Three-dimensional Visualization Of Bubbly Flow Based On Planar Fluorescence Imaging

The bubbly flow exists widely in the fields of petroleum,chemical industry,metallurgy,energy,medicine and other industrial production process.The research on flow parameters and mechanism has an important influence on the rational development and safe production of resources.The research on the flow structure and flow characteristics in the bubbly flow,especially in the dense bubbly flow,is still a difficult problem to be solved urgently.A planar fluorescence imaging method based on the high-speed laser scanning and measuring system is presented to capture the bubble fluorescence image,scan the slice image and reconstruct the three-dimensional structure,which effectively realizes the three-dimensional visualization of the dense bubbly flow and enlarges the size range of the measurable bubbles.Besides,according to the reconstruction of flow field,the flow parameters such as void fraction and interfacial area concentration are analyzed.The mechanism of the void fraction distribution is analyzed by the lateral force of bubble.The work includes the following aspects:1.In order to detect the dense bubbly flow,the high-speed laser scanning and measuring system is used to measure the dense bubbly flow.In the whole process,the measurement principles and mathematical models are analyzed.The error analysis is also implemented according to the system parameters.2.The principle of imaging in the fluorescence plane and the mathematic model of the optical path are analyzed in detail.The high-speed laser scanning and measuring system is used to obtain the slice images of the dense bubbly flow and to extract the effective characteristic information of the bubble flow slices.The three-dimensional visualization of dense bubbly flow is finally realized.3.Aiming at the problem of laser light path deflection,which is caused by different refractive index,the refractive index matching method and FEP material are adopted to reduce the optical path refraction effectively.The influence of optical path deflection on the experimental results is also analyzed.4.According to the results of three-dimensional reconstruction of dense bubbly flow,the flow parameters such as void fraction and interface area concentration are analyzed,and the mechanism of void fraction distribution is analyzed by the lateral force of bubbles.