Evolution of Vortex At The Runner Area of Pump-Turbine Under The Runaway Condition

To study the evolution principle of the coherent structure in the low flow rate runaway condition, the pump-turbine of the certain pumped storage power plant is employed. The transient dynamic stress of the runner has been numerically simulated and examined in this study, in order that can probe the mechanism of channel vortices acting on the blade and the evolution of their coherent structure in the runner. Based on the Realizable k-ε turbulent model, the unsteady flow of the whole pump-turbine channels is calculated. Results show that the flow in the runner channels presents with the turbulence state, and with many different scales vortices. These vortices structures are mainly distributed in the inlet region of the blade, the area of the blade trailing edge and the middle section of the runner channels. These vortex structures affect the distribution of the blade pressure load. Moreover, vortices structure at the inlet of the runner depends on the change of the attack angle. In the flow region formed at the outlet of the blade near the suction surface and the runner cone, the blade has a limited effect to the fluid, thus the vortex structure depends on the Coriolis force and the centrifugal force joint action.