泡内气体热力学性质对空泡溃灭的影响

THERMODYNAMIC INFLUENCES OF BUBBLE CONTENTS ON BUBBLE COLLAPSE

数值研究固壁附近轴对称空泡溃灭问题.忽略泡内气体与周围流体之间的质量和热交换,假设气体瞬时处于热平衡状态,通过引入不同的热力学模型,考察泡内气体在空泡溃灭过程中的作用.采用原始变量的Navier-Stokes方程作为流场的控制方程,用流体体积方法跟踪运动空泡壁.数值结果显示空泡溃灭过程中,伴随空泡变形,空泡发出多个高压脉冲和高速射流.对于不同的热力学模型,等温,绝热和准绝热过程,绝热过程能够最大程度抑制空泡溃灭,从而减弱空泡溃灭对固壁造成的空蚀破坏.在绝热及其类似过程中,出现空泡回弹现象.

On the assumption that mass and heat transfers were neglected and instant thermal equilibrium was satisfied, different thermal state models for bubble contents were introduced when numerically studying a bubble axisymmetrically collapsing near a rigid wall. Fluid fields were controlled by full Navier-Stokes equations. Moving bubble walls were tracked by the volume of fluid method with piecewise linear interface construction and time unsplit propagation. Detailed dynamics information of bubble collapse, such as pressure pulses and high-speed micro fluid jets, was obtained. Among the thermal state models： isothermal, adiabatic and pseudoadiabatic, adiabatic processes led to the most severe restraint to bubble collapse and substantially reduced cavitation erosion in some cases. In adiabatic processes and those similar, bubble rebounds appeared.