heat pipe and all liquid panels.

Schroeder, P. E.↗
NASA NTRS1979

25-kW power module

The 25-kW power module design and operational characteristics and the benefits for payloads are presented. The module will allow the Shuttle Orbiter to be utilized on-orbit to its optimum capability of power and duration for sortie/Spacelab missions, and will provide central power-rich base for free-flyer payloads requiring increased electrical power and on-orbit stay-times of up to 5 years. Concepts of the module in the sortie and free-flyer modes are depicted with resource capabilities for experimentation in astronomy, solar physics, solar terrestrial observations, and materials processing which require long duration and/or high power missions. In the sortie mode operation the Orbiter fuel cell will be in an idle mode, with the 25-kW module providing payload power needs, and in the free-flyer mode the module will provide power needs to multiple payloads. Design considerations, the thermal control subsystem, the attitude control subsystem, command and data handling, and the electrical power subsystem are described.

Powell, L. E.↗
NASA NTRS1980

A 150 and 300 kW lightweight diesel aircraft engine design study

The diesel engine was reinvestigated as an aircraft powerplant through design study conducted to arrive at engine configurations and applicable advanced technologies. Two engines are discussed, a 300 kW six-cylinder engine for twin engine general aviation aircraft and a 150 kW four-cylinder engine for single engine aircraft. Descriptions of each engine include concept drawings, a performance analysis, stress and weight data, and a cost study. This information was used to develop two airplane concepts, a six-place twin and a four-place single engine aircraft. The aircraft study consists of installation drawings, computer generated performance data, aircraft operating costs, and drawings of the resulting airplanes. The performance data show a vast improvement over current gasoline-powered aircraft.

Brouwers, A. P.↗
NASA NTRS1980

Design study: A 186 kW lightweight diesel aircraft engine

The design of an aircraft engine capable of developing 186 kW shaft power at a 7620 m altitude is described. The 186 kW design takes into account expected new developments in aircraft designs resulting in a reassessment of the power requirements at the cruise mode operation. Based on the results of this analysis a three phase technology development program is projected resulting in production dates of 1985, 1992, and 2000.

Brouwers, A. P.↗
NASA NTRS1979

Study of multi-kW solar arrays for Earth orbit applications: Midterm performance review

Planar and concentrator solar array concepts capable of providing 300 kW to 1000 kW in low Earth orbit applications in the 1987 time period at an array recurring cost less than or equal to thirty dollars per watt are examined. Silicon and gallium arsenide solar cell applicability are evaluated. On-orbit maintenance by space shuttle is also investigated. Design configurations for the solar arrays and solar cells are recommended.

Source record↗
NASA NTRS1985

Operating characteristics of a 0.87 kW-hr flywheel energy storage module

Discussion is given of the design and loss characteristics of 0.87 kW-hr (peak) flywheel energy storage module suitable for aerospace and automotive applications. The maraging steel flywheel rotor, a 46-cm- (18-in-) diameter, 58-kg (128-lb) tapered disk, delivers 0.65 kW-hr of usable energy between operating speeds of 10,000 and 20,000 rpm. The rotor is supported by 20- and 25-mm bore diameter, deep-groove ball bearings, lubricated by a self-replenishing wick type lubrication system. To reduce aerodynamic losses, the rotor housing was evacuated to vacuum levels from 40 to 200 millitorr. Dynamic rotor instabilities uncovered during testing necessitated the use of an elastometric-bearing damper to limit shaft excursions. Spindown losses from bearing, seal, and aerodynamic drag at 50 millitorr typically ranged from 64 to 193 W at 10,000 and 20,000 rpm, respectively. Discharge efficiency of the flywheel system exceeded 96 percent at torque levels greater than 21 percent of rated torque.

Loewenthal, S. H.↗
NASA NTRS1986

Testing of YUH-61A helicopter transmission in NASA Lewis 2240-kW (3000-hp facility

A helicopter transmission that was being considered for the Army's Utility Tactical Transport Attack System (UTTAS) was tested in the NASA Lewis 2240-kW (3000-hp) test facility to obtain the transmission's operational data. The results will form a vibration and efficiency data base for evaluation similar-class helicopter transmissions. The transmission's mechanical efficiency was determined to be 98.7 percent at its rated power level of 2080 kW (2792 hp). At power levels up to 113 percent of rated the transmission displayed 56 percent higher vibration acceleration levels on the right input than on the left input. Both vibration signature analysis and final visual inspection indicated that the right input spiral-bevel gear had poor contact patterns. The highest vibration meter level was 52 g's rms at the accessory gear, which had free-wheeling gearsets. At 113 percent power and 100 percent rated speed the vibration meter levels generally ranged from 3 to 25 g's rms.

Mitchell, A. M.↗
NASA NTRS1985

Development and life-testing of 10 kW class thermal arcjet engines

A facility to develop and test thermal arcjet engines over extended periods of time has been constructed and is described in this paper. It consists of a large vacuum tank, high capacity vacuum pumps, a 100 kW power supply and a large ammonia propellant storage and delivery system. The facility is instrumented to measure electrical power dissipated in the engine, propellant mass flow rate and developed thrust. Pressures and temperatures up to 2400 K can also be measured. The entire facility is computer-controlled and can be operated unattended for many weeks. Two 30 kW thermal arcjet engines that have been designed, built and are being tested in this facility are also described.

Pivirotto, T. J.↗
NASA NTRS1985

Operating characteristics of a 0.87 kW-hr flywheel energy storage module

Discussion is given of the design and loss characteristics of 0.87 kW-hr (peak) flywheel energy storage module suitable for aerospace and automotive applications. The maraging steel flywheel rotor, a 46-cm-(18-in-) diameter, 58-kg (128-lb) tapered disk, delivers 0.65 kW-hr of usable energy between operating speeds of 10,000 and 20,000 rpm. The rotor is supported by 20- and 25-mm bore diameter, deep-groove ball bearings, lubricated by a self-replenishing wick type lubrication system. To reduce aerodynamic losses, the rotor housing was evacuated to vacuum levels from 40 to 200 millitorr. Dynamic rotor instabilities uncovered during testing necessitated the use of an elastometric-bearing damper to limit shaft excursions. Spindown losses from bearing, seal, and aerodynamic drag at 50 millitorr typically ranged from 64 to 193 W at 10,000 and 20,000 rpm, respectively. Discharge efficiency of the flywheel system exceeded 96 percent at torque levels greater than 21 percent of rated torque.

Loewenthal, S. H.↗
NASA NTRS1987

Design and operation of a 100 kW subscale MPD engine

The design and operation of a subscale MPD device is described as part of a program to develop a multimegawatt engine. The device is used as a test bed for component development, primarily the cathode and anode. The first series of exploratory tests have been conducted and the engine has been operated for 8.5 hours in the steady state, over 74 runs, and at a power level as high as 72 kW. A diffuser based vacuum tank pumping scheme has been evaluated with the engine operating at 17 kW and shows a positive result.

King, D. Q.↗
NASA NTRS1987

Long duration test of a 30-kW class thermal arcjet engine

The paper describes a recent long-duration test of a 30-kW arcjet engine. This engine performed very well for 573 hours at power levels between 24 and 29 kW and with ammonia as the propellant at a mass flow rate between 0.25 and 0.27 g/s. The specific impulse varied between about 850 and 950 s and the thrust efficiency between 36 and 40 percent. The cause of final engine failure and the conditions of the electrodes and insulator are discussed in detail. An important part of this very long-term test effort was the performance and efficiency of the facility. The construction of this facility and the performance of the various critical components are discussed.

Pivirotto, T. J.↗
NASA NTRS1987

Long duration test of a 30-kW class thermal arcjet engine

This paper describes a recent long-duration test of a 30-kW arcjet engine. This engine performed very well for 573 hours at power levels between 24 and 29 kW and with ammonia as the propellant at a mass flow rate between 0.25 and 0.27 g/s. The specific impulse varied between about 850 and 950 s and the thrust efficiency between 36 and 40 percent. The cause of final engine failure and the conditions of the electrodes and insulator will be discussed in detail. An important part of this very long-term test effort was the performance and efficiency of the facility. The construction of this facility and the performance of the various critical components will also be discussed.

Pivirotto, T. J.↗
NASA NTRS1988

Internal erosion rates of a 10-kW xenon ion thruster

A 30 cm diameter divergent magnetic field ion thruster, developed for mercury operation at 2.7 kW, was modified and operated with xenon propellant at a power level of 10 kW for 567 h to evaluate thruster performance and lifetime. The major differences between this thruster and its baseline configuration were elimination of the three mercury vaporizers, use of a main discharge cathode with a larger orifice, reduction in discharge baffle diameter, and use of an ion accelerating system with larger acceleration grid holes. Grid thickness measurement uncertainties, combined with estimates of the effects of reactive residual facility background gases gave a minimum screen grid lifetime of 7000 h. Discharge cathode orifice erosion rates were measured with three different cathodes with different initial orifice diameters. Three potential problems were identified during the wear test: the upstream side of the discharge baffle eroded at an unacceptable rate; two of the main cathode tubes experienced oxidation, deformation, and failure; and the accelerator grid impingement current was more than an order of magnitude higher than that of the baseline mercury thruster. The charge exchange ion erosion was not quantified in this test. There were no measurable changes in the accelerator grid thickness or the accelerator grid hole diameters.

Rawlin, Vincent K.↗
NASA NTRS1988

Performance of 10-kW class xenon ion thrusters

Presented are performance data for laboratory and engineering model 30 cm-diameter ion thrusters operated with xenon propellant over a range of input power levels from approximately 2 to 20 kW. Also presented are preliminary performance results obtained from laboratory model 50 cm-diameter cusp- and divergent-field ion thrusters operating with both 30 cm- amd 50 cm-diameter ion optics up to a 20 kW input power. These data include values of discharge chamber propellant and power efficiencies, as well as values of specific impulse, thruster efficiency, thrust and power. The operation of the 30 cm- and 50 cm-diameter ion optics are also discussed.

Patterson, Michael J.↗
NASA NTRS1988

Detailed operating characteristics of a 30-kW ammonia arcjet engine with a contoured nozzle

Detailed experimental investigations were conducted to define the operating characteristics of a 30-kW type, arcjet engine with a contoured nozzle. The experiments were conducted in a fully instrumented facility with the engine mounted on a thrust stand. Engine performance was mapped over a power range of 10.6 to 23.0 kW with a mass flow range of 0.175 to 0.350 g/s. The data is presented in graphical form with the relationships between arc potential, arc current, power, thrust, specific impulse and thrust efficiency presented. This paper provides the first detailed accounting of arcjet operation with a contoured nozzle. Further theoretical and experimental work needs to be done to fully explain many of the features exhibited by the data.

Deininger, William D.↗
NASA NTRS1988

Internal erosion rates of a 10-kW xenon ion thruster

A 30 cm diameter divergent magnetic field ion thruster, developed for mercury operation at 2.7 kW, was modified and operated with xenon propellant at a power level of 10 kW for 567 h to evaluate thruster performance and lifetime. The major differences between this thruster and its baseline configuration were elimination of the three mercury vaporizers, use of a main discharge cathode with a larger orifice, reduction in discharge baffle diameter, and use of an ion accelerating system with larger acceleration grid holes. Grid thickness measurement uncertainties, combined with estimates of the effects of reactive residual facility background gases gave a minimum screen grid lifetime of 7000 h. Discharge cathode orifice erosion rates were measured with three different cathodes with different initial orifice diameters. Three potential problems were identified during the wear test: the upstream side of the discharge baffle eroded at an unacceptable rate; two of the main cathode tubes experienced oxidation, deformation, and failure; and the accelerator grid impingement current was more than an order of magnitude higher than that of the baseline mercury thruster. The charge exchange ion eroison was not quantified in this test. There were no measurable changes in the accelerator grid thickness or the accelerator grid hole diameters.

Rawlin, Vincent K.↗
NASA NTRS1989

Test facility and preliminary performance of a 100 kW class MPD thruster

A 260 kW magnetoplasmadynamic (MPD) thruster test facility was assembled and used to characterize thrusters at power levels up to 130 kW using argon and helium propellants. Sensitivities of discharge characteristics to arc current, mass flow rate, and applied magnetic field were investigated. A thermal efficiency correlation developed by others for low power MPD thrusters defined parametric guidelines to minimize electrode losses in MPD thrusters. Argon and helium results suggest that a parameter defined as the product of arc voltage and the square root of the mass flow rate must exceed .7 V-kg(1/2)-s(-1/2) in order to obtain thermal efficiencies in excess of 60 percent.

Sovey, James S.↗