柱坐标系下准三维液滴撞击壁面的数值分析

Numerical Simulation of Quasi-Three-Dimensional Droplets Impacting on Wall in Cylindrical Coordinate System

关键词:  柱坐标系  VOF模型  准三维液滴  铺展系数  二次铺展

Key words:  Cylindrical coordinate system  VOF model  Quasi-three-dimensional droplets  Spreading factor  Secondary spreading

摘要:

液滴撞击壁面现象广泛存在于自然界与工程领域。为研究其运动特性，基于柱坐标系与VOF模型，对准三维液滴撞击固体壁面过程进行模拟。该方法实现了三维到二维的合理简化，模拟与实验结果较为吻合，铺展系数约为2.1。在此基础上，对单液滴撞击固体壁面过程进行了多工况模拟，模拟表明液滴在速度和直径较大情况下铺展系数较大。相反，在表面张力系数和接触角较大情况下铺展系数较小。最后，对双液滴相继撞击壁面的过程进行了模拟，发现液滴在铺展过程中出现了二次铺展现象，并探究了速度和液滴中心间距对铺展特性的影响。结果表明，双液滴在速度和液滴间距较大的情况下铺展系数较大。

Abstract:

The phenomenon of droplets impacting on the wall widely exits in nature and engineering. To this end， the dynamic characteristics of quasi-three-dimensional droplets impacting on the solid wall were simulated by adopting Volume of Fluid （VOF） model in the cylindrical coordinate system， which has realized the simplification of three-dimension to two-dimension. The results show that the algorithm matches the experimental results well and spreading factor of droplet is about 2.1. On this basis， the algorithm was adopted to simulate the multiple cases of a single droplet impacting on the solid wall. It is concluded that the spreading factor appears larger when the velocity and diameter are larger. On the contrary， the spreading factor appears smaller when the surface tension coefficient and contact angle are larger. Finally， the process of two droplets successively impacting on the solid wall was simulated to explore effects of velocity and spacing between droplets on dynamic characteristics. It is found that droplets appear secondary spreading during the spreading process. Moreover， the droplets appear larger spreading factor under the conditions of higher velocity and spacing between droplets.