Influence of the balance hole on the performance of a gas-liquid two-phase centrifugal pump

Centrifugal pumps are prone to vibration due to unstable impeller forces under gas-liquid two-phase conditions. The balance hole can balance the axial force on the impeller and improve the operation stability of the pump. In this study, the influence of the balance hole on the performance of the multiphase pump is studied. By parameterizing the balance hole, the influences of the radial position, circumferential position and diameter of the balance hole on the external characteristics, gas-phase distribution and axial force of the multiphase pump are investigated. Results show that the balance hole degrades the centrifugal pump performance at small gas volume fraction (GVF). At high GVF, when the balance hole is located in the gas phase accumulation zone and the diameter is above 6 mm, the performance of the centrifugal pump will be improved. The balance hole can improve the distribution of gas-phase in the impeller, but the effect is limited to the local area around the balance hole. The effect of the balance hole on the axial force weakens as the centre position of the balance hole moves from the impeller inlet to the impeller outlet, increases with increased hole diameter and is less influenced by circumferential position.