多工况下高水头水泵水轮机压力脉动特性分析

Analysis of Pressure Fluctuation of High-head Pump Turbine under Various Operation Conditions

为研究多工况下高水头水泵水轮机内部的压力脉动特性,以某抽水蓄能电站水泵水轮机模型为例,采用SST湍流模型对非设计工况点下的水泵水轮机进行三维全流道非定常数值模拟,同时监测了固定导叶与活动导叶间、无叶区及尾水管处的压力脉动。结果表明,对于固定导叶与活动导叶之间的区域,水轮机工况下的压力脉动主频为叶片通过频率,而水泵工况下的最高扬程和最低扬程工况的主频分别为转频和叶片数通过的频率;对于无叶区,由于受到强烈的动静干涉效应,水轮机、水泵工况下的主频均为转轮叶片数通过频率,且脉动幅值较大;对于尾水管区域,直锥段处的频率分布规律与流量有关,水轮机小流量工况下,尾水管内主要为0.3倍转频的低频压力脉动,而水轮机大流量工况下,脉动频率主要以2.6倍转频为主。

In order to study the characteristics of pressure pulsation in high-head pump turbine under various operation conditions, taking model pump turbine of a pumped storage power station as an example, the three-dimensional unsteady flow in the whole passage of the pump-turbine was conducted by using SST turbulence model under non-design conditions. And then, the pressure fluctuation between fixed guide vane and movable guide vane, no-blade zone and draft tube were monitored. The results show that for the area between fixed guide vane and movable guide vane, the dominant frequency of the turbine operating mode is blade passing frequency, while the dominant frequency of the pump operating mode at the highest and lowest head is runner rotational frequency and blades passing frequency respectively;For the no-blade region, the dominant frequencies of turbine and pump operating mode are runner blades passing frequency and the frequency of harmonics, and the fluctuation amplitude is larger;For the draft tube region, the frequency distribution at the straight cone section is related to the flow rate;Under the small flow rate of turbine mode, there is mainly low-frequency pressure pulsation with 0.3 times runner rotational frequency in the draft tube, while under the large flow rate of turbine mode, there is mainly 2.6 times runner rotational frequency in the draft tube.