| Future space exploration will benefit from a simulation tool that can help mitigate the hazards of rocket exhaust impinging on extraterrestrial regolith covered surfaces and necessitates improved gas-particle and particle-particle interaction models. Developing models, which describe the interaction of rocket exhaust plume with a particle bed, requires experimental data on cratering behavior, specifically on the effects of gravity, jet and particle properties.;In order to model cratering of a particle bed by a turbulent subsonic jet, an Eulerian framework is employed using locally averaged equations of motion along with closure relations describing the solids-phase stress derived from concepts of granular kinetic theory. The particle-phase frictional stresses, which occur at high solids volume fractions and result from sustained particle-particle contacts, are based on critical state theory. A new frictional stress model is developed, which is able to predict the salient trends in crater predictions to changes in jet properties and determine the cratering mechanisms.;Next, a parametric study is presented to investigate the effects of particle properties on crater growth. Effects of particle size, shape, and density on asymptotic crater depth and crater growth over time are analyzed. An adjustment to the scaling function between the asymptotic crater depth and jet and particle properties is developed that captures the effects of particle shape. The particle shape is identified to be a non-negligible particle property for crater growth.;Additionally, cratering experiments were performed to investigate the effects of cratering in lunar conditions. Variable gravity experiments utilizing particles with different intrinsic densities explored the effects of gravity on crater growth and the dominating crater mechanisms. Earth-based cratering experiments of lunar regolith simulants express the importance of bulk density and the percentage of fine particles on crater growth. The crater growth over time and the asymptotic crater depth are explained in terms of the characterized properties of lunar regolith simulants. |
