基于CFD的单液滴低速撞击动力学特征研究

Dynamic characteristics of single droplet impact at low velocity based on CFD

利用VOF界面追踪方法模拟液滴低速撞击亲水基板的沉积过程,分别对液滴运动、铺展、迟豫及平衡四个阶段的形态演化过程及动力学特征进行了分析。通过对液滴沉积过程中液相相态、压强、速度、铺展因子及无量纲液膜厚度五个关键因素分别进行讨论。模拟结果表明:液滴因撞击产生的压强变化与射流速度变化在时间上不一致,压强比射流速度提前趋于平缓,液滴铺展后期所需的能量由球缺部分的动能提供。

VOF interface tracking method was used to simulate the deposition process of droplet with a low velocity impacting hydrophilic substrate.The morphological evolution and dynamic characteristics of droplet motion,spreading,relaxing and equilibrium were analyzed.The five key factors of droplet deposition,including liquid state,pressure,velocity,spreading factor and dimensionless film thickness,were discussed.The simulation results show that the pressure change caused by the droplet impact is not consistent with the jet velocity change in time.We observed that the variation of pressure reaches the stable state ahead of the jet velocity,and therefore the energy required in the later stage of droplet spreading is mainly provided by the kinetic energy of the spherical part rather than impact pressure.