Effects of vane wrap angle on flow induced vibration and noise of centrifugal pumps

Abstract: In order to better understand the effects of vane wrap angle on flow induced vibration and noise of centrifugal pumps, a single grade end suction centrifugal pump is chosen as research object. The vane wrap angle was varied from 115° to 110°, 120°and 125°, while the volute and other geometric parameters were kept constant. The vibration and noise signal of the model pump were acquired via PXI-4472B dynamic data acquisition system developed by NI Company in United States and measured respectively by the 4 acceleration transducers MA352A60 made in the PBC Company in USA with a range of 5-70 kHz, and one hydrophone with a range of 50-70 kHz and a received sound pressure sensitivity of -204 dB. The hydrophone measure point was located in pump outlet pipe and the 4 acceleration transducers were placed on the suction flange a1, discharge flange a2, the pump casing a3 and the pump foot a4 respectively. Based on the pump testing system and the virtual instrument data acquisition system, the pump flow-induced vibration and noise testing system was established, which realized the synchronous collection of the pump characteristics and the vibration and noise signal. In addition, the system improved testing accuracy. On the centrifugal pump closed experimental rig, the performance characteristics (flow-head curves and flow-efficiency curves), the flow-induced vibration and noise signals of model pump with different vane wrap angle in the full flow range were measured and analyzed. Experimental results show that there was an optimal value of vane wrap angle for pump to obtain maximum efficiency under design condition, because the unsteady flow (take-off flow and vortex) decreased with the increase of vane wrap angle, but the blade length growth, friction loss increased. 115° was found as the optimal vane wrap angle for the model pump in this investigation. The vibration intensity of model pump with different vane wrap angle at four measurement points was nearly unchanged or with a little fluctuation under small flow condition and vibration intensity increased significantly under large flow condition. The influence of flow-induced vibration on pump casing a3 was larger, the low vibration intensity was observed in the pump with 125° vane wrap angle. With the increase of vane wrap angle, the variation tendency of vibration intensity for suction flange a1 and discharge flange a2 measure points are augment at first and then decrease, for pump casing a3 and pump foot a4 measure points were complicated, but they achieved the minimum when vane wrap angle was 125°; Noise signals concentrate in the range of 0-2500 Hz, the shaft frequency and the blade passing frequency were the main reason of discrete noise in model pump. Under different conditions, the shaft frequency peak of noise signal increased at first and then decreased with the increase of vane wrap angle, but the peak of blade passing frequency varied intricately. The research results are helpful for hydraulic optimization design of low vibration and low noise centrifugal pump.