Influence of the inlet vortex on axial flow pump unit

Abstract

Starting from the view on the influence of inlet vortex on the pressure pulsation in axial flow pump, the influence mechanism of inlet vortex on axial flow pump was investigated by the pressure fluctuation test. The pressure pulsation sensors are installed at the impeller inlet and the impeller outlet and the guide vane outlet. The pressure fluctuation test was carried out and the development process of the inlet vortex was clearly captured by the high speed camera. The results show that the amplitude of pressure pulsation under the small flow rate conditions is the largest at the same position of axial flow pump, and the amplitude of the pressure pulsation decreases gradually with the increase of flow rate. With the accumulation of rotational energy increasing more than dissipation and the suitable space and sufficient time, the inlet vortex occurs in the pump sump. The pressure pulsation excitation source in impeller inlet is the rotation of the impeller. And the pressure pulsation in the impeller inlet is influenced by the vortex. The pressure pulsation in the impeller outlet is induced by the rotor-stator interaction between the guide vane and the impeller. The pressure pulsation in the vane outlet is mainly influenced by the outlet circulation. Under the large flow rate conditions, the inlet vortex developed into the impeller, increasing the instability of the flow field inside the impeller and affecting the pressure pulsation interior the impeller, decreasing the unit vibration and hydraulic performance, causing the vibration of the pump unit.