Effect of the Discharge Piping Scheme on the Pressure Fluctuations Induced from A Laboratory Pump

Fluid-dynamic noise induced by the unsteady fluid phenomena usually causes a negative influence on the hydraulic circuit system during the pump operation, especially at off-design flow rates. The spectrum of the pressure signals measured directly in the pipeline of the pump is usually employed to reflect the acoustic characteristic parameters of the fluid-dynamic noise of the pump itself. However, there exists a large difference between the spectrum characteristics directly measured and the actual characteristics of the acoustic source inside the pump due to the effects of the acoustic properties of the piping. Therefore, in order to verify the effect of the discharge piping on the pressure fluctuations of a laboratory pump, three different discharge piping schemes connected to the pump outlet were studied by opening and closing different valves. The results showed that the amplitude of the pressure pulsations in a constant monitor point changed with the shaft frequency and blade passing frequency. The variation range of the pressure pulsation magnitudes for the points monitored at the pump outlet is evidently larger than that for the points close to the cutwater of the volute