Research on energy recovery and gas–liquid separation characteristics in diffuser of Helico-Axial Multiphase Pump

An Euler two-fluid model and a Shear Strain Transports (SST) turbulence model were used to study the gas–liquid flow law in a diffuser of a Helico-Axial Multiphase Pump by building a bedstand in this paper and studied energy recovery and gas–liquid separation characteristics of the diffuser in the Helico-Axial Multiphase Pump at different stages. The results show that the pressurization capacity of an impeller decreases gradually when the increase in IGVF (inlet gas volume fraction), and static pressure drops slightly in a dynamtic–static interface. Energy recovery characteristics are more complex at medium and high IGVF in the diffuser. The pressure gradient change perpendicular to the flow direction is the main factor causing two-phase separation on the back surface of the diffuser. The gas–liquid separation is mainly caused by the pressure gradient difference perpendicular to the flow direction on the working surface of the diffuser under the low IGVF, while the pressure gradient difference in the two directions is jointly influenced by the pressure gradient difference at medium and high IGVF.