An Analysis of the Hydraulic Characteristics of Different Impellers in Axial-flow Pump Devices

In order to study the hydraulic performance of different impellers in the same pump device,two pairs of axial-flow impellers with similar performance are selected based on a vertical pump device. The flow conditions of two pairs of impellers in the same pump device are analyzed by numerical simulation method,and the external characteristics of the pump device are tested by the model test. According to the results of numerical simulation model test,the pressure distribution on the surface of two impeller blades under the same head is compared.The pressure pulsation values at different measuring points and the flow velocity vector diagrams inside the impeller guide vane are compared under multiple working conditions,the influence of impeller on other flow parts is also analyzed. The numerical simulation results show that to meet the design requirements,different impeller running conditions are different. Under the corresponding design conditions,the pressure distribution on the blade surface of the two impellers is obviously different. The pressure difference at the blade head is the reason for the large amplitude of pressure pulsation at the impeller inlet,the vortex in the guide vane blade leads to the prominent low-frequency pressure pulsation in the guide vane blade,the velocity distribution inhomogeneity of guide vane outlet is consistent with the hydraulic loss of outlet passage.The model test results show that the pump efficiency of the two impellers is basically the same,but the cavitation performance is different. The numerical simulation results agree well with the model test results,which verify the reliability of the numerical simulation.