混流泵起动过程转子轴心轨迹的试验研究

混流泵起动过程中的振动失稳严重威胁着泵机组的安全,研究起动过程中的轴心轨迹,可以全面、直观地反映瞬态效应对机组运行稳定性的影响,掌握非调节工况下转子的振动状态。基于本特利408数据采集系统,测量获得了起动加速过程中不同转速下转子的轴心轨迹图和时域图,分解提纯一倍频和二倍频轴心轨迹图及其时域图,解析起动过程不同转速下的频谱图。研究结果表明,加速过程中,一倍频轴心轨迹由长短轴相差不大的椭圆逐渐变为圆形,可以判断转子存在弓状回转涡动且涡动不断加剧;二倍频轴心轨迹由近似水平线段逐渐变化为水平方向扁平的椭圆,可以判断转子存在不对中现象且水平方向的振动不断加剧。结合瞬态外特性曲线,研究发现随着转速的逐渐增大,转子系统的瞬时水力冲击逐渐增大,转子不平衡量和径向偏移量逐渐增大,振动情况逐渐加重,当转速达到最大值时,轴系振动出现一个峰值并随转速稳定有所降低并逐渐趋于稳定。加速是引起轴系振动的主要原因,瞬态效应是影响振动故障恶化的重要因素。研究成果对于实时评估混流泵起动过程中的轴系运行状态、有效降低或防止振动故障的恶化具有重要的工程应用价值和理论指导作用。

Experimental Study on Orbit of Shaft Centerline of Mixed-flow Pump during Starting Period

The vibration instability during the startup process of mixed flow pump seriously threatens the safety of the pump unit,and through the research of the orbit of shaft centerline,it can comprehensively and visually reflect the transient effect on the stability of unit operation and hold the vibration state of rotor under abnormal operation condition.Based on the Bentley 408 data acquisition system,it obtained the rotor axis locus chart and time domain chart during starting process under different rotational speed,and purified its the rotor axis locus chart and time domain chart of the 1X and 2X frequency,and analyzed the spectrum diagram under different rotating speed.The research results show that,during the startup process,the orbit of shaft centerline chart of the 1X frequency is from a ellipse which long axis and short axis is similar gradually into a circle,and it can judge that the rotor has arcuate rotating vortex and the vortex is increasing;the orbit of shaft centerline chart of the 2X frequency is from similiar horizontal line segment gradually into a horizontal flat ellipse,and it can judge that the rotor has eccentric phenomena and the horizontal vibration is increasing.Connect to the transient external characteristic curve,the study found that as the speed increases gradually,and the rotor system transient hydraulic load increases gradually,and the rotor imbalance and radial offset increases gradually,and the vibration situation gradually aggravate,when the speed reach maximum,a peak is coming in shafting vibration and with the speed tends to stability it decreases and gradually becomes stabilized.Acceleration is the main cause of shafting vibration,and transient effects are the important factors influencing the deterioration of vibration.The research results for the real time assessment of shaft system operation state during the startup process of mixed flow pump,and for reducing or preventing the deterioration of vibration effectively has important value of engineering application and theory instruction function.