泵作透平尾水管压力脉动特性分析与试验

Analysis and experimental investigation of pressure fluctuation in draft tube of pump as turbine

为研究泵作透平尾水管压力脉动特性及内部流动机理,采用试验与雷诺时均非定常数值计算相结合的方法,对尾水管内部压力脉动及其上游过流部件对其内部流动特征的影响进行分析,得到不同位置监测点处的压力脉动特征。研究结果表明:蜗壳内压力脉动主频为叶片通过频率,动静干涉作用是引起透平蜗壳内压力脉动的主要原因;由于上游蜗壳内产生的压力脉动传播到叶轮导致叶轮流道内除主频轴频外还存在1个次主频叶频;小流量时尾水管中心区域出现回流现象,但是随着流量的继续增加回流现象逐渐消失;透平尾水管内压力脉动主要为上游蜗壳内压力脉动传播所致,动静干涉作用是其产生的主要原因;随着流量的增加,透平内部压力脉动主频幅值增加,且大流量工况下达到最大值。

To study the pressure fluctuation characteristics and internal flow mechanism of draft tube, the pressure fluctuation in draft tube and the effect of upstream flow passages were studied using an experiment in combination with numerical calculation method. The pressure fluctuations at different monitoring locations were analyzed. The results show that the blade passing frequency dominates the pressure fluctuations in the volute, and it is mainly caused by rotor-stator interaction. For propagation from volute to impeller domain, besides the dominant frequency of shaft frequency of pressure fluctuation, there is another subprimary frequency of blade passing frequency in the impeller. Near the center region of draft tube, backflow phenomenon appears in low flow rates. But the backflow disappears with the increase of flow. The pressure fluctuation of draft tube is caused by the volute. With the increase of flow rates, the amplitude of dominant frequency inside the pump as turbine increases, and the maximum value is attained under high flow rates.