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Active Vibration Reduction of the Advanced Stirling ConvertorStirling Radioisotope Power Systems (RPS) are being developed as an option to provide power on future space science missions where robotic spacecraft will orbit, flyby, land or rove. A Stirling Radioisotope Generator (SRG) could offer space missions a more efficient power system that uses one fourth of the nuclear fuel and decreases the thermal footprint compared to the current state of the art. The Stirling Cycle Technology Development (SCTD) Project is funded by the RPS Program to developing Stirling-based subsystems, including convertors and controller maturation efforts that have resulted in high fidelity hardware like the Advanced Stirling Radioisotope Generator (ASRG), Advanced Stirling Convertor (ASC), and ASC Controller Unit (ACU). The SCTD Project also performs research to develop less mature technologies with a wide variety of objectives, including increasing temperature capability to enable new environments, improving system reliability or fault tolerance, reducing mass or size, and developing advanced concepts that are mission enabling. Active vibration reduction systems (AVRS), or "balancers", have historically been developed and characterized to provide fault tolerance for generator designs that incorporate dual-opposed Stirling convertors or enable single convertor, or small RPS, missions. Balancers reduce the dynamic disturbance forces created by the power piston and displacer internal moving components of a single operating convertor to meet spacecraft requirements for induced disturbance force. To improve fault tolerance for dual-opposed configurations and enable single convertor configurations, a breadboard AVRS was implemented on the Advanced Stirling Convertor (ASC). The AVRS included a linear motor, a motor mount, and a closed-loop controller able to balance out the transmitted peak dynamic disturbance using acceleration feedback. Test objectives included quantifying power and mass penalty and reduction in transmitted force over a range of ASC operating parameters and mounting conditions. All tests were performed at three different piston amplitudes, 3.0, 3.75, and 4.5 mm. Overall, the transmitted force was reduced to 2 percent of the total unbalanced force by actively balancing out only the first fundamental frequency, with balancer motor power remaining under 1 watt. The test results will be used to guide future balancer designs.
Document ID
20160014702
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Wilson, Scott D.
(NASA Glenn Research Center Cleveland, OH United States)
Metscher, Jonathan F.
(NASA Glenn Research Center Cleveland, OH United States)
Schifer, Nicholas A.
(NASA Glenn Research Center Cleveland, OH United States)
Date Acquired
December 19, 2016
Publication Date
December 1, 2016
Subject Category
Engineering (General)
Report/Patent Number
GRC-E-DAA-TN35187
E-19313
AIAA Paper 2016-5015
NASA/TM-2016-219416
Meeting Information
Meeting: International Energy Conversion Engineering Conference (IECEC)
Location: Salt Lake City, UT
Country: United States
Start Date: July 25, 2016
End Date: July 27, 2016
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS 138494.04.18.01.01.01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
Balancer
Active Vibration Reduction
Stirling Radioisotope Power
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