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抽水蓄能电站工况转换频繁,过渡过程中水泵水轮机可历经全特性4个象限,不稳定的复杂流动演变使过渡过程中事故频发。本文针对某低比转速模型水泵水轮机进行四象限全流道数值计算,得到同一开度下水轮机内部流态的演变规律。结果显示,在水泵区部分负荷工况,导叶区产生旋转失速现象,失速区的个数随流量大小变化;失速涡阻塞流道,使局部压力升高,产生周向传播的低频压力波动。在水泵制动区,当转速较高时,离心力作用使得水流不能均匀进入转轮,在转轮内产生旋转失速现象。在水轮机反“S”区,转轮进口产生的回流漩涡结构随流量在某些工况点的突变,导致沿转轮进口展向的流速分布呈现随流量而突变的现象。入流分布在飞逸点附近的突变使水流对转轮的做功特性发生突然变化,可能是导致空载不稳定的原因。
Pumped storage power station conditions change frequently, during the transition process, pump turbines may experience four quadrants of full-featured, unstable and complex flow evolution so that the transition process of frequent accidents. In this paper, a four-quadrant full-flow numerical calculation is carried out for a pump with a low specific speed and the evolution of the flow pattern inside the turbine is obtained. The results show that the rotating stall occurs in the guide vane zone under the partial load condition of the pump section, and the number of stalling zones varies with the flow rate. The stall vortex blocks the flow channel, causing the local pressure to rise, resulting in the low frequency pressure fluctuation in the circumferential direction. In the pump braking zone, when the speed is high, the centrifugal force makes the water flow can not enter the runner uniformly, resulting in a rotating stall in the runner. In the “” “S ” area of the turbine, the sudden change of the return vortex structure generated by the inlet of the rotor with the flow at certain working conditions results in the phenomenon that the flow velocity along the inlet of the rotor changes suddenly with the flow rate. The abrupt change in the inflow distribution near the fly-away point causes abrupt changes in the work characteristics of the runner due to the flow of water, which may be responsible for the instability of the no-load.