Flow-Induced Vibration Of Complex Gas Pipeline In Compressor Station

With the increase of flow rate and pressure of long-distance gas transmission pipeline,the problem of pipeline vibration in compressor station becomes more and more serious.This thesis focuses on two common structures of gas compressor stations:the inlet pipeline in pigging area and the pressure tapping bypass pipeline at the inlet of compressor.Using numerical simulation method,the gas flow pulsation laws and natural vibration characteristics of two pipe structures are systematically studied,and then the risk assessment of fluid-structure coupled resonance is carried out.Based on numerical analysis,two flow-induced vibration control methods of station pipeline structure are proposed.Firstly,a numerical simulation method for studying flow-induced vibration of gas transmission pipeline is proposed.Large Eddy Simulation(LES)is used to analyze gas flow pulsation,the Laval nozzle model conveying high pressure and high velocity gas is used to verify the accuracy and stability of LES,the effects of grid density and subgrid scale model are investigated,and the DSM subgrid scale model with a calculation error of 5.235% is selected.CAESARⅡ software based on Finite Element Method is used to study the natural vibration characteristics of pipeline structure.The risk of resonance of the pipeline is analyzed by coming the flow and structure results.Then,the validated LES method is used to solve the gas flow pulsation in the inlet blind pipe in the pigging area of the compressor station and the inlet pipe of the compressor at shutdown under different pipeline flow,and the influence of the flow velocity on the frequency and amplitude of the gas flow pressure pulsation in two pipe structures is studied.Through the analysis of the transient vortex structure and pressure contours,the underlying physics of gas flow pulsation are revealed.Subsequently,the resonance risk assessment is carried out in combination with the natural frequency and main vibration mode of the pipeline structure calculated by CAESARⅡ software.The results show that,when the gas pressure pulsation frequency approaches the natural frequency of the pipeline,the resonance phenomenon occurs in the empty pipe(including the ball receiver)behind the ball valve and the pressure tapping bypass pipe at the inlet of the compressor.Finally,two principles for vibration suppression of the pipeline inthe compressor station areproposed.Three structural reinforcement methods are put forward for the vibration pipeline in the pigging area,while a structural reinforcement approach is proposed for the pressure tapping bypass pipeline at the inlet of the compressor.From view point of suppressing vibration,suggestions on the design of pipelines in the compressor station are also given.