Study on the Influence of Gap Water Body on the Modal Characteristics of Pump Turbine Runner.

The pump turbine runner is a key structural component of the unit, and its modal characteristics directly affect the safe and stable operation of the unit. Taking into account the real operating environment of the runner, this paper uses numerical simulation to study the effect of gap water body on the natural frequency and mode shape of the runner. The results show that the combination of the gap water body and the flat rotor structure of the runner has a significant influence on the modal characteristics of the runner. For the natural frequency of the runner, the gap water body will greatly increase the added mass coefficient, and the natural frequency will drop sharply. Without the restriction of the gap water body, the modal displacement of the runner will have more fluctuations. Moreover, the shape, amplitude and maximum modal displacement point of the modal displacement curve have all changed.