DSMC Simulation of Exhaust Dust Particles

Abstract

When a lunar module approaches the lunar surface, the plume from the nozzle hits the lunar surface and the flow is converted into continuum to transition or free molecule flow. Due to hitting of gas on lunar surface large number of dust particles are displaced and accelerate in upward direction. These dust particles are irregular in shape and size and also abrasive. Due to dust deposition on the space vehicle sevral problem occurs like false instrument reading, obstruction of solar panels, camera vision and so on. Due to conversion of flow from continuum to transition, this type of flow cannot be simulated by traditional method CFD so for that Direct Simulation Monte Carlo (DSMC) method is proposed by Bird (1964).

The DSMC method for dust particles trajectories shown in various literatures. The developed simple DSMC code is benchmark with micro channel flow and done different parametric study with variation of pressure and aspect ratio. In the present work, only exit flow of nozzle condition is simulated by DSMC method. Then DSMC code is modified for the nozzle flow gas. Different Radial velocity profile drawn for the different radial position and different hovering altitude of nozzle. The mass flux of eroded lunar dust is scaled with the dynamic pressure above the surface. DSMC solver has been developed such that it has capability of simulating interaction between the dust particles and the gas molecules. Then Dust-Gas coupled code is developed and find validate with different parameters. Three different sized dust particles have been considered for entrainment. A one way coupling of gas flow on dust particles have been done where force of nozzle gas flow acts on dust particle and dust particles are displaced. In present study radial velocity will be finding by using coupling of dust and gas coupling code. A different sized dust particle should be simulated with different nozzle height.