Abstract: Considering that the thermal effects of the vacuum plumes may be induced by the variable thrust engine during the landing process of the lunar probes, the method of coupling the differential solution of the N S equation and the direct simulation Monte Carlo (DSMC) are used to solve the continuous flow region and the rarefied flow of the plume field. The plume aerodynamic heat flux distributions on the surface of the probe at different states during the landing process are obtained, and the thermal effects of the plume on the probe at different heights and slopes are analyzed. The influence of the plume on the probe due to the special conditions such as the inertia when falling on the moon and the delayed tailing of the engine is studied. The numerical simulation results show that the aerodynamic thermal effect of the plume on the probe increases sharply with the decrease of the distance between the engine outlet and the lunar surface. As the distance decreases to 0.434 m, the maximum heat flux is 429 kW/m 2. The slope of the lunar surface weakens the thermal effects of the plume. The research results can provide support for the formulation of the probe shutdown strategy, input for the thermal protection of crucial parts of the probe and services for the overall design optimization of the probe.

Key words: Lunar probe, Landing process, Vacuum plume, Plume thermal effect