Measurements of Surface Accommodation Coefficients for Rarefied Aerodynamics

Abstract

At Japan Aerospace Exploration Agency (JAXA), a hypersonic rarefied wind tunnel (HRWT) has been developed for rarefied aerodynamic measurements. Rarefied aerodynamics need to be accurately estimated for a precise determination of its flight path or landing site in order to improve the feasibility of space missions, such as a landing mission to Mars, Super Low Altitude Test Satellite, etc. In this work, we have first investigated rarefaction effect on pitot tube measurements experimentally and numerically to improve the understanding of flow characteristics in HRWT. Second, the measurement schemes have been developed by using pendulous models for accommodation coefficients. Consequently, we have successfully demonstrated measurements of accommodation coefficients for several metallic and carbon-related materials, and the determination of accommodation coefficients results in the improvement of rarefied aerodynamic predictions.