Pressure Pulsations of the Blade Region in S-Shaped Shaft-Extension Tubular Pumping System

The three-dimensional unsteady numerical method is applied to investigate the pressure fluctuation of the S-shaft extension pumping system. Some monitor pointers are set at the key positions of blade region to capture the changing rules of the pressure pulsations, from which the data are collected through time-domain and spectrum analysis. The predicted head and efficiency were validated by the comparison with the tested results, and the comparison result shows that the unsteady flow characteristic of pumping system can be simulated by this method. The pulsating amplitude decreases gradually from blade tip to hub, under the condition of large flow rate for both the inlet and outlet of the impeller, in the way different from the smaller flow rate condition. Through adjusting the impeller rotation speed and the number of blades, the dominant frequency can be controlled. For the same monitor point at the impeller, as the flow coefficient is becoming larger, the pulsating amplitude decreases, in which case, it decreases firstly and then increases between the impeller and the guide vane, and the pulsating amplitude is smallest on the high efficiency condition. The rotation speed of impeller has little effect on the dominant frequency at the outlet of guide vane.