叶轮口环间隙对离心泵性能和振动影响的试验研究

Experimental Research on the Effects of Wear-ring Clearance on the Performance and Vibration Characteristics of Centrifugal Pumps

为探究离心泵的性能和振动的变化情况,在闭路试验台上对7对等间距变化的口环间隙进行试验,试验数据表明,随着口环间隙的增加,同流量下的扬程下降,扬程流量曲线的峰值在变小;在低流量区,口环间隙的增加导致功率的升高,在高流量工作区,功率趋于一致;通过不同口环间隙下振动的功率谱对比,发现由回流冲击引起的0.5 Hz处的振动与口环间隙有关,而且由于回流对前、后口环振动响应并不同步,0.5 Hz处峰值并非单调变化;间隙改变叶轮盖板上的静压分布引起轴向力的变化,导致210 Hz处的轴频振动强度的起伏;在叶轮转频对应于功率谱280 Hz处的峰值随着间隙增加,呈下降趋势;流体振动带来的300~500 Hz处的多个谱峰,随间隙增加,振动能量逐渐往高频移动。

The experiment was carried out for the clearances of 7 pairs of wear rings which vary at equal space in a closed loop test bench to investigate the change of the performance and vibration characteristics of centrifugal pumps.The test data shows that,as the wear ring clearance increases,the delivery lift at the same flowrate decreases,and the peak value of the head versus discharge curve decreases.The increase of the wear ring clearance caused power rise at the same small flow rate,but the power remained constant at the same high flow rate.By comparing the vibratory power spectrum at different clearance of the wear ring,it was found that the vibration at 0.5 Hz caused by recirculation flow impact was related to the clearance of the wear ring,and the peak value at 0.5 Hz did not change monotonously due to asynchronous vibration response of the recirculation to the front and back wear rings.Meanwhile,the clearance changes static pressure distribution on the coverplate of impeller,which causes change of axial force,and results in the fluctuation of shaft frequency vibration intensity at 210 Hz.The peak value of the impeller rotating frequency corresponding to 280 Hz of the power spectrum decreased with the increase of the clearance.For multiple spectrum peaks brought by fluid vibration at 300Hz to 500 Hz,the vibration energy gradually moves to higher frequency.