风驱动下平板水膜表面波动特性实验研究

Experimental Study on Surface Fluctuation Characteristics of Flat Water Film Driven by Airflow

飞机表面在过冷水滴持续撞击下存在未冻结的液态水,液态水在气流驱动下向后发生回流。流动过程中水膜表面波动改变了液体的质量分布,进而影响结冰过程的传热特性。本文针对风速在16.5~45.5 m/s和水膜雷诺数在24.17~96.69范围内,采用了数字图像投影(Digital image projection,DIP)技术进行非侵入式测量,观测平板水膜流动中表面波在全视域内波形发展的过程。同时针对视域内的瞬时信号对波动特性进行分析,阐述了气⁃液界面波参数随风速和水膜雷诺数的变化,包括波峰高度、波峰频率、波速和波峰间距等。结果表明,表面波在水膜流动过程中呈现多种形态,风速增大会破坏原有的周期性波动加剧形态变化,流量增加会提高界面稳定性维持周期性波动。对水膜表面波动特性研究有助于揭示水膜流动过程中波形变化的物理机制,用于优化冰形预测和防冰系统设计。

The unfrozen impinging water on the surface of aircraft will run back under the effect of the airflow.The fluctuation of water film surface will alter liquid distribution,further affecting the heat transfer characteristics during the icing accretion.The digital image projection(DIP)technology is used to provide non-intrusive and full-spatially-resolved measurements of the wavy development during the water film flow.A series of experiments are conducted in the air speeds of 16.5-45.5 m/s and the Reynolds number of water film of 24.17-96.69.The wavy characteristics of the temporally-and-spatially-resolved results are analyzed,which present the variation of the gas-liquid interface wavy parameters with both the air speed and the Reynolds number of water film,including the peak height,peak frequency,wave velocity and peak spacing.The results show that the surface wave will present varied forms in the process of water film flow.The increase of air speeds will destroy the initially periodic fluctuations and aggravate the changes of morphology.However,the increase of flow will enhance the stability of the interface and maintain the periodic fluctuation.This work is helpful to reveal the surface fluctuation characteristics of shear-driven water film,optimizing ice shape prediction and anti-icing system design.