Flow Measurement Of Liquid Flow Rate Among The Annular Flow And Analysis Of Liquid Film In Vertical Tee Junction

Gas-liquid annular flow is a common manifold and widely exists in heat exchange equipment in many fields such as refrigeration,chemical industry and power.The liquid flow rate of the annular flow is closely related to various physical processes,so it is of great significance to accurately measure the liquid flow rate of the annular flow in the tube.In recent years,with the development of digital camera technology,the digital silhouette method has been widely used in the field of liquid film thickness measurement,especially in downflow analysis.This method does not contact the two-phase flow in the tube and does not destroy the flow field.T-tubes are used as the basic components to measure the flow of annular flow in the main pipe and the branch pipe respectively.The measuring method is to dye the liquid and use a high-speed camera to photograph the annular flow in the visible light environment.Through the image processing of the image,the liquid flow in the annular flow is measured.Based on Beer-Lambert's law,using the light field filtering algorithm and the perspective transformation algorithm,the thickness of the liquid film on each pixel is calculated according to the law,and the cross-section liquid content is calculated after integration;the cross-correlation image feature matching algorithm is used to select the appropriate Move the window size to find the liquid film velocity in the main branch tube.Finally,after evaluating the velocity of the main branch tube and the stability of the liquid film thickness,the liquid-phase mass flow rate is obtained.After comparing with the experimentally collected data,the measurement error is less than 5%.At the same time,using the measurement method proposed in the paper,the data of the T-tube under fixed conditions and variable conditions are analyzed.Firstly,the images under single conditions were analyzed,and the differences in liquid film thickness and liquid film velocity at different positions in the tube were compared with time;then,the variations of the gas-liquid flow rate,liquid film thickness,and flow velocity in each part of the tube under variable conditions were analyzed.The situation focuses on analyzing the changing law of liquid film parameters when the import working conditions change,and finally concludes the change trend.The results of the study indicate that the liquid film thickness in the three parts of the tube is irregularly fluctuating with time under the working conditions of the experimental range under the condition that the gas-liquid flow rate at the inlet of the T-tube is fixed.The liquid film thickness in the tube fluctuates with time,but the liquid film thickness on the main tube is small and the change is not obvious.However,by calculating the average film thickness of the three parts of the tube at different times,it can be found that the average thickness value of each part is relatively stable.When the inlet gas flow rate does not increase the inlet water volume(ie,the inlet gas flow rate is 130m3/h),the liquid flow rate of the main pipe and the branch pipe increases linearly,and the liquid film thickness in each part of the pipe increases,and the liquid film thickness increases.Since the lower part of the main pipe,the branch pipe,and the upper part of the main pipe are successively reduced,the speed of the liquid film is reduced from the inside of the pipe,the lower part of the main pipe,and the upper part of the main pipe.Under the conditions of increasing the inlet air intake volume(ie,the inlet gas flow rate is 110 m3/h,110 m3/h,and 130 m3/h,respectively),the liquid flow in the branch pipe increases,while the flow in the upper part of the main pipe decreases;With the increase of the inlet flow rate,the liquid film thickness in each part of the T-shaped tube showed a decreasing trend,while the liquid film velocity showed an increasing trend.In this paper,a basic research on the flow measurement method for measuring annular flow is made,and the experimental results are analyzed,which provides ideas and methods for further research in the future.