基于激光诱导荧光的环状流液膜流速测量与分析

Measurement and analysis of liquid film velocity in annular flow based on laser-induced fluorescence

在对传统方法测量和分析液膜特性的基础上,采用激光诱导荧光方法和互相关测量技术,对竖直管道中的液膜流速进行光学测量和分析。基于高速摄影获取气液环状流中液膜图像,采用数字图像处理技术对液膜流动图像进行处理,得到液膜厚度在空间上的分布函数变化曲线,对间隔固定帧频的液膜图像进行互相关处理,进而采用抛物线拟合,有效提高了互相关极值的测量精度。实验结果表明,本文方法非接触、适用面广,可以有效检测环状流中液膜"破断"现象,并准确测量液膜流速参数。

The parameters measurement of liquid film in gas-liquid two-phase annular flow is of great significance for the study of heat and mass transfer and flow characteristics.Laser-induced fluorescence technique based on optical measurement principles to measure film parameters can be simply implemented with high accuracy and without interference of flow fields.Compared with the traditional measurement methods,the method combining the laser-induced fluorescence technique with the cross-correlation technique is developed to measure the liquid film velocity and analyze the flow characteristics.With the aid of digital image processing technology,curves of film thickness at different locations are figured out based on the film images shot by high-speed camera.The flow velocity of the liquid film is accurately measured by processing the images at a fixed interval frame based on the cross-correlation technique.The parabolic fitting technique can be used to estimate the largest correlation coefficient with a higher accuracy and improve the measurement accuracy of film velocity.The experimental results show that the non-intrusive measurement method with a wider range of application can effectively detect the liquid film ＂break-up＂ phenomenon and extract the liquid film flow velocity with a higher accuracy.