Influence of operating parameters on the vortex structure in the main flow passage of the helico-axial multiphase pump

The flow is extremely complex within the main flow channel during the operation of the multiphase pump, resulting in constant changes in the vortex structure, disrupting the orderly flow of the existing flow field, and reducing the performance of the pump. Numerical calculations, supplemented by experimental verification, are used as the main method for investigating influencing factors that affect the vortex structure in the impeller passage of the pump, and vortex structure present on isosurfaces is selected based on Q criterion to study the evolution of vortex structures under different working conditions. Results indicate that the flow rate affects vortex structure generation on the suction side and trailing edge of the blade. With an increase in flow rate, the vortex becomes complete from fine broken structures. Speed has a greater influence on vortex structures in inlet and outlet areas: the higher the speed, the larger the vortex structure attached to the impeller leading edge. The vortex structure is separated from the blade surface at two-thirds of the impeller under gas–liquid two-phase working condition, with an increase in inlet gas void fraction, and the vortex structure expands to the center of impeller passage. Therefore, exploring evolutions of the vortex structure can provide a certain theoretical basis for improving the stability of multiphase pump internal flow.