Analysis Of Dynamical Features Of Droplet Impact Onto Spherical Liquid Film

The phenomenon of droplet impact is widespread in nature and industrial fields, so there are very important academic meanings and application value of engineering to make research on this phenomenon. In this paper, there is experimental research on spreading of single droplet impact on spherical liquid film and numerical simulation of single droplet impingement on spherical liquid film with splashing; and also numerical simulation of shapes of droplets and liquid film after double droplets impact on spherical liquid film. The main contributions are as follows:(1) Experimental results indicate that:when single droplet impacts on spherical liquid film, edge of spread does not retract as when single droplet impacts on flat surface; spreading diameter and area increase with the increasing of impact velocity; spreading diameter and area decrease with the increasing of viscosity.(2) In numerical simulation, results of splashing after single droplet impingement on spherical liquid film indicate that, the expansion angle of impact on spherical liquid film is larger than that of impact on flat surface, the liquid sheet shapes of impact on spherical liquid film are like bowl; with increasing of the impact velocity, the liquid sheet height and diameter increases; when film thickness increases, the liquid sheet height increases, while the diameter decreases; when We remains the same, at late period of impingement, the larger Re is, the larger non-dimensional liquid sheet height and diameter are; at small impact velocity, the height and diameter increase with decreasing of surface tension; liquid sheet height of impact on flat liquid film is not always larger than that of impact spherical liquid film, but it takes longer to reach the maximum height, after that it decreases quickly at a short time; however after liquid sheet of impact on spherical liquid film reaches the maximum height, it decreases more tortuously and slowly than that of impact on flat liquid film.(3) Numerical simulation results of double droplets of different spacing impingement on spherical liquid film indicate that, when the spacing is large, there is jet flow in the neck region; while this jet flow does not appear when the spacing is small.