柴油液滴撞击热壁面的动态行为特性

In order to analyze the phenomenon of spray droplets impacting on the surface of the piston in diesel engines, a high-speed camera was used to study the dynamic behavior of diesel droplets impact on a heated surface. The results show that when a diesel droplet impacts on a heated surface with different surface temperatures (25~550℃) and different We (25~174), there are four behavioral mode which are the stick mode, the rebound mode, the breakup mode and the breakup-rebound mode. In the stick mode, with the increase of surface temperature, the decrease of droplet viscosity will increase the variation range of droplet spreading factor and dynamic contact angle. With the increase of We, the inertial force of the droplet increase, which in turn forms a larger spreading factor. The rebound behavior of the droplet will occur when the surface temperature exceeds the dynamic Leidenfrost temperature, and the value of dynamic Leidenfrost temperature will increase from 425 to 450℃ as We increases. In the rebound mode, as We increase, the maximum spreading factor and the dimensionless resident time of the droplet increase significantly. Combined with the literature, the prediction equations applicable to multiple working fluids are summarized respectively.