Counter-rotating type pump-turbine unit cooperating with wind power unit

This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind. In this paper, the tandem impellers of the counter-rotating type pumping unit was operated at the turbine mode, and the performances and the flow conditions were investigated numerically and experimentally. The 3-D turbulent flows in the runners were simulated at the steady state condition by using the commercial CFD code of ANSYS-CFX ver.12 with the SST turbulence model. While providing the pump unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runner/impeller of the unit works evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet without the guide vanes. These results show that this type of unit is effective to work at not only the pumping but also the turbine modes.