Stirling Technology Development at NASA GRC

TITLE AND SUBTITLE:
Stirling Technology Development at NASA GRC

AUTHOR(S):
Lanny G. Thieme, Jeffrey G. Schreiber, and Lee S. Mason

REPORT DATE:
January 2002

FUNDING NUMBERS:
WU-783-82-00-00
and 755-A4-14-00

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
John H. Glenn Research Center at Lewis Field
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-13119-1

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, DC 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-2001-211315-REV1

SUPPLEMENTARY NOTES:
Prepared for the Space Technology and Applications International Forum (STAIF-2002) sponsored by the American Institute of Aeronautics and Astronautics, Albuquerque, New Mexico, February 3-7, 2002. Responsible person, Lanny G. Thieme, organization code 5490, 216-433-6119.

ABSTRACT:
The Department of Energy, Stirling Technology Company (STC), and NASA Glenn Research Center (NASA Glenn) are developing a free-piston Stirling convertor for a high-efficiency Stirling Radioisotope Generator (SRG) for NASA Space Science missions. The SRG is being developed for multimission use, including providing electric power for unmanned Mars rovers and deep space missions. NASA Glenn is conducting an in-house technology project to assist in developing the convertor for space qualification and mission implementation. Recent testing of 55-We Technology Demonstration Convertors (TDC's) built by STC includes mapping of a second pair of TDC's, single TDC testing, and TDC electromagnetic interference and electromagnetic compatibility characterization on a nonmagnetic test stand. Launch environment tests of a single TDC without its pressure vessel to better understand the convertor internal structural dynamics and of dual-opposed TDC's with several engineering mounting structures with different natural frequencies have recently been completed. A preliminary life assessment has been completed for the TDC heater head, and creep testing of the IN718 material to be used for the flight convertors is underway. Long-term magnet aging tests are continuing to characterize any potential aging in the strength or demagnetization resistance of the magnets used in the linear alternator (LA). Evaluations are now beginning on key organic materials used in the LA and piston/rod surface coatings. NASA Glenn is also conducting finite element analyses for the LA, in part to look at the demagnetization margin on the permanent magnets. The world's first known integrated test of a dynamic power system with electric propulsion was achieved at NASA Glenn when a Hall-effect thruster was successfully operated with a free-piston Stirling power source. Cleveland State University is developing a multidimensional Stirling computational fluid dynamics code to significantly improve Stirling loss predictions and assist in identifying convertor areas for further improvements. This paper will update the status and results for these efforts.

SUBJECT TERMS:
Stirling engines; Nuclear electric power generation; Deep space; Mars; Roving vehicles; Random vibration; Vibration tests; Electromagnetic interference; Life (durability); Linear alternator;
Permanent magnets; Ionizing radiation

NUMBER OF PAGES:
15

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2002/TM-2001-211315-REV1.pdf
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