不同空化条件下轴流泵反向发电压力脉动特性研究

以南水北调某泵站为模型, 对该泵站大型轴流泵反向发电发生空化条件现象进行全流道数值模拟。对反向发 电工况下空化现象进行定常与非定常研究, 并与试验结果做比较, 得出了水泵反向发电时发生不同空化条件下的气 泡体积分布规律, 并预测了叶片发生空化的发展特性。在反向发电工况下对三个监测面的压力脉动进行研究, 得出 压力脉动幅值在导叶进口处最小, 转轮出口处幅值最大, 约为转轮进口处 7 倍, 水流受转轮转动影响严重, 主频为转 频。不同空化数下转轮前后的压力脉动幅值随着空化系数减小而增大, 压力脉动主频不受空化系数影响。空化数 越小, 叶片受到的径向力减小, 轴向力增加, 加剧转轮的不稳定性。为确保轴流泵反向发电运行的稳定与高效, 应使 得装置在较高的空化系数下运行。 Taking a pumping station of South2to2North Water Transfer Project as a model, we conducted full2channel numerical simula2 tion of the cav itation conditions of large2scale axial flow pumps in the pumping station during reverse power gener ation. We studied the steady and unsteady cavitation phenomena under the condition of reverse pow er generatio n, and compared the ex perimental results. We obtained the bubble vo lume distribution law under different cavitation co nditions, and predicted the development characteristics of blade cavitation. The pressure fluctuation of the three mo nitoring surfaces was studied under the condit ion o f r everse power g ener ation. The r esults showed that the pressur e fluctuatio n amplit ude w as the smallest at the g uide blade inlet and the lar gest at the runner outlet, which w as about 7 times of that at the runner inlet. The wat er flow was serio usly affected by the r unner ro tation and the main frequency was the frequency of t he runner. The amplit ude of pressur e fluctuatio n before and after the r unner wo uld in2 cr ease w ith t he decr ease of the cavitation co efficient under differ ent cavitat ion numbers, and the main frequency of pr essure fluc2 tuatio n w as not affected by the cavitation co efficient. T he sma ller t he cav itation number, the less the r adial fo rce o f the blade, the gr eat er the axial force, incr easing the instability o f the runner. To ensur e the stable and efficient operat ion of the axial flow pump in reverser power generation, the dev ice sho uld be running under a hig h cav itation co efficient. 国家自然科学基金( 51579080)