Research On Characteristics And Visualization Measurement Of Horizontal Slug Flow

The horizontal slug flow is an important flow pattern of gas-liquid two-phase flow and widely exists in industrial production,such as natural gas or petroleum transportation systems.The slug flow is characterized by alternating slug bubbles and liquid plugs,and the flow process is often accompanied by the corrosion and vibration of the pipeline.Therefore,the measurement of the flow parameters of the slug flow is essential for the comprehension of flow structure and mechanism,as well as the safety of industrial production.In this paper,based on high-speed photography and image processing technique,the slug flow image is optimized,and the velocity distributions of slug bubbles are measured and analyzed in the slug flow.A method in the frequency domain is proposed to investigate the interface behavior of slug flow.The relationship between the gas and liquid superficial velocity and interface behavior is investigated,and the distribution characteristics of gas-liquid interface are analyzed at different flow velocities.In addition,based on the laser induced fluorescence(LIF)technique,the parameters of the slug flow in the cross-section of the pipe are measured and analyzed,and the threedimensional visual reconstruction of slug bubble is realized.The specific work includes the following aspects:Based on the analysis of slug flow measurement technology at home and abroad,the accurate extraction of slug bubble contour in slug flow is realized,based on the high-speed photography and image processing methods.The effects of interface fluctuation and tail breakup on the measurement of slug bubble velocity are considered comprehensively.Then,the error correction is applied to accurately measure the velocity of slug bubble.According to the interface behavior of the horizontal slug flow,the distribution of the gas-liquid interface is characterized based on the slug bubble thickness,and the power spectrum distribution of the thickness signal is obtained.Moreover,the relationship between the gas-liquid superficial velocity and interface behaviors such as bubble shape,interface fluctuation and tail breakup are investigated.Finally,an empirical model between the maximum spectral amplitude and the gas and liquid phase flow rates is established,based on experimental results and classical velocity models,which can further reveal the relationship between interface behavior and flow parameters.In the horizontal slug flow,the flow parameters of slug flow are measured and analyzed at different gas and liquid velocities by laser induced fluorescence technique.The parameters of slug bubble velocity,length and void fraction,interface curvature of slug flow is measured from the processed fluorescence images,and the phase distribution and interface fluctuation characteristics in slug flow are analyzed in this paper.Finally,high resolution reconstruction of slug bubble is realized based on the interpolation and median fusion algorithm for the visual characterization of slug flow structures.