喷雾液滴撞击液膜影响参数及流动机理分析

液滴撞击壁面是喷雾冷却中最常见的现象。使用计算流体力学软件中的Volume of Fluid （VOF）模型对液滴撞击壁面过程进行了数值模拟研究，研究了不同参数的液滴撞击壁面液膜过程的水花形态特点，针对水花高度和直径等参数进行了分析，通过运动间断理论和无量纲参数Re和We的变化分析了不同参数对液膜的流动特征和水花形态的影响及水花产生机理。结果表明：大液滴撞击液膜时能够改善液膜的流动状态；过大的液滴速度会产生大量飞溅及表面干涸；液滴撞击薄液膜时，液膜的流动性较好，当0.6<h*<1.2时，液膜的流动性不随液膜厚度改变。

Influencing parameters and film flow mechanism of spray droplet impacting liquid film

The impact of droplets on the wall is the most common phenomenon in spray cooling. The Volume of Fluid (VOF) method in computational fluid dynamics software was used to carry out numerical simulation studies on the process of droplets impacting the wall surface, and the splash shape characteristics of the process of droplets impacting the wall surface liquid film with different parameters were studied. According to the height and diameter of the splash, the influence of droplet parameters and film thickness on splash parameters were analyzed. Combined with the change of splash parameters, the motion discontinuity theory and the change of the dimensionless parameter Re and We were used to analyze the effects of different parameters on the flow characteristics of the liquid film, the shape of the splash and the mechanism of the splash generation. The results showed that when large droplets hit the liquid film, the fluidity of the liquid film can be improved, while the film thickness will be increased. Excessive droplet velocity will produce much splashing and dry up the surface. Increasing the surface tension properly can reduce the formation of secondary droplets and promote the flow of liquid film. Better fluidity of the liquid film can be achieved when the droplets hit a thin liquid film. When the non-dimensional film height is between 0.6 and 1.2, the fluidity of the liquid film does not change with the thickness of the liquid film.