零流量工况下立式离心泵振动特性试验研究

Experimental Study on Vibration Characteristics of a Vertical Centrifugal Pump Under Zero Flow Condition

离心泵在启动时一般为关阀启动,即为零流量工况。立式离心泵在长距离调水和大型灌溉工程中应用日益广泛。为探究立式离心泵零流量工况下振动特性,在水泵底座布置了1个三向振动传感器,在水泵进、出口法兰盘顶部各布置1个轴向振动传感器以及在水泵出口管道顶部布置1个压力脉动传感器,测试了零流量工况下额定转速(1.0 nr)以及1.2 nr、0.8 nr、0.6 nr、0.4 nr等5个不同转速下的水泵振动和压力脉动。结果表明:零流量工况下立式离心泵进口轴向、出口轴向和底座轴向上的振动均较大;升速至1.2倍额定转速,底座轴向上的振动强度增至额定转速振动强度的1.6倍,降速至0.8倍额定转速,振动强度降至额定转速振动强度的1/4倍,降低转速启动,能大幅度降低水泵的振动强度;叶片频率是水泵进口、出口和底座轴向方向振动的主要频率,压力脉动是零流量工况下立式离心泵振动的一个重要激励源。研究结果可为同类大型立式离心泵的设计以及泵站建成后的运行管理提供参考。

The centrifugal pump is generally started with the valve closed when starting,that is,zero flow condition.Vertical centrifugal pumps are widely used in long-distance water transfer and large-scale irrigation projects.In order to investigate the vibration characteristics of a vertical centrifugal pump under zero flow condition,a three-direction vibration sensor is arranged on the base of the pump;an axial vibration sensor is arranged on the top of the inlet and outlet flanges of the pump;a pressure fluctuation sensor is arranged on the top of the outlet pipe of the pump.The vibration and pressure fluctuation of the pump at rated speed(1.0 nr),1.2 nr,0.8 nr,0.6 nr and 0.4 nr were tested.The results show that:the inlet axial,outlet axial and base axial vibration of the vertical centrifugal pump are larger under zero flow condition.When the speed is increased to 1.2 times of the rated speed,the vibration strength of the base axis is increased to 1.6 times of that at the rated speed,and when the speed is reduced to 0.8 times of the rated speed,the vibration strength is reduced to 1/4 times of that at the rated speed.When the speed is reduced,the vibration strength of the pump can be greatly reduced.Blade frequency is the main frequency of pump inlet,outlet and base axial vibration,and pressure fluctuation is an important excitation source for vibration of vertical centrifugal pump under zero flow condition.This paper can provide reference for the design of similar large vertical centrifugal pump and the operation management of the pump station after completion.