Author(s): G G Gherghe; T Ciocan; R F Susan-Resiga

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Keywords: No Keywords

Abstract: We develop a novel methodology for investigating numerically the complex hydrodynamics near the tip of Kaplan runner blades, aiming at developing techniques for mitigating cavitation development at full load operation regime. First, a two-dimensional swirling ϐlow analysis in the meridian half plane of the ϐlow passage is used to deϐine a streamtube bounded on one side by the guide vanes lower ring and the runner chamber and on the other side by an axisymmetric streamsurface. Second, this restricted three-dimensional computational domain allows us to focus on ϐlow details corresponding to guide vanes overhanging at full opening, variable tip gap of the runner blades, as well as on the strong interactions between guide vanes wakes and runner blades. We present an in-depth analysis of the ϐlow ϐield and conclude that re-shaping the lower ring of the guide vanes and the runner chamber wall within the framework of Minimum Gap Runner (MGR) technology should be considered for large Kaplan turbines.

DOI: https://doi.org/10.1088/1755-1315/1561/1/012007

Year: 2025