带可调式前置导叶轴流泵空化性能试验

Experiment on Cavitation Performance of Axial Pump with Adjustable Inlet Guide Vanes

以一台带可调式前置导叶轴流泵为研究对象,在闭式试验台上进行了非额定工况的空化性能试验,揭示了前置导叶对轴流泵空化性能及进出口压力脉动的影响。空化性能曲线表明:安装前置导叶后,水力损失增加,扬程下降,但临界汽蚀余量减小,空化性能得到改善;前置导叶由负角度向正角度调节时,虽然扬程逐渐降低,但抗汽蚀性能得到增强。压力脉动分析结果表明:空化初生时,设置前置导叶后进出口压力脉动幅值均增加,且峰值主要出现在叶频及其谐频处,临界空化与空化严重时,进口压力脉动主要集中在低频处,出口则呈现宽频脉动特性;流量降低时,泵内流态紊乱,前置导叶对压力脉动幅值影响较小,且脉动峰值出现位置随前置导叶角度变化而改变。

In order to reveal the influences of variable inlet guide vanes （IGVs） on cavitation performance of axial pump under off-design conditions, experiment was conducted in a closed test rig at the Pump Station Laboratory of Wuhan University. Both the operating conditions with and without IGVs and the situations when the angles of IGVs were changed were researched. The angles of IGVs were adjusted by bolts. The cavitation performances were obtained and the unsteady pressure pulsations collected by pressure sensors which installed in pump inlet and outlet were analyzed based on fast Fourier transform. The results showed that when the pump device was assembled with IGVs, pump head was reduced due to more energy losses were induced. However, the cavitation performance was improved. At the same time, the critical net positive suction head was decreased and the cavitation performance was enhanced as the angles of IGVs were adjusted from negative to positive values. The pressure＂ pulsation results showed that when cavitation occurred, pressure amplitude was magnified both in pump inlet and outlet when IGVs were set up, and the pressure peak appeared mainly in blade frequency and its harmonic frequencies as a result of the influence of rotating of impeller. With the development of cavitation, pressure pulsation aggregated in low frequency in inlet and appeared broadband feature in outlet. When mass flow rate was decreased, the pressure amplitude discrepancy shrank and the pressure peak depended on the angles of IGVs.