Abstract: This paper presented the numerical simulation of the two-phase flow in a gas-liquid mixed pump by applying a mixing model. The influence of setting balance holes on the internal flow, performance and axial force under different inlet gas holdups was examined. This study found that the runner axial force reduced significantly under various operating conditions after setting balance holes; high-pressure fluid flowing back from the balance system disturbed the internal flow state, and could destroy and entrain bubbles accumulated in the flow channels. Taking the influence on the performance and axial force into consideration, we found it feasible to balance the axial force by using the balance hole in case of low air content at inlet. The inlet and outlet pressure coefficients of the balance system decreased nonlinearly with the increase of specific area coefficient; an excessive hole diameter will lead to a loss of the pump’s effective volume. Therefore, the optimal diameter should be adopted in design. We further found the amplitude and pulsation of the axial force were relatively small when the balance holes were located on the suction surfaces of the runner blades. This study sheds light on the understanding of the multistage gas-liquid mixed pump modified with the balance hole and provides reference for the design and optimization of its axial force system.

Key words: numerical simulation, the gas-liquid mixed pump, balance hole, reflux chamber, axial force, pressure coefficient