二维剪切液膜流表面波的线性稳定性特征

Characteristics of linear stability of two-dimensional sheared interfacial waves of falling liquid films

当气液界面存在气流剪切作用时,将在不同程度上影响液膜流动的水动力学特征和流动稳定性。基于层流剪切液膜流动的稳态解,分析了切应力对液膜流动状态的影响。采用积分法,建立了沿倾斜壁面下降的二维剪切液膜流表面波扰动演化方程,模型中包含界面切应力、雷诺数、波数和倾角等参数的影响。研究表明:行波和惯性波的波速受均雷诺数和切应力的影响;同向切应力为不稳定性因素,逆向切应力的稳定性影响与雷诺数有关;同向切应力使临界雷诺数减小,逆向切应力使其增大,切应力对临界雷诺数的影响在不同倾角下也有所不同。

The flow dynamics and stability of falling films under effect of a gas flow are obviously influenced by the shear stress at the interfaces. The solution of base state for the sheared film was obtained and the influence of shear on flow regime was investigated in present paper. The evolution equation of the two- dimensional waves on liquid films was established with the integral approach. The effect of shear stress, Reynolds number, wave number and inclined angle were included in present model. Investigation shows that the wave celerity of traveling waves and inertial waves are related with Reynolds number and interfacial shear. The film flow tends to be unstable under the cocurrent shear, and the effect of countercurrent shear on stability is notably different under Re. The critical Reynolds number decreases under the corcurrent shear and increases under the countercurrent shear, and the effect of shear on the critical Reynolds number is also related with inclined angle.