热非平衡效应与切应力耦合作用下波状液膜流的稳定性

当液体薄膜流界面同时存在切应力和相变时，切应力和相变引起的非热平衡效应将改变液膜的流动状态和界面力平衡状态，二者的相互耦合将使流体动力学特性和稳定性更为复杂。基于完整边界条件，采用参数摄动法，建立了沿倾斜壁面下降的热非平衡效应与切应力耦合作用下的二维液膜流动的Orr-Sommerfeld方程，得到波速和扰动增长率的表达式，着重分析了相变和切应力的影响。结果表明：冷凝状态及其相变强度的增加使得液膜的稳定性得到加强；而蒸发状态及其相变强度的增加导致液膜稳定性减弱；反向切应力有利于流动稳定，正向切应力不利于流动稳定；热非平衡效应不仅影响扰动增长率，而且对临界波数和临界雷诺数也有影响。

Stabilities of Wavy Liquid Films Under Effects of Thermal Non-equilibrium and Shear Stress

The shear stress and thermal non-equilibrium effect occurred by phase change at the interface remarkably affect the flow state and interfacial force balance of liquid films, and the characteristics of hydrodynamics and flow stability tend to be extremely difficult under the coupling effect. The Orr-Sommerfeld equation of the two-dimensional surface waves of the liquid films falling down an inclined wall was established with perturbation method based on the complete boundary conditions. The wave velocity and perturbation growth rate were given and the effects of shear and phase change were investigated. The results show that the flow stability maybe enhanced by condensation and its intensity and decreased by evaporation and its intensity. The flow stability tends to be stable with countercurrent shear and to be unstable with cocurrent shear. The perturbation growth rate, critical wave number and critical Reynolds number are affected by thermal non-equilibrium effect.