高扬程离心泵振动特性的试验研究

针对一台小流量高扬程离心泵组,通过调节流量和转速等手段对离心泵进行变工况振动测试研究,分析了泵组振动的基本特性,探讨了与泵组振动相关的内部流动形态,并借助泵组出口旁通阀进行分流抑制泵组振动测试研究,研究了系统小流量运行工况下控制泵组振动水平的方法.测试及研究结果表明:随着流量的增大,泵组总振级呈先减小后增大趋势,设计流量下泵组总振级最低,相比关死点工况,总振级低约9 dB,且尤其体现在1倍叶频和1.5~3 kHz宽频段,这主要与泵组不同流量下内部流动激励有关;泵组总振级随转速的增大呈增大趋势,且在1倍轴频和低频10~315 Hz范围内振级影响更显著;泵组振动强度随旁通流量的增大呈先减小后保持稳定的趋势,最佳旁通流量下总振级降低约2 dB,这说明对于系统要求在小流量工况运行的泵组,可通过合理控制旁通流量有效缓解和控制离心泵组振动.

Experiment on vibration characteristics of centrifugal pump with high head

The vibration characteristics of a centrifugal pump with low specific-speed were measured when it was operated at various conditions including different flow rates and rotational speeds and so on. The characteristics of vibration in the pump was analyzed,its internal flow patterns that was related to the characteristics were discussed. The vibration was measured as well when a bypass valve was installed in the pump to explore the method for reducing pump vibration levels when it was working at a low flow rate. It was shown that the pump vibration achieves a minimum level at the design point.Compared with the shut-off condition,the minimum level is lowered by 9 dB,especially for the blade passing frequency and the frequency in the range of 1. 5-3 kHz. At off-design conditions,however,the vibration level is increased. This phenomenon is obviously related to the excitation of internal flow at different flow rates. With increasing rotational speed,the overall vibration level rises,especially for the shaft rotational frequency and the low frequency in the range of 10-315 Hz. With increasing bypass flow rate,the pump vibration level decreases steadily until a constant level is reached. Note that the overall vibration level is reduced by 2 dB at the best bypass flow rate,suggesting a properly controlled bypass flow rate can suppress pump vibration level effectively when the pump is operated at a low flow rate.