Characterization of the Advanced Stirling Radioisotope Generator EU2

Lewandowski, Edward J.; Oriti, Salvatore M.; Schifer, Nicholas A.

doi:10.2514/6.2015-3808

Cited by 9 publications

(6 citation statements)

References 5 publications

(8 reference statements)

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“…The Stirling Cycle Technology Development Project (SCTD) is funded by the RPS Program to develop Stirling-based subsystems, including convertors and controller American Institute of Aeronautics and Astronautics maturation efforts that have resulted in high fidelity hardware like the ASRG, ASC, and ACU. 1,2 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. 3 The development of the new linear alternator concepts discussed in this paper is focused on improving system reliability and reducing mass.…”

Section: Introductionmentioning

confidence: 99%

Development of a Low Inductance Linear Alternator for Stirling Power Convertors

Geng

Schifer²

2017

15th International Energy Conversion Engineering Conference

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Section: Introductionmentioning

confidence: 99%

Development of a Low Inductance Linear Alternator for Stirling Power Convertors

Geng

Schifer²

2017

15th International Energy Conversion Engineering Conference

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“…The test results were as expected, and the generator demonstrated it would achieve over 28.6% efficiency (DC output power / gross heat input) in a deep space vacuum environment with a 4 K sink temperature. 2 However, power fluctuations started to occur on both convertors shortly after EU2 testing began and after the convertors had operated for over 3,400 hours. Over time, the power fluctuations became more frequent on both approaches the vacuum of space, improving effectiveness of the insulation that surrounds the heat source.…”

Section: Introductionmentioning

confidence: 99%

“…Project Lead Engineer, Thermal Energy Conversion Branch, 21000 Brookpark Rd., AIAA Senior Member 2. Lead System Engineer, 3000 Aerospace Parkway 3 Mechanical Engineer, Thermal Energy Conversion Branch, 21000 Brookpark Rd.…”

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confidence: 99%

Advanced Stirling Radioisotope Generator EU2 Anomaly Investigation

Lewandowski¹,

Oriti²

2016

14th International Energy Conversion Engineering Conference

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The Advanced Stirling Radioisotope Generator (ASRG) Engineering Unit 2 (EU2) is the highest fidelity electrically-heated Stirling radioisotope generator built to date. NASA Glenn Research Center (GRC) completed the assembly of the ASRG EU2 in September, 2014 using hardware from the now cancelled ASRG flight development project. The ASRG EU2 integrated the first pair of Sunpower's ASC-E3 Stirling convertors (ASC-E3 #1 and #2) in an aluminum generator housing with Lockheed Martin's Engineering Development Unit (EDU) 4 controller. After just 179 hours of EU2 generator operation, the first power fluctuation occurred on ASC-E3 #1. The first power fluctuation occurred 175 hours later on ASC-E3 #2. Over time, the power fluctuations became more frequent on both convertors and larger in magnitude. Eventually the EU2 was shut down in January, 2015. An anomaly investigation was chartered to determine root cause of the power fluctuations and other anomalous observations. A team with members from GRC, Sunpower, and Lockheed Martin conducted a thorough investigation of the EU2 anomalies. Findings from the EU2 disassembly identified proximate causes of the anomalous observations. Discussion of the team's assessment of the primary possible failure theories, root cause, and conclusions is provided. Recommendations are made for future Stirling generator development to address the findings from the anomaly investigation. Additional findings from the investigation are also discussed.convertors and larger in magnitude, up to 9.4 W. Early power fluctuations were less than 2 seconds in duration, while later drops in power lasted for hours. Eventually the EU2 was shut down in January, 2015.Given the flight-like fidelity of the EU2 hardware, with the ASC-E3 convertors and the EDU 4 controller, and the flight-like rigor that had been used to assemble the generator housing assembly (GHA), such an early failure was both unexpected and disconcerting. The EU2 was intended to be part of a broader program to establish a reliability database for future Stirling-based power systems, 3 but this failure was a setback to that initiative. An anomaly investigation was chartered to determine root cause of the power fluctuations, to the extent possible, so as to learn from this event and then apply insights gained to future dynamic power conversion systems. The EU2 anomaly investigation team included members from GRC, Sunpower, and LM. Various GRC technology experts were brought in as needed to support different phases of the investigation.This paper chronicles the EU2 anomaly investigation process that took place in 2015. Findings from the disassembly and inspection of the GHA and ASC-E3 convertors are discussed, along with the proximate cause of the power fluctuations. Extensive analysis, modeling, and follow-on testing was conducted, leading to possible failure theories and an assessment of likely root cause and conclusions. Recommendations are provided for future Stirling generator development. A. The ASRG EU2This section provides the reader with a ...

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“…The test results provides a basic understanding of EU2 characteristics that can be evaluated relative to system requirements and predictions. 4 Prior to integration into higher level system tests, convertors are tested to enable independent performance verification, provide a way to simulate the life cycle of a flight convertor within certain limits, and mitigate risk by providing the life certification plan with input data. To start, each completed ASC convertor undergoes Final Performance Testing at the vendor before entering the hardware acceptance review.…”

Section: Introductionmentioning

confidence: 99%

Overview of Stirling Technology Research at NASA Glenn Research Center

Wilson

Schifer²,

Williams³

et al. 2015

13th International Energy Conversion Engineering Conference

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Stirling Radioisotope Power Systems (RPS) are under development to provide power on future space science missions where robotic spacecraft will orbit, flyby, land or rove using less than a quarter of the plutonium the currently available RPS uses to produce about the same power. Glenn Research Center's (GRC's) newly formulated Stirling Cycle Technology Development Project (SCTDP) continues development of Stirling-based systems and subsystems, which include a flight-like generator and related housing assembly, controller, and convertors. The project also develops less mature technologies under Stirling Technology Research, with a focus on demonstration in representative environments to increase the technology readiness level (TRL). Matured technologies are evaluated for selection in future generator designs. Stirling Technology Research tasks focus on a wide variety of objectives, including increasing temperature capability to enable new environments, reducing generator mass and/or size, improving reliability or system fault tolerance, and developing alternative designs. The task objectives and status are summarized.

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Characterization of the Advanced Stirling Radioisotope Generator EU2

Cited by 9 publications

References 5 publications

Development of a Low Inductance Linear Alternator for Stirling Power Convertors

Development of a Low Inductance Linear Alternator for Stirling Power Convertors

Advanced Stirling Radioisotope Generator EU2 Anomaly Investigation

Overview of Stirling Technology Research at NASA Glenn Research Center

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