Study On The Laser Scanning Based Measurement Of Dense Bubbly Flow

Gas-liquid two phase flow exits in many industry fields,such as petroleum,metallurgy,biology,chemical engineering,aerospace,automobile etc.The study of its characters is of great significant.Study on the measurement of gas-liquid two phase flow has become a scholastic hotspot at present.Traditional methods are difficult to measure the complicated flow characteristics caused by the interaction of bubbles in the dense bubbly flow.Therefore,the research on measurement methods aimed at dense bubbly flow is of great importance.In this paper,the laser scanning based measurement of dense dispersed phase gas-liquid two phase flow is researched.Based on the principle and mathematical model of the laser scanning measurement system,the measure error is analyzed.With the technology of high-speed camera photography and digital image processing,according to characteristics of dense bubbles laser light sheet image,the three-dimensional(3D)reconstruction of the dense bubbles structure is amplified.A stereo matching method aimed at dense bubbles is proposed.The details are as flows:1.The mathematical model of laser scanning measurement system is set up.The error of linearization is analyzed and the mean square error(MSE)is 0.104,then the influence on measure result of the error is studied.2.The relationship between the pixel pitch and the actual physical size is obtained after camera calibration.Then the influence on slice images of Gaussian distribution of light intensity and camera exposure time is study,and the image preprocessing method which can reduce the impact is developed.3.According to characteristics of dense bubbles laser light sheet image,a interpolation algorithm is improved.And the 3D structure of dense bubbles is reconstructed.The reconstructed result shows the improved algorithm can reflect the 3D structure of dense bubbles more veritably.4.The measurement experiment aimed at analyzing flow characteristics of dense bubbles is studied.According to the actual situation,the feasibility of the experiment is analyzed.Then a multi-restrictions stereo matching method aiming at dense bubbles is proposed.