水平表面气流剪切作用下的水膜厚度

Thickness of water film driven by gas stream on horizontal plane

飞机结冰表面上的液态水受气流吹拂作用会发生向后溢流,从而影响结冰区域范围及防冰系统设计;为了获得水膜流动规律,对水平平板表面上气流剪切驱动的水膜流动进行了实验测量和建模分析。通过水膜流动风洞试验台产生高速气流驱动水膜的流动,使用色散共焦位移计测量同一位置的水膜在不同时刻的厚度变化,结果表明气-液界面由底层薄水膜和多种尺度的波动组成,具有变化速度快随机性强的特点。通过水膜厚度随气流速度及水膜雷诺数的变化规律,发现平均水膜厚度与两者均呈现出单调非线性的依赖关系。基于薄水膜流动理论和平均水膜厚度实验结果,提出了高速气流剪切作用下的气-液波动界面剪切因子计算式,适用于风速17.8~52.2m/s,水膜雷诺数26~128之间的平板水膜流动计算。

Liquid water on the surface of aircraft will run back under the effect of the airflow,resulting in redistribution of ice accretion and anti-icing heat flux.Experimental measurement and modeling analysis are conducted to investigate the flow behavior of shear-driven water film on the horizontal flat substrate.The water flow film is driven in a wind tunnel,and the instantaneous thickness is measured in the same location using a laser focus displacement meter based on confocal chromatic technique.It is found that the interface between the gas and liquid phases consists of underlying thin film and multiple scale fluctuations.The variation relationship of the film thickness between the wind speed and film Reynolds number is also obtained.Results show that the average film thickness depends monotonically on these two factors.Based on film flow model and experimental data,a new correlation for calculating the air shear stress above a thin film is proposed and validated by comparison with previous studies.The correlation can be applied for water film thickness calculation over a range of wind speed（17.8-52.2m/s）and water film Reynolds number（26-128）.