带相变气液界面Richtmyer-Meshkov不稳定性的数值模拟研究

Numerical investigation of the Richtmyer-Meshkov instability for the vapor-liquid interface with phase change

本文使用近期提出的一种带相变清晰界面方法,针对有无相变效应存在时的气液界面Richtmyer-Meshkov不稳定性问题进行了数值模拟研究,分析了单模正弦扰动界面在激波冲击下的波系结构和界面演化机制.文中首先模拟了激波冲击air/SF_(6)界面以及水柱的经典算例来检验数值方法的可行性,数值模拟和实验结果总体上相吻合,表明目前的方法能够精确捕捉气液界面Richtmyer-Meshkov不稳定性发展过程中的界面流动演化特征.接下来,分别研究了三种不同马赫数激波冲击下无相变、蒸发以及冷凝共十三种工况下气液界面Richtmyer-Meshkov不稳定性的发展异同.研究表明,与air/SF_(6)界面的情况不同,由于气液界面之间存在巨大的声阻抗差异,界面不稳定性发展过程中会形成特殊的双尖钉结构.相变过程对界面变形产生的影响表现为蒸发效应抑制界面不稳定性的发展,而冷凝效应则促进界面不稳定性的发展.最后,通过比较数值模拟结果和已有的线性模型,冲击模型能够较好地预测气液界面不稳定性发展前期的线性增长,而有关后期的非线性增长阶段还有待进一步研究.

In this paper,using a recently proposed sharp-interface method for compressible multiphase flows with phase change,we numerically study the Richtmyer-Meshkov instability problem of the vapor-liquid interface,both with and without phase change.The wave structures and the interfacial evolution mechanism of a single-mode sinusoidally perturbed interface under the impact of a shock wave are analyzed.First,the classical air-SF_(6)interface Richtmyer-Meshkov instability and shock water column interaction are simulated in the paper to validate the feasibility of the numerical method.The numerical simulations and experimental results are generally in good agreement,indicating that the present method can accurately capture the interface flow evolution characteristics during the development of Richtmyer-Meshkov instability.Next,we investigate the similarities and differences in Richtmyer-Meshkov instability at the vapor-liquid interface under thirteen conditions:no phase change,evaporation,and condensation with three different Mach numbers.It is shown that,unlike the air-SF_(6),a double spike structure is formed during the development of interfacial instability due to the large acoustic impedance difference at the vapor-liquid interface.And the phase change process affects the local deformation of the interface,as the evaporation effect inhibits the development of the interfacial instability,while the condensation effect promotes the development of the interfacial instability.Finally,we compare the numerical simulation data with the existing linear model and find that the impulsive model can predict the linear growth of the early stage,while the nonlinear growth of the later stage will be investigated further.