Effect of Virtual Mass Force on the Mixed Transport Process in a Multiphase Rotodynamic Pump

To explore the effect of virtual mass force, the unsteady two-phase flow in a multiphase rotodynamic pump impeller was numerically simulated, where the inlet gas void fraction was 4.9%, 14.9%, and 25.2%, respectively. The drag force and the virtual mass force were accounted for and the cases with and without the latter one were both analyzed for comparison. The results show that the trajectories of the gas bubbles are influenced by the virtual mass force evidently in the inlet extended region. Due to the effect of virtual mass force, some gas will firstly move to the shroud before accumulating in the hub region of the impeller. The characteristic of the pump head was discussed and the results demonstrate that the virtual mass force can decrease the pump head and lead to its fluctuation. In addition, the comparison between the steady and unsteady simulation shows that the virtual mass effect can be found only by unsteady simulation.