Research On The Internal Flow Pattern And Optimization Of Diffuser In Helico-axial Multiphase Pump

As it has advantages of compact structure and insensitivity to solid particles,the helico-axial multiphase pump is of great significance for its research.The diffuser of helico-axial multiphase pump are the key components for connecting the front and rear impellers.The vortex and gas-liquid separation phenomenon are easily generated in the diffuser flow passage,which affects the overall performance of the multiphase pump.In this paper,the orthogonal experimental design and numerical simulation method are combined to optimize the structure of the helico-axial multiphase pump diffuser to improve the internal flow state of the diffuser and improve the multi-phase pump performance and efficiency.Firstly,based on the existing three-stage helico-axial multiphase pump in the laboratory,the external characteristic test is carried out to study the hydraulic performance under different operating conditions,which lays a foundation for the verification of the accuracy of the subsequent numerical simulation method.Subsequently,numerical simulations were conducted by commercial software ANSYS CFX to explore the gas-liquid flow pattern in the pump.It was found that the obtained performance curve is consistent with the trend of the test results,and the difference is within a reasonable range,which shows the numerical simulations method is accurate.the numerical simulations results shows that there were obvious gas phase separation and liquid phase reflux and vortex phenomenon in diffuser,which affected the normal flow of the fluid and caused excessive energy loss.Aiming at this problem,this paper selects six key parameters to optimize the diffuser structure.The orthogonal experimental design method is used to determine the 25 sets of diffuser structure parameters,and the models are established respectively.The performance is predicted by numerical simulation method.The influence degree of the selected six vane structure parameters on the performance of the compress unit is compared,and the optimal parameters are combined to form a model of the optimized diffuser.The performance prediction shows that the hydraulic performance of the pump after the optimization is improved under various working conditions,the multiphase flow in the pump is more reasonable,the gas-liquid separation phenomenon is greatly reduced.Performance of pump is improved most under the design condition with efficiency increased by 7.4%,pressure is increased by 110 k Pa compared the original pump.