Tracking plume-regolith interactions in near-vacuum conditions

Subramanian, S., Wilson, A., White, C. , Kontis, K. , Evans, D. and Van den Eynde, J. (2024) Tracking plume-regolith interactions in near-vacuum conditions. Physics of Fluids, 36, 013301. (doi: 10.1063/5.0180669)

Abstract

An experiment to track and measure the transient phenomenon of plume-liberated regolith in near-vacuum conditions was performed in a dedicated plume-regolith facility housed at the University of Glasgow. This facility with a total volume of around 82 m3 can simulate a soft or hard landing event on “extraterrestrial” sub-atmospheric pressures. Particle image velocimetry method was used to estimate the ejection velocity and ejected angle of regolith particles, and its limitations are discussed. Glass microspheres that are matched with the size of the Lunar and Martian moon “Phobos” surface regoliths are used as simulants. With an exit Mach number of 6.6, a heated convergent–divergent nozzle represents the lander nozzle. Preliminary results capture ejecta development up to 30 ms from plume impingement. Flow visualization reveals the initial moments of plume boundary growth and regolith ejection. The vector images indicate a triangular-shaped sheet of particles sweeping from the regolith bed at a positive inclination with a local maximum velocity close to 100 m/s. The low-density “Phobos” simulant advances at a higher speed, reaches higher elevations, and covers a larger spatial area compared to a higher-density “Lunar” simulant. Observation of the crater formation reveals the difference in cohesive forces between the selected simulants. A higher inclination of particle ejection of more than 50° adjacent to the jet indicates particle entrainment originating from the interior of the crater. Stream traces reveal the deflection of ejected particles upon impingement on the lander surface at close proximity.

• Item Type: Articles
• Additional Information: The authors wish to express gratitude towards the European Space Agency for funding this research, and BUSCH UK for their ongoing assistance in ensuring the efficient functioning of the facility.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: White, Dr Craig and Kontis, Professor Konstantinos and Wilson, Mr Andrew and Subramanian, Mr Senthilkumar
• Authors: Subramanian, S., Wilson, A., White, C., Kontis, K., Evans, D., and Van den Eynde, J.
• College/School: College of Science and Engineering > School of Engineering > Autonomous Systems and Connectivity
• Journal Name: Physics of Fluids
• Publisher: American Institute of Physics
• ISSN: 1070-6631
• ISSN (Online): 1089-7666
• Published Online: 02 January 2024
• Copyright Holders: Copyright © 2024 The Authors
• First Published: First published in Physics of Fluids 36:013301
• Publisher Policy: Reproduced under a Creative Commons licence