The Flow Field Measurement In Gas-solid Dilute Phase And Bubble Behavior Based On Image Processing

As one of most important forms in multiphase flow, gas-solid two-phase flow widely exists in modern industrial process, such as non-ferrous metal, metallurgy, building material, electric power, chemical engineering and food industry, etc. Gas-solid fluidized bed is a typical two-phase flow system, dilute phase and dense phase coexist in gas-solid fluidized bed, so the motion between gas phase and solid phase in fluidized bed is very complicated. Because the velocity of particles directly affects particles residence time in the bed, solid mixing and mass transfer, study on the velocity field of the fluidized bed is great significance. Particle velocity measurement method has a significant impact on accuracy of the velocity measurement. In addition, as one of the most basic features in the low-speed fluidized bed, the bubble phenomenon causes a fast enough mixture of particles to enhance the contact efficiency between gas phase and solid phase and provides a good mass and heat transfer behavior.Particle tracking velocimetry technique is studied in the velocity field of the determination of dilute phase, in addition, the bubble movement in fluidized bed is analyzed based on image processing.Firstly, particle motion images of dilute phase fluidized bed and bubble motion picture images are obtained in Fluidized bed gas-solid flow bench by using high-speed camera. Then, the image sample is preprocessed. Secondly, Particle tracking velocimetry technique in the velocity field of the determination of dilute phase is analyzed, according to the particle feature matching, one particle matching method is proposed based on geometric feature similarity and similarity of inertia moment; according to intelligent algorithms matching, another particle tracking velocimetry algorithm is proposed based on particle swarm optimization and Hopfield neural network. The two methods are taken to measure the particle velocity in the particle images of dilute phase, the measurement results show that both the proposed methods are effective. Finally, three of the bubble image sequence are selected, such as bubble rising, aggregation and splitting, the bubble motion behavior in fluidized bed is studied by using image processing technology, parameters trends and variation of the bubble size, speed, deformation parameters in the three of the bubble image sequence are analyzed. The motion parameters of the bubble are analyzed, and the results provide a strong condition for the deep study on the behavior of the bubble mechanism and vulcanization process of the fluidized bed.