SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 6 - March 24, 2006

20 SPACECRAFT PROPULSION AND POWER
Includes main propulsion systems and components, e.g., rocket engines; and spacecraft auxiliary power sources.

For related information see also 07 Aircraft Propulsion and Power, 28 Propellants and Fuels, 15 Launch Vehicles and Launch Operations, and 44 Energy Production and Conversion.

20060009455 NASA Marshall Space Flight Center, Huntsville, AL, USA

Closed Cycle Magnetohydrodynamic Nuclear Space Power Generation Using Helium/Xenon Working Plasma

Litchford, R. J.; Harada, N.; September 2005; 40 pp.; In English Report No.(s): NASA/TP-2005-214187; M-1149; Copyright; Avail.: CASI: A03, Hardcopy

A multimegawatt-class nuclear fission powered closed cycle magnetohydrodynamic space power plant using a helium/xenon working gas has been studied, to include a comprehensive system analysis. Total plant efficiency was expected to be 55.2 percent including pre-ionization power. The effects of compressor stage number, regenerator efficiency, and radiation cooler temperature on plant efficiency were investigated. The specific mass of the power generation plant was also examined. System specific mass was estimated to be 3 kg/kWe for a net electrical output power of 1 MWe, 2-3 kg/kWe at 2 MWe, and approx.2 kg/KWe at \g3 MWe. Three phases of research and development plan were proposed: (1) Phase I-proof of principle, (2) Phase II-demonstration of power generation, and (3) Phase III-prototypical closed loop test. Author

Nuclear Electric Power Generation; Electric Power Plants; Magnetohydrodynamic Generators; Nuclear Fission; Systems Analysis; Regenerators; Feedback Control; Compressor Efficiency

20060009471 NASA Glenn Research Center, Cleveland, OH, USA

Carbon-Carbon Recuperators in Closed-Brayton-Cycle Space Power Systems

Barrett, Michael J.; Johnson, Paul K.; Naples, Andrew G.; February 2006; 16 pp.; In English; Second International Energy Conversion Engineering Conference, 16-19 Aug. 2004, Providence, RI, USA Contract(s)/Grant(s): 22-973-80-10 Report No.(s): NASA/TM-2006-213302; E-14749; AIAA Paper 2004-5652; Copyright; Avail.: CASI: A03, Hardcopy

The feasibility of using carbon-carbon (C-C) recuperators in conceptual closed-Brayton-cycle space power conversion systems was assessed. Recuperator performance expectations were forecast based on notional thermodynamic cycle state values for potential planetary missions. Resulting thermal performance, mass and volume for plate-fin C-C recuperators were estimated and quantitatively compared with values for conventional offset-strip-fin metallic designs. Mass savings of 30 to 60 percent were projected for C-C recuperators with effectiveness greater than 0.9 and thermal loads from 25 to 1400 kWt. The smaller thermal loads corresponded with lower mass savings; however, 60 percent savings were forecast for all loads above 300 kWt. System-related material challenges and compatibility issues were also discussed. Author

Brayton Cycle; Closed Cycles; Nuclear Electric Power Generation; Thermodynamic Cycles; Temperature Effects; Spacecraft Power Supplies; Satellite Solar Energy Conversion; Regenerators

20060009491 NASA Glenn Research Center, Cleveland, OH, USA

Extended Operation of Stirling Convertors in a Thermal Vacuum Environment

Oriti, Salvatore M.; February 2006; 14 pp.; In English; Third International Energy Conversion Engineering Conference, 15-18 Aug. 2005, San Francisco, CA, USA; Original contains color illustrations Contract(s)/Grant(s): WBS 972-20-01 Report No.(s): NASA/TM-2006-213984; AIAA Paper 2005-5747; E-15306; No Copyright; Avail.: CASI: A03, Hardcopy

A 110 watt Stirling Radioisotope Generator (SRG110) is being developed for potential use on future NASA exploration missions. The development effort is being performed by Lockheed Martin under contract to the Department of Energy (DOE). Infinia, Corp. supplies the free-piston Stirling power convertors, and NASA Glenn Research Center (GRC) provides support to the effort in a range of technologies. This generator features higher efficiency and specific power compared to alternatives. One potential application for the generator would entail significant cruise time in the vacuum of deep space. A test has been initiated at GRC to demonstrate functionality of the Stirling convertors in a thermal vacuum environment. The test article resembles the configuration of the SRG110, however the requirement for low mass was not considered. This test demonstrates the operation of the Stirling convertors in the thermal vacuum environment, simulating deep space, over an extended period of operation. The status of the test as well as the data gathered will be presented in this paper. Author

Stirling Cycle; Thermal Environments; Vacuum

20060009996 Texas Univ., Austin, TX, USA

Railplug Ignition System for Enhanced Engine Performance and Reduced Maintenance. (Final Report, September 30, 2001-December 31, 2004)

Ezekoye, D. K.; Hall, M.; Matthews, R.; January 2005; 134 pp.; In English Report No.(s): DE2005-860176; No Copyright; Avail.: National Technical Information Service (NTIS)

This Final Technical Report discusses the progress that was made on the experimental and numerical tasks over the duration of this project. The primary objectives of the project were to (1) develop an improved understanding of the spark ignition process, and (2) develop the railplug as an improved ignitor for large bore stationary natural gas engines. We performed fundamental experiments on the physical processes occurring during spark ignition and used the results from these experiments to aid our development of the most complete model of the spark ignition process ever devised. The elements in this model include 1) the dynamic response of the ignition circuit, 2) a chemical kinetics mechanism that is suitable for the reactions that occur in the plasma, 3) conventional flame propagation kinetics, and 4) a multi-dimensional formulation so that bulk flow through the spark gap can be incorporated. Fundamental experiments, engine experiments, and modeling tasks were used to help develop the railplug as a new ignitor for large bore natural gas engines. NTIS

Ignition Systems; Maintenance

Source: NASA