Abstract: Oil-gas mixture transport is a crucial technology in the crude petroleum and natural gas industry. A rotodynamic multiphase pump has the advantages of compact structure, wide operation range, and good abrasion resistance. In a single-stage rotodynamic multiphase pump, the relationship of the radial forces on the impeller and guide vaneswith its gas-phase flow patterns were investigated numerical simulations under inflow gas volume fractions (IGVFs) of 0%, 5%, 10% and 15%. The centers of the radial forces were found to be located at the coordinate origin under the single liquid phase inlet condition, and their eccentricity increased with the increasing IGVF values. Dominant frequencies of these forces were related to impeller rotational frequency and blade number, and the amplitudes were found to increase with the increasing IGVF values. Distribution of fluid fraction over each impeller passage was non-uniform, and most of the gas was accumulated around the hub. Strip-shaped gas zones generated at the trailing edges of the impeller blades entered guide vane channels and developed into gas pockets, and the developing time was related to the dominant frequencies of radial forces. Phase differences in gas volume flow rates occured among different impeller passages, resulting in unequal gas volumes over these passages. This led to uneven forces on each blade and a radial force on the impeller. With the value of IGVF increasing, the developing period of the gas pockets became shorter and the dominant frequencies increased.

Key words: multiphase pump, radial force, gas volume fraction, gas flow pattern, correlation