Comparison on the Pump Turbine Hydraulic Performance and Internal flow in S-Curve Region by Specific Speed

The demand for pump turbines is increasing to eradicate the fluctuating, unpredictable, and delocalized energy production from wind and solar. The pump turbine design and the geometrical shape (diameter and width ratios) are based on specific speeds. The pump turbine's specific speed directly influenced hydraulic performance and internal flow behavior. Besides hydraulic performance and internal flow, the pump turbine encounters the S-Curve region when operating at a partial flow rate in turbine mode. The S-Curve region is sensitive to the geometrical shape of the pump turbine. At S-Curve region and partial flow conditions, the high specific speed pump turbine has better flow characteristics than a low specific speed pump turbine.