| Gas-liquid two-phase flow is one of the most common multiphase flows in engineering.The gas flow velocity of the wavy regime and annular regime is so large that the disturbance wave comes into being on two-phase interface.The disturbance wave carries the quality of liquid phase.Therefore,the study of the characteristic parameters of the disturbance wave is of great significance for understanding the flow mechanism and the evolution law of the gas-liquid two-phase flow.Compared with electrical and optical methods,ultrasonic methods have the characteristics of simple structure and strong adaptability to working conditions.In this paper,the ultrasonic gas-liquid interface measurement system and data processing algorithm are designed for the characteristic parameters of disturbance wave of gas-liquid two-phase wavy regime and annular regime in horizontal flow,such as liquid film thickness,wave velocity,etc.the main work is as follows:1.The method of measuring the film thickness of the literature is summarized.Ultrasonic pulse echo method cannot measure thin liquid film thickness,and traditional resonance method is susceptible to multiple echoes and noise.In order to improve their shortcomings,the main-frequency ultrasonic resonance method is proposed.The method is applied to the measurement of the liquid film thickness of the plexiglass-water-air three-layer medium in the gas-liquid two-phase flow,and it can measure thin film thickness of 0.2mm.2.The gas-liquid interface measurement system is designed for the disturbance waves in horizontal flow,such as liquid film thickness,wave velocity and the asymmetry of circumferential liquid film distribution.Firstly,the hardware design of synchronous excitation,transceiver isolation and echo signal amplification filtering are realized of two-channel ultrasonic transducer with 5MHz center frequency.Secondly,the C program of MSP430,the LABVIEW program of data acquisition board and the MATLAB data processing program of computer are designed.Finally,the accuracy and reliability of the gas-liquid interface measurement system were verified by static experiments.3.The characteristics of disturbance wave in horizontal gas-liquid wavy regime and annular regime are studied by experimental methods.Firstly,based on the Baker regime pattern,220 experimental flow points were selected from five pressure points of 0.1~0.7MPa.Secondly,experiments were carried out on Tianjin University wet-gas test system(medium pressure).Finally,the variation of the liquid film thickness,wave velocity and circumferential distribution symmetry characteristic parameters of the disturbance wave with the gas-liquid ratio and system pressure are analyzed.4.According to the Levenberg-Marquardt optimization iterative algorithm,the Kumar wave velocity model is improved,and a new wave velocity model is established.The model is compared with experimental wave velocity values and literature model data under different pressures.The MAE(Mean absolute error)is 6.179% and 15.563%,respectively,which verifies the extrapolation and applicability of the model. |
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