Droplet transient impact pressure in plasma spraying

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.