2020 Fiscal Year Final Research Report

Understanding the interaction with fluids and granular materials in microgravity environment

Research Project

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Project/Area Number	18KK0108
Research Category	Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))
Allocation Type	Multi-year Fund
Review Section	Medium-sized Section 20:Mechanical dynamics, robotics, and related fields
Research Institution	Japan Aerospace EXploration Agency
Principal Investigator	Otsuki Masatsugu 国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 准教授 (50348827)
Co-Investigator(Kenkyū-buntansha)	馬場満久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 (10773715) 澤田弘崇国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 研究開発員 (70392842) 加藤裕基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 (70538587) 佐藤泰貴国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 助教 (70726760)
Project Period (FY)	2018-10-09 – 2021-03-31
Keywords	テラメカニクス / レゴリス / 粉粒体 / ダイナミクス / 微小重力環境
Outline of Final Research Achievements	In order to obtain basic data of interaction between granular matter and fluid in low gravity environment, 10 drop tower tests were performed with the drop tower facility (ZARM) in Germany in cooperation with DLR. In 3 times, when a disk such as a landing pad impacts perpendicularly to silica sand No.8 at approximately 0.5 m/s, and in 4 times, when a corer mechanism which is one of the mechanisms for collecting samples from celestial body under microgravity is penetrated into granular matter at about 5 m/s. Through these experiments, we obtained the data for the validation of the model estimating the reaction force from granular matter. In the remaining 3 times, liquid was enclosed in a container simulating a bare tank, and the operation with speed change on the assumption of a planetary lander was applied to a container, and the results for the measurement of sloshing load and CFD verification were obtained.
Free Research Field	機械力学制御
Academic Significance and Societal Importance of the Research Achievements	研究成果は，一つは，真空と微小重力環境を合わせた複合的に異なる環境での粉粒体運動への影響評価を行い，得られた単純な反力推定モデルは，テラメカニクス分野でも過去にないものと予想され，従来モデルとの違いによるメカニズムの再認識にも貢献できると考えられる．次に，球形タンクに閉じ込められた液体が表面張力優位になることを想定し，その状態へ着陸を模擬した衝撃加速度を与えた際の流体重心位置の変化とタンクへの反力を観測した．これは，0Gから着陸衝撃，そして微小重力加速度に戻るという小惑星探査特有の加速度遷移を受けた流体の運動であり，稀有な条件で流体の運動が観測されたことの価値は計り知れない．