Reduction of flow energy dissipation (FED) in pump-turbine is important in improving the energy conversion efficiency of pumped storage power station. By eliminating obvious undesirable flow regimes, the efficiency of modern pump-turbines is higher than 90% in both pump and turbine modes. However, the further efficiency improvement is difficult because it is hard to visualizing, locating and quantifying FED. Based on Computational Fluid Dynamics (CFD) and thermodynamics evaluation, the irreversible FED features in a reversible pump-turbine is comparatively analyzed in pump mode and turbine mode. By analyzing different off-wall distance zones, the near-wall ( 10 mm) regions are found with high FED. By comparing different components, runner is found as the main FED source (proportion >50%). The stators downstream to runner (vanes in pump mode and draft tube in turbine mode) has also high FED due to local vortical flow. FED in pump-turbine is found with different sub-types. The viscosity-dominated type is found with local increasing of turbulence kinetic energy and temperature. The striking-dominated type is found with local sudden velocity reduction. Targeted elimination of vortical flow, reduction of surface-roughness and improvement of geometry-flow adaptability will be effective in the future high-efficiency design of reversible pump-turbines.

Comparative numerical studies for the flow energy dissipation features in a pump-turbine in pump mode and turbine mode

Evolution mechanism of a prototype pump turbine after pump power-off

Optimization of blade high-pressure edge to reduce pressure fluctuations in pump-turbine hump region

Pumped storage hydro (PSH) is a mature and widely used energy storage technique. The hydraulic dissipation of PSH will lead to the decline of power station efficiency. Therefore, it is important to find the reasons flow energy dissipation (FED). The adjustment of the flow channel will cause the change of flow energy dissipation. Guide vane is an important component of pump turbine, which has an influence on the problems of FED. In this paper, the FED in pump turbine with two guide vane profiles are analyzed. The combination of experimental method and numerical simulation method is adopted. Through experiments, the influence of two guide vane profiles on performance is clarified, and the method to judge the severity of Q-H instability is proposed. The FED under different working conditions were analyzed by entropy production. When the flow rate is at design point, the wake and local small flow separation causes FED. When the flow rate is large, FED is caused by the strong wake and flow separation in the runner. When the flow is small, the complex flow pattern in guide vane and back-flow cause high FED. The guide vane profiles have a great influence on FED. The match of blade leading edge and flow direction and flow control ability of guide vane affect the flow state caused the variation of FED. 

Influence of guide vane profile on the flow energy dissipation in a reversible pump-turbine at pump mode

Owing to the complexity of the load rejection process, the accompanied complex low frequency pressure fluctuations and their sources have not been determined. Herein, the load rejection transient p...

Hong Chang

Papers

Mechanism of low frequency high amplitude pressure fluctuation in a pump-turbine during the load rejection process

Aerodynamic characteristics and mechanisms for bionic airfoils with different spacings

Experimental investigation of hysteresis on pump performance characteristics of a model pump-turbine with different guide vane openings

Bionic leading-edge protuberances and hydrofoil cavitation

Effects of Reynolds Number and Protuberance Amplitude on Twin-Protuberance Airfoil Performance