Author(s): M Zorn; K Khalfaoui; O Kirschner; S Riedelbauch

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Abstract: As pump-turbines are increasingly operated in offdesign conditions, the flow behaviour and resulting pressure fluctuations at different deep part load conditions of a pump-turbine are investigated using CFD simulations. The general flow behaviour at deep part load is determined by the flow misalignment at the leading edge and the non-optimal outflow at the trailing edge of the impeller. The flow misalignment at the leading edge leads to vortex formation and resulting pressure fluctuations. The non-optimal outflow at the trailing edge causes a backflow in the draft tube, which extends into the impeller and also generates vortices there. This backflow can reach up to the leading edge, further deteriorating the misalignment of the flow at the leading edge. Both phenomena become more pronounced as the discharge and head decrease.

DOI: https://doi.org/10.1088/1755-1315/1561/1/012029

Year: 2025