等离子喷涂熔滴的瞬时碰撞压力研究

Droplet Transient Impact Pressure in Plasma Spraying

采用数值模拟，研究了等离子喷涂熔滴碰撞基体后，作用在基体表面的瞬时压力分布变化过程和影响因素．研究表明，碰撞压力和熔滴的初始动能存在正比关系，碰撞压力集中作用在基体表面熔滴直径为２ ．５ 倍以内的区域．在该区域以外，碰撞压力值很小。

Numerical study is made for the spreading process of an isothermal droplet impinging on flat substrate surface in plasma spraying by using ′Marker And Cell′ technique. The transient impact pressures on substrate surface after impact are calculated for different droplet conditions. The simulated results show that the transient impact pressure is initially high and concentrates at the contacting area. It then spreads and drops quickly when the droplet flattens out. The maximum pressure is located at the tip of the droplet at the early stage of deformation. The fluid moves quickly along the substrate surface giving rise to lateral flow, the velocity of which is 3 times higher than that of impact velocity. The impact pressure is linearly proportional to the initial impact kinetic energy for a given time and location. It acts over an area, ξ <2.5 of substrate surface. For the area of ξ >2.5, the deformation rate slows down and the fluid mainly moves laterally.