The characteristics of the transient rotational speed of centrifugal pumps are of great significance for pump state recognition as it is closely related to the internal flow and the state of operating centrifugal pumps.In order to investigate the characteristics of the transient rotational speed of centrifugal pumps,the transient speed of a single-stage single-suction centrifugal pump (type IS-65-50-160) was measured precisely by an encoder with the utilization of virtual instrument technology.Furthermore,a time-frequency characteristic spectrum of the transient rotating speed under different operation conditions was established and analyzed.The results show that the speed of the centrifugal pumps decreases turbulently with the increasing of flow rate.Under design conditions,the speed also fluctuate by about 20 r/min.In addition,the fluctuation is periodic and the rotating frequency of the impeller plays a dominant role in the speed fluctuation under both design and off-design conditions.The RMS of the speed fluctuation and the amplitude of the dominant frequency become higher with the increasing of flow rate.%转速是旋转机械运行的重要特征之一,离心泵转速的瞬变特征能够很好地反映离心泵内部流动特征及其运行状态,对离心泵的运行状态识别具有十分重要的意义.为了探究离心泵转速的瞬态特性,基于虚拟仪器技术,通过轴编码器对IS-65-50-160型单级单吸离心泵的转速进行了精确测量,通过编写Labview程序对试验数据进行采集,建立不同工况下转速的时频特征谱.分析结果表明:离心泵的转速随着载荷的增大呈现波动下降的趋势;在各个工况下,离心泵的转速均存在一定程度的波动,在设计工况下其转速变化可达21 r/min;转速波动存在一定的周期性,泵转动的轴频是转速波动的主频,且频率主要集中在轴频及轴频以下的低频处;转速波动的RMS值及主频处的振幅值均随着流量的增加而呈上升的趋势.
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