Gas-particle two-way coupled method for simulating the interaction between a rocket plume and lunar dust

During the landing process of lunar landers, the lunar surface is eroded by the exhaust plume and a large amount of lunar dust entrained into a high-velocity spray. This high-speed lunar dust can have many adverse effects on the normal operation of both the lunar lander and any potential lunar surface facilities. It is necessary, therefore, to develop better ways to model this interaction between the plume and the lunar dust. This paper details the development of a macroscopic gas-particle two-way coupled method for simulating the interaction between the plume and the lunar dust, combining a dynamic method for simulating particle motion with the direct simulation Monte Carlo method for the rarefied plume flow field. This method considers macroscopic aerodynamic forces, convective heat transfer from the plume to the lunar dust, and the reaction of lunar particles to the plume, based on the principles of momentum and energy conservation and the interaction between the plume and its particles; it can meet the conservation conditions at each time step. A microscopic gas-particle two-way coupled method is also adopted to compare with the macroscopic method. This method considers collision behavior, momentum, and heat transfer to particles at the microscopic level, and realizes the effects of solid particles on gas by considering the behavior of gas molecules reflecting on the particle surfaces. The macroscopic simulation results show that particle size has a large influence on their spatial distribution. The results indicate that the particles decelerate as they interact with gas molecules; the particles also delay gas expansion. The results of the microscopic method differ from this method (e.g., slower particle velocities), due to its different theoretical basis. The results obtained by the macroscopic method appear to be more realistic, and this method can better demonstrate the serious impact of lunar dust on the lander and the surrounding environment.