不同空化工况下轴流泵装置压力脉动试验

为研究不同空化工况下轴流泵装置内部压力脉动特性,采用动态压力传感器对派河口泵站轴流泵装置模型的叶轮进口、叶轮出口、导叶出口3个压力监测点,分别在2.5、3.5、4.5、5.4m扬程和未发生空化、临界空化（泵装置效率下降1%）、深度空化（泵装置效率下降3%）等12种工况下进行了压力脉动试验。试验结果表明：叶轮进口处的压力脉动曲线为平滑的近似正弦曲线;叶轮出口处压力脉动曲线幅值最大,且只在高扬程、未发生空化工况下的一个旋转周期内表现出明显有规律的二次谐波特性;导叶出口的压力脉动时域特性与叶轮进口相似。快速傅里叶变换(FFT)结果表明：各监测点在各工况下的主频为叶片通过频率的整数倍频,同一扬程工况下,随着空化程度的加深,各监测点主频附近的谐频逐渐向低频段移动;导叶出口与叶轮进口受叶频影响较小,且表现出相似的频率特性。

Experiment on Pressure Fluctuation of Axial Flow Pump System under Different Cavitation Conditions

In order to obtain the pressure pulsation characteristics of the model of one axial flow pump unit named Paihekou station under different cavitation conditions, the monitoring points of pressure were set near the impeller inlet, the impeller outlet and the vane outlet, the test was conducted by applying a dynamic pressure sensor system under four different head conditions with three different cavitation conditions of no cavitation, critical cavitation (pump efficiency decreased by 1%), deep cavitation (pump efficiency decreased by 3%). The test results showed that the pressure pulsation curve at the inlet of the wheel was a smooth and approximate sine curve, and the amplitude of the pressure fluctuation curve at the outlet of the impeller was the largest and showed obvious second harmonic characteristics in a rotating cycle under the high head condition without cavitation. The time domain characteristics of pressure pulsation of vane outlet were similar to that of impeller inlet. The results of FFT showed that the main frequency of each monitoring point under different working conditions was the integral frequency doubling of the blade passing frequency. With the deepening of cavitation, harmonic frequency near the main frequency of each monitoring point was gradually moved to the low frequency section. The vane outlet and impeller inlet were less affected by the blade passing frequency and showed similar frequency characteristics.