水泵进水池底部压力脉动特性试验

Experiment on Characteristics of Pressure Fluctuation at Bottom of Pumping Suction Passage

为了研究泵站进水池中喇叭管下方漩涡产生的机理,探索进水池底部喇叭管下方水流压力脉动与漩涡产生的关系,在进水池底部喇叭管口下方布置20个压力脉动监测点,在转速2 200 r/min时进行了多个不同工况点的压力脉动试验。通过对水流压力脉动的时域特性、频域特性及进水池底部喇叭管下方的压力分布进行分析,揭示了轴流泵喇叭管下方水流压力脉动的规律及压力分布与漩涡之间的关系。进水池底部压力脉动的主频是叶轮转频的2倍,说明轴流泵进水池底部喇叭管下方水流的压力脉动仍然受到叶轮旋转的影响;大流量工况下,喇叭管下方容易产生漩涡,且发生频率高,持续时间长,主要集中在喇叭管下方右前方的位置;小流量工况下,喇叭管下方也能产生漩涡,但发生频率低,持续时间短,主要集中在喇叭管内部正前方的位置。在不同工况下发生漩涡的位置与进水池底部喇叭管下方低压区位置相对应。

In order to study the mechanism of bottom vortex generation in the suction passage of pumping station,and explore the relationship between pressure pulsation and vortex generation under flare pipe at bottom of suction passage,20 pressure pulsation monitoring points were evenly arranged at the bottom of suction passage in the form of concentric circular ring. At speed of 2 200 r/min,the pressure pulsations experiment under different flow conditions was done. By analyzing the time domain and frequency domain of pressure fluctuation and pressure distribution at the bottom of suction passage,the law of pressure pulsation at the bottom of suction passage of the axial flow pump was revealed. According to the analysis of pressure fluctuation time domain,the pressure fluctuation amplitude of the bottom water flow at the bottom of inlet basin was decreased and then increased with the increase of flow rate. The maximum pressure of the flow pressure was fluctuated under the large flow condition,which was the same as the design flow. No vortex and whirlpool occurred mainly in the case of large flow conditions. The experimental results showed that the pressure pulsation at the bottom of the suction passage was twice as high as that of the impeller,and there was no dominant frequency at impeller frequency,which indicated that the pressure pulsation at the bottom of the suction passage under the bell-tube of the axial flow pump was still affected by impeller rotation. Under large flow conditions,the vortex under the bell-tube was easy to produce with high frequency of occurrence and long duration. The position of the vortex under different working conditions was corresponded to the position of the low pressure zone at the bottom of suction below the bell-tube.