Effect mechanism of cavitation on the hump characteristic of a pump-turbine
TL;DR: In this paper, the effect of cavitation on the hump characteristic of pump-turbines was investigated using the SST (shear stress transport) k-ω turbulence model and ZGB (Zwart-Gerber-Belamri) model.
About: This article is published in Renewable Energy.The article was published on 2021-04-01. It has received 44 citations till now. The article focuses on the topics: Cavitation.
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TL;DR: In this article, the irreversible flow energy dissipation (FED) features in a reversible pump-turbine were analyzed in both pump and turbine modes and different sub-types of FED were found.
Abstract: 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.
27 citations
TL;DR: In this article, two optimization strategies for high-pressure edge shape of runner blades have been proposed to reduce the high-amplitude pressure fluctuation in the hump region, and a large eddy simulation was performed to study the optimization effect.
18 citations
TL;DR: In this article , two optimization strategies for high-pressure edge shape of runner blades have been proposed to reduce the high-amplitude pressure fluctuation in the hump region, and a large eddy simulation was performed to study the optimization effect.
17 citations
01 May 2022
TL;DR: In this paper , the influence of two guide vane profiles on performance is clarified, and the method to judge the severity of Q-H instability is proposed. And the combination of experimental method and numerical simulation method is adopted.
Abstract: 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.
17 citations
TL;DR: In this paper , the authors used the transient numerical simulation method to study the evolution characteristics and pressure pulsation of the vortex in the dustpan-shaped conduit when the axial-flow pump as turbine (PAT) runs.
16 citations
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TL;DR: In this paper, the authors have carried out numerical simulations of a tip leakage cavitating flow, generated by a straight NACA0009 hydrofoil, using Lagrangian coherent structures (LCSs) combined with Schnerr-Sauer cavitation model.
205 citations
192 citations
TL;DR: In this paper, a 3-dimensional (three dimensional), compressible, cavitating flows in a pump-turbine at pump mode were numerically studied using SST k-ω turbulence model and mixture model.
85 citations