微小管道两相流流动图像畸变校正研究

Flow image distortion correction for two-phase flow in micro/mini pipes

由于管壁折射的影响,可视化方法获得的微小管道气液两相流流动图像具有一定的畸变,无法准确反映流动信息。通过光路和仿真分析,研究了几种常见状态下图像畸变。结果表明,可视化方法获得的图像相比真实结构为线性放大,放大率随着液相折射率的增加而线性增加,受到管道内径、管壁厚度以及管壁折射率等因素的影响较弱,一般情况下放大率在1.30~1.44之间。进行了毫米级管道下的相含率测量实验,利用该图像畸变校正方法,大幅降低了测量结果的最大绝对误差(2.06,3.14,4.22 mm管径下降幅分别为5.46%,4.66%和5.16%),验证了该校正方法的有效性。本研究揭示了图像畸变作用的多个重要因素,对准确获取微小管道气液两相流的流动信息具有重要作用。

Due to the refraction of the pipe wall,the flow images of gas-liquid two-phase flow in micro-/mini-pipe obtained with visualization method are distorted,which fail to reflect the flow information accurately.The present paper investigates the image distortion under several common conditions through light path and simulation analysis.The results indicate that the images obtained with visualization method are linearly enlarged compared with the real structure,and the magnification ratio increases linearly with the increase of refractive index of the liquid phase.The influences of the inner diameter,wall thickness and refractive index of the pipe are relatively small.The magnification ratio is in the range between 1.30 and 1.44 under normal circumstances.Practical void fraction measurement experiments in millimeter-scale pipes were carried out.With the image distortion correction method,the maximum absolute error of the measurement results is decreased significantly(the decrements for the pipes with inner diameters of 2.06,4.14 and 4.22 mm are 5.46%,4.66%and 5.16%,respectively),which verifies the effectiveness of this correction method.This study reveals the important influence factors of image distortion,which is of great important significance for accurately obtaining the flow information of gas-liquid two-phase flow in micro-/mini-pipes.