空气环境中水滴和半空间弹性体撞击力学行为的数值模拟

Numerical Simulation of Dynamic Behavior of Impact Between Liquid Droplet and Semi-Infinite Solid in Air

通过将拉格朗日方法与欧拉方法相耦合,分析了在空气环境中直径为1 mm、速度为150 m/s的球形水滴对半空间弹性体的撞击过程.通过对液固撞击过程的数值模拟,给出了撞击过程中水滴内部的压力分布及其随时间的变化、液固接触边缘射流的形成及其破碎的过程、被撞击固体的变形特点和等效应力及其随时间的变化.结果表明:水滴和被撞击固体的可压缩性对整个撞击过程有重要影响;在撞击的初始阶段,水滴中产生水锤压力并使固体表面产生相对很大的变形和应力,水锤压力的理论值和数值计算的结果具有较好的一致性,验证了耦合数值计算方法的可行性和精确度;射流出现的时间比激波脱体的时间晚,高速射流对不再平坦的固体表面的强烈剪切作用使固体进一步变形,并且液固接触边缘的压力高于内部的压力.

The impact of a spherical liquid droplet in the domain of air onto a planar semi-infinite elastic solid is simulated with the Lagrangian and Eulerian coupling method, where the droplet＇s diameter and speed are taken as 1 mm and 150 m/s respectively. The pressure and variation with time inside the liquid droplet, the formation and shattering of the jet at the contact periphery, and the deformation and equivalent stress as well as the evolution of the solid are obtained numerical- ly. It is shown that the compressibility of the liquid droplet and the solid plays a dominant role during the impact. At the beginning of the impact, there are water-hammer pressure in the liquid droplet and relatively large local deformation and stress in the impact area of solid. The water- hammer pressure is in good agreement with the theoretical prediction. The validity and accuracy of the numerical methods are verified. The high velocity lateral jet starts to form after shock wave departure. Heavy shearing action of the jet exerts further deformation on the solid which is no longer planar. The pressure at the contact periphery is higher than the pressure inside droplet. These results provide a reasonable explanation for the failure patterns of the solid impacted by high-speed liquid droplet.