液滴冲击移动液膜的数值研究

Numerical Study of Droplet Impact on Moving Liquid Film

关键词:  移动液膜  耦合的水平集-流体体积法  两相界面  冠

Key words:  Moving liquid film  Coupled level set-volume of fluid method  Two phase interface  Crown

摘要:

为了研究液滴冲击移动液膜问题，建立了三维不可压缩层流计算模型，基于耦合的水平集-流体体积法对两相界面进行追踪，探讨了液膜速度和厚度、液滴直径和速度对冲击移动液膜过程的影响。研究表明：液膜静止时，冲击结果是对称的，而液膜移动时，冲击结果变为非对称；液膜速度对冠上游生长具有增强效应，而对冠下游具有抑制作用，增加液膜速度冠的上游高度增加、下游高度减小，内径增加；液膜厚度增加，液膜与壁面的粘性损失减小，吸收冲击动能的能力增强，当无量纲液膜厚度小于1时，冠的上、下游高度均随着液膜厚度的增加而增加，否则相反；当无量纲液膜厚度小于0.5时，冠内径随着液膜厚度的增加而增加，否则反之；随液滴直径和速度的增大，冠的高度和内径均增加。

Abstract:

To investigate the problem of droplet impact moving liquid film, a three-dimensional incompressible laminar flow model was established. The two-phase interface was tracked based on the coupled Level Set- Volume of Fluid method. The effects of liquid film velocity and thickness, droplet diameter and velocity on the impact on the moving liquid film process were discussed. The results show that when the liquid film is stationary, the impact results are symmetrical. While the liquid film moves, the impact results become asymmetrical. The liquid film velocity has an enhanced effect on the upstream growth of the crown, while it has an inhibitory effect on the downstream of the crown. With the increase of the liquid film moving velocity, the upstream height of the crown increases, the downstream height decreases, and the inner diameter increases. The thickness of the liquid film increases, the viscous loss between the liquid film and the wall surface decreases, and the ability to absorb the impact kinetic energy is enhanced. When the non-dimensional liquid film thickness is less than 1, the crown height increases with the increase of the liquid film thickness, otherwise the opposite is true. When the non-dimensional liquid film thickness is less than 0.5, the crown inner diameter increases with the increase of the liquid film thickness, otherwise the opposite is true. With the increase of droplet diameter and velocity, the height and inner diameter of the crown increase.