When lunar probes make a landing on the lunar surface, lunar-soil particles will be blown away by the engine plume with a significant collision phenomenon. The hard-sphere model, whose governing equations satisfy the momentum and kinetic-energy conservation equations, is used in research to study collision phenomena among particles having different diameters. The lunar-soil particles with different diameters collide 36.8–153.2 times on average, and the average speed is 50.4–426.7 m/s assuming no energy loss. When the recovery coefficient is reduced from 1.0 to 0.1, the average number of collisions increases by 16.3%–65.7%, and the average speed decreases by 24.2%–49.8%. Furthermore, the number of particle-occupied space grids increases for small-diameter lunar-soil particles as the collision process loses energy but decreases for large-diameter particles. Overall, the collision phenomenon among lunar-soil particles under engine plumes is important because it causes massive momentum and kinetic energy transfers among particles, which alters particle spatial trajectory and distribution.

当月球探测器在月球表面着陆时，月球土壤颗粒将被发动机羽流吹走，并产生显着的碰撞现象。硬球模型的控制方程满足动量和动能守恒方程，用于研究不同直径粒子之间的碰撞现象。不同直径的月土颗粒平均碰撞36.8-153.2次，平均速度为50.4-426.7 m/s，假设没有能量损失。当恢复系数从1.0降低到0.1时，平均碰撞次数增加16.3%~65.7%，平均速度降低24.2%~49.8%。此外，随着碰撞过程失去能量，小直径月球土壤粒子的粒子占据空间网格的数量增加，但大直径粒子的粒子占据空间网格数量减少。总体而言，发动机羽流下的月土粒子之间的碰撞现象很重要，因为它会引起粒子之间的大量动量和动能传递，从而改变粒子的空间轨迹和分布。