液滴撞击液膜动力学特性的FTM模拟

采用界面追踪法(front-tracking method)对液滴撞击液膜动力学特性进行数值模拟,通过撞击后的形态演变及内部物理场信息分析,研究了韦伯数和无量纲液膜厚度对界面运动过程的影响,并阐述了撞击过程中形成卷吸现象的机理。研究表明,液滴撞击之后,会在颈部区域产生小射流,该射流是后期水花形成的基础;水平方向上,在撞击影响不到的区域压力不变化,而在射流形成处的颈部附近存在局部压差;液滴撞击液膜时其间的气体层被压缩,在流体黏性和剪切力的作用下,压力高的气层中的气体逃逸速度减慢,从而形成卷吸现象。

Dynamic Simulation of Droplet Liquid Film Impingement by FTM

By using a front-tracking method, the dynamic characteristics of the droplet impact onto liquid film were numerically simulated. Through analysis of the liquid topology evolution and internal physical field information obtained after impacts, the influence of We number and dimensionless liquid film thickness on interface motion was studied, and the mechanism of air entrainment phenomenon in the impact process was expounded. Further researches show that small jets occur in the neck region after impacts, which is the basis of the formation of the crown. In the horizontal direction, the pressure does not change in the area where the impact does not affect, while there is a local pressure difference near the neck of the small jets. During the droplet liquid film impingement, the gas layer is compressed, and under the joint action of fluid viscosity and shearing force, the gas escape velocity in the gas layer with high pressure is slowed down to form a air entrainment phenomenon.