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Energy loss mechanism of pump-turbines in the hump region using novel wall entropy production calculation model

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  • Fu, Xiaolong
  • Chen, Yong
  • Li, Deyou
  • Wang, Hongjie
  • Li, Zhenggui
  • Wei, Xianzhu

Abstract

The traditional entropy production (EP) theory faces challenges such as ambiguous mechanisms governing energy dissipation in the hump region of pump-turbines and imprecise quantification of hydraulic losses within near-wall regions. Therefore, this study proposes a novel wall entropy production calculation model (WEPM) that combines the boundary layer theory and the finite volume method. Additionally, this study utilizes a 3D flow simulation method for a high-head prototype pump-turbine. The reliability of WEPM was verified by comparing it with the pressure difference method. The results show that the impeller clearance and stay/guide vanes are the main sources of energy loss in the hump region (the stay/guide vanes collectively contribute up to 44 % of the total hydraulic losses). WEPM precisely quantified the EP between the core flow and near-wall regions. Visualization of the flow field revealed that the separation vortex at the impeller outlet, guide vane trailing edge, and clearance jet vortex were the core mechanisms of high entropy production rate under low part-load conditions. The relationship between the pressure pulsations and vortices generated by non-uniform velocity gradients was also identified. This study provides a valuable method for quantitative analysis of near-wall EP in hydraulic machinery.

Suggested Citation

  • Fu, Xiaolong & Chen, Yong & Li, Deyou & Wang, Hongjie & Li, Zhenggui & Wei, Xianzhu, 2026. "Energy loss mechanism of pump-turbines in the hump region using novel wall entropy production calculation model," Renewable Energy, Elsevier, vol. 258(C).
    • Handle: RePEc:eee:renene:v:258:y:2026:i:c:s0960148125026266
    DOI: 10.1016/j.renene.2025.124962
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    References listed on IDEAS

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