Research On Three-dimensional Dynamic Measurement Technology Of Gas-liquid Two-phase Flow

With the rapid development of society and the continuous progress of science,industrial production and the natural environment related to the gas-liquid flowproblems are more and more intimate. The research on the behavior characteristicsand the spatial movement parameters of the gas-liquid flow are also more profound.Therefore, it is significant to achieve the three-dimensional dynamic measurement oftwo-phase flow.This paper studies the bubble flow measurement technology based on the virtualbinocular stereo vision system, and the annular flow liquid film thicknessmeasurement method based on the high-speed photography. The planar targetcalibration technique was used for virtual stereo vision system calibration. A new3D-PCSS motion matching algorithms was proposed and the three-dimensionalparameters of multiple bubbles were reconstructed. The single bubble spatialmovement transportation equation was deduced further, and then the liquid datescould be inverting solved overall. The details include the following aspects:1. The principle of measurement and mathematical model of the virtual binocularstereo vision measurement system were studied. The planar target calibrationtechnology was used to calibrate the system, and the final spatial measurement error issmaller than0.06mm, and the relative error is smaller than0.62%.2. The bubbly flow measurement based on virtual binocular stereo vision systemwas completed. Image pre-processing procedures and multi-threshold constraintstereo matching were applied to process the original images. A new3D-PCSS motionmatching algorithms was proposed and the multi-bubble in consecutive frames wasmatched by the method. The spatial movement velocity vector field and thetrajectories of multi-bubble were reconstructed.3. The bubble dynamics of gas phase was deeply analyzed based on the spatialmotion characteristic of the bubbles. The mathematical equation for the spatial motionof a bubble was worked out. And the velocity vector of the liquid phase wascalculated. The discrete dates of the liquid velocity were interpolated by thethree-dimensional interpolation method. The overall velocity vector field of the liquidphase was obtained finally. 4. The liquid film thickness of the annular flow was measured based on thehigh-speed photography. The error caused by the refraction and reflection of the backlight was analyzed. The laser-induced fluorescence was combined with the high-speedphotography and finally accomplished the fixed point measurement of the liquid filmthickness.