热非平衡效应下蒸发或冷凝剪切液膜流的非稳定性

热非平衡效应下的液体薄膜流在相变和剪切力耦合作用下，气液交界面处的边界条件更为复杂，在一定程度上影响着液膜流动的非稳定性。通过建立热非平衡效应和剪切力耦合作用的液膜流动控制模型，得到扰动增长率与热非平衡效应、相变强度、剪切力、雷诺数和倾角间的理论表达式，探讨了不同因素对流动非稳定性的影响规律。研究表明，界面蒸发状态所引起的扰动将加剧流动非稳定性，而冷凝状态减缓其非稳定性；热非平衡效应及其相变强度的影响在小雷诺数下较为明显，随雷诺数增加，其影响逐渐减弱。扰动增长率随倾角呈单峰曲线变化，垂直液膜处于最不稳定状态，而水平流液膜最有利于减小流动的非稳定性；正向剪切力使表面波非稳定性增强，反向剪切力使其非稳定性减弱。

Instability of Evaporating or Condensing Sheared Liquid Films Under Thermal Non-equilibrium Effect

The boundary conditions of liquid wavy films tend to be complex and the flow instabilities are influenced by the coupled effect of the thermal non-equilibrium and shear stress at the gas-liquid interfaces. The governing model was established for the liquid film flow under thermal non-equilibrium effect and shear stress. The theoretical relation of perturbation growth rate was presented with thermal non-equilibrium, intensity of phase change, shear stress, Reynolds number and inclined angle, and the impacts of above factors on dynamic instabilities were discussed. Investigation shows that flow instability tends to augment under the perturbation occurred by evaporating and to weaken under condensation. The effects of thermal non-equilibrium and intensity of phase change is relatively remarkable under lower Reynolds number and reduce with increase of Re. The perturbation growth rate presents a single-hump curve with the inclined angle, and the flow is in most instable state for a vertical film flow and is in most stable for a horizontal flow. The film flow tends to be instable with cocurrent shear and to be stable with countercurrent shear stress.