Thermal characterization of a high thermal conductive actuator and application to variable emittance device for spacecraft

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K22407
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0301:Mechanics of materials, production engineering, design engineering, fluid engineering, thermal engineering, mechanical dynamics, robotics, aerospace engineering, marine and maritime engineering, and related fields
• Research Institution: Japan Aerospace EXploration Agency
• Principal Investigator: AKIZUKI Yuki 国立研究開発法人宇宙航空研究開発機構, 研究開発部門, 研究開発員 (00887573)
• Project Period (FY): 2020-09-11 – 2023-03-31
• Keywords: 宇宙機熱制御 / 軽量・小型 / 放射率可変 / 形状記憶合金 / ヒートパイプ / 可逆放熱デバイス

Outline of Final Research Achievements

A SMA-driven Thermal Louver (STL) was proposed and demonstrated to develop a lightweight and highly efficient thermal control device for space applications.
In the unit test of the actuator applied to STL, the heating and cooling test of the actuator combined with an SMA and arc-shaped bias springs was conducted to understand the mechanical properties of SMA when bending stress is applied, and the correlation between SMA temperature and deployment angle was obtained under several conditions. For the development and testing of the STL-BBM (heat dissipation: 50 W class), a thermal vacuum test was conducted in a simulated space environment. It was confirmed that the effective emissivity changed with the wing deployment and stowing depending on the temperature of the heat source. Comparison with a thermal analysis result showed that the heater power can be reduced.

Free Research Field

熱制御工学

Academic Significance and Societal Importance of the Research Achievements

従来の宇宙探査機に搭載されてきたサーマルルーバ等の放射率可変デバイスは質量や実効放射率のON/OFF変化量，自律動作性等の観点から，小型宇宙探査機（500kg級）への搭載は困難であり，熱設計限界が小型宇宙探査機の到達範囲を限定してきた．本研究では，形状記憶合金で可逆動作が可能な熱制御デバイス（STL）を新たに考案し，軽量・無電力ながら低温時のヒータ電力を削減可能である可能性を示すことができ，STLの適用で将来宇宙機の熱設計解を拡げることが期待される．更に，HPSMAの試作・熱輸送試験を実施し，温度に応じて形状が変化するにもかかわらず，熱伝導率が低かったSMAを高熱伝導化できる可能性を示した．