Numerical investigation on a double suction twin-screw multiphase pump

Based on the dynamic mesh technology, the moving grids of the double-suction screw multiphase pump were generated by the software SCORG. Then the three-dimensional transient simulation model was established to investigate the two-phase flow mechanism inside the screw pump under different inlet gas volume fraction (IGVF). The results show that the pressure inside the working chamber increases step by step from inlet to outlet and is symmetrical. The pressure drops sharply at the inlet of circumferential clearance and then decrease linearly in the clearance. The curved flow in suction and discharge flow passage causes the gas separation and high gas volume fraction (GVF) area in suction and discharge chamber. Four vortices in cross section of discharge pipe cause four high GVF areas due to the centrifugal force produced by the vortices. The high GVF areas scatter in working chambers and change slightly with the rotation angle except the last chamber under the IGVF 10%. The two-phase leakage flow shows layered flow where the gas concentrates at the bottom of the gap. Thus, the high GVF areas on the surface of the rotors mainly exist at the position of gaps. The work will provide instructions for improving its performance under high IGVF.