Research On The Flow Characteristics And Energy Conversion Of Helical-Axial Multiphase Pump When Transporting Crude

With the development of economy,China’s demand is growing for oil.In recent years,China began to explore the deep-sea oil in order to meet the oil crisis.In the process of deep-sea oil exploitation,oil and gas mixed transport technology has played a key role.Helical-Axial Multiphase Pump has the dual role of pump and compressor.So it is more suitable for the transport of gas-liquid two-phase flow.Helical-Axial Multiphase Pump is easy to occur failure phenomenon during practical engineering applications,the main reason is that the non-synchronicity of the gas-liquid two-phase will cause the gas-liquid separation in the pump,it will lead to cavitation and steam blocking phenomenon.In previous studies,Helical-Axial Multiphase Pump is basically studied through water.However,the pump does not transport water in practical engineering applications.The crude with high viscosity and complex composition,so it is inevitable to have errors in studying its performance through water.In this paper,Helical-Axial Multiphase Pump is numerically simulated through water and crude,reseach the flow characteristics and boost capacity of impeller domain of Helical-Axial Multiphase Pump under different medium viscosity and inlet gas volume fraction(IGVF).The Euler-Euler model and the standard k-ε model are used in the numerical simulation to study the flow characteristics and the power capacity of impeller domain of Helical-Axial Multiphase Pump.Firstly,the performance of Helical-Axial Multiphase Pump is analyzed under different viscosity and IGVF.Finally,it is found that with the increasing of IGVF and viscosity,the head and efficiency of Helical-Axial Multiphase Pump gradually decreases,and the pump performance is obviously affected.At the same time,the pressure,GVF and turbulent kinetic energy are studied for Helical-Axial Multiphase Pump under different viscosity and IGVF.The results show that with the increasing of viscosity,the change range of the GVF is smaller from impeller to diffuser,and the change of GVF is the most obvious in diffuser.And the working face of impeller and diffuser and the back blade are also decreasing.Then the pressure is analyzed,with the increasing of viscosity,the inlet pressure of impeller increases gradually while outlet pressure change diffuser is not very obvious.As can be seen from the blade expansion diagram of impeller and diffuser,the pressure at the inlet of diffuser blade is also gradually increasing.Finally,the turbulent kinetic energy is studied in Helical-Axial Multiphase Pump.The results show that with the increasing of viscosity,the turbulent kinetic energy in Helical-Axial Multiphase Pump increases gradually,which is most obvious in the hub and rim side,so it will cause greater loss in water.Secondly,the work of impeller is studied in the single stage Helical-Axial Multiphase Pump.The results show that the variation trend of static pressure,dynamic pressure,total pressure and static pressure energy is basically the same,which decreases first and then increases to a stable process.With the increasing of viscosity,variation trend of static pressure decreases gradually while dynamic pressure increases gradually in impeller.Moreover,IGVF has great influence on static pressure,but little influence on dynamic pressure.The change of viscosity also has a certain effect on the work capacity of impeller,mainly affecting the first half of impeller.With the increasing of viscosity,head of the first half of impeller decreases gradually,and has little influence on head of the second half.The work capacity of impeller is mainly concentrated in the first half,so with the increasing of viscosity,the work capacity of impeller gradually decreases.Finally,the working of impeller is studied in the two-stage and three-stage Helical-Axial Multiphase Pump.The results show that the dynamic pressure,static pressure,total pressure and head have the same variation trend,and IGVF still has a slightly greater influence on the static pressure,but a little influence on the dynamic pressure.The viscosity is increasing,the trend of static pressure decreases gradually,while the trend of dynamic pressure increases gradually.By studying the head difference of each impeller,the results show that the work capacity of each impeller decreases with the increasing of viscosity.And through the comparison,it is found that power of the first stage impeller is the strongest,the power of the second and the last stage impeller is weak.