Modeling the Interaction between a Rocket Plume, Scoured Regolith, and a Plume Deflection Fence

As a lunar lander approaches the surface, the impinging exhaust gases entrain regolith into a high velocity spray. This two-phase spray can be damaging to nearby structures, such as a lunar outpost. One way of mitigating this damage is to use a berm or fence to shield nearby structures from the dust spray. In this work, we use a coupled continuum - DSMC (direct simulation Monte Carlo) solver to simulate the gas and dust flow fields. A continuum solver, DPLR, is used to model the internal nozzle flow from the nozzle throat out to the continuum regions of the underexpanded exhaust in the near vicinity of the engine. As the rocket exhaust expands further towards vacuum, continuum assumptions break down and kinetic equations are used. Additionally, a dust - gas collision model that conserves momentum and energy transfer between the gas and dust grains has been implemented into the kinetic solver. The distance of the deflection fence from the landing pad is studied parametrically and the corresponding gas and dust flow fields are analyzed. Additionally, the sensitivity of the model to the dust - fence coefficient of restitution is studied when the fence is located 15 m off axis.