Effect Of Slit Blade Gap Parameters On Performance Of Helical Axial Flow Multiphase Pump

The efficient exploitation,processing and utilization of deep-sea oil is of great practical importance to the development of economy and society.As the core component of deep-sea oil extraction equipment,the spiral axial flow gas-liquid mixing pump has the advantages of simple structure and the ability to transport high gas content gas-liquid mixing medium,thus becoming the preferred pump type for deep-sea oil extraction.However,wh en the pump is transporting high gas content gas-liquid mixed media,the impeller flow channel occurs gas phase aggregation,resulting in a decrease in the efficiency of the mixed pump,so it is important to improve the gas phase aggregation phenomenon in the impeller flow channel of the mixed pump,for the safe and reliable operation of the mixed pump in the medium and high gas content.In this paper,the Eulerian multiphase flow model and the SST k-ωturbulence model are selected to numerically simulate t he spiral axial flow gas-liquid hybrid pump under different inlet gas content conditions to investigate the effect of inlet gas content on the performance of the hybrid pump.In this paper,the effect of different slit widths,locations and slit deflection angles on the external and internal flow characteristics of the hybrid pump is investigated by opening slits on the trailing edge of the hybrid pump blade with the reference of the passive control technology of slit diversion in the wind turbine blade,and the main findings are as follows:（1）gas-liquid mixed pump in the transport of gas-liquid mixed media,vane suction surface trailing edge near the hub of the gas phase aggregation degree with the inlet gas rate increases and increases,mixed pump effici ency is also declining;through the analysis of the internal flow field,found that the cause of the gas plugging phenomenon is the gas-liquid two-phase medium density difference is large,in the radial pressure gradient and the joint action of the axial r everse pressure gradient,the gas phase agglomeration and gas phase vortex group in the flow channel stagnation.（2）Inspired by the passive control technology of slit diversion in airfoil and wind turbine blades,this paper numerically calculates differen t combination schemes from three aspects of different slit widths（?）,positionsαand slit deflection anglesγ,and introduces dimensionless slit width coefficients,positions and defl ection angles for improving generalizability,and then analyzes the changes of its external and internal flow characteristics,and finds that the slit width coefficients₂=21.4%,slit positions₂=10%,dimensionless The efficiency of the mixed pump is the highest when the gap deflection angle is₄=0.3,and the efficiency of the mixed pump reaches 66.41%when the inlet gas content is 60%,with a growth rate of 3.38%compared to the base model.（3）The pressure field of different open-slit solutions is analyzed,and it is found that the mechanism of open-slit blade to improve the gas plugging phenomenon in the impeller runner is:the high-energy fluid at the pressure surface is injected into the suction surface to provide energy to the low-energy fluid at the suction surface,so as to overcome the constraint of the inverse pressure gradient and flow out of the impeller smoothly.After the adoption of open-slit vane,the radial pressure gradient in the la tter half of the impeller flow channel is also reduced to different degrees,which effectively suppresses the occurrence of gas-liquid separation phenomenon,reduces the degree of gas-phase aggregation at the trailing edge of the suction surface of the van e near the hub,improves the flow condition in the flow channel of the gas-liquid hybrid pump,and improves the conveying efficiency of the hybrid pump.