Transition of amplitude–frequency characteristic in rotor–stator interaction of a pump-turbine with splitter blades

With the increase in the designed net head and output capacity, the operational stability of the pump turbine, which is the core component of a pumped storage power station, requires further investigation. The originality of the current research lies in the analysis of the pressure pulsation characteristics in the vaneless space of a pump-turbine runner designed with splitter blades. Under the designed net head and high-flow-rate conditions, the dominant frequency of the pressure pulsation in the vaneless space corresponds to half the total number of runner blades, 4fn. As the flow rate decreases, a blade-passing frequency of 8fn corresponding to the total number of runner blades was observed. Subsequently, the amplitude of 8fn increased, which gradually became the dominant frequency, whereas that of 4fn diminished. The contribution of current research is that the transition of the amplitude-frequency characteristic of the rotor-stator interaction of pump-turbine runners with splitter blades is revealed, which is significantly different from the analysis of equal-blade pump-turbines in the existing literature. For pumped storage power stations equipped with pump-turbine runners with splitter blades, it is necessary to consider the dominant frequency in the vaneless space to avoid the adverse effect of the transition of the dominant frequency of the rotor–stator interaction on the structural response of the station.