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Experimental study of the structure and dynamics of cavitating flows

Abstract : Cavitation is a complex phenomenon involving mass transfer between liquid and vapour phase at nearly constanttemperature. Advances in the understanding of the physical processes of cavitating flows are challenging, mainlydue to the lack of quantitative experimental data on the two-phase structures and dynamics inside the opaquecavitation areas. In this thesis, partial cavitation developed in small convergent-divergent (Venturi) channels wasstudied experimentally in detail for a better knowledge of the physical mechanisms governing the cavitationinstabilities. This was achieved by using an ultra-fast synchrotron X-ray imaging technique aided withconventional high speed photography and Particle Image Velocimetry. The main contributions of the presentstudy can be summarized as follows: (1) detailed description of the two-phase flow structures in quasi-stablesheet cavitation, which is characterized by a low-speed re-entrant flow existing continuously underneath thecavity; (2) analysis of the complex effect of cavitation on turbulent velocity fluctuations; (3) identification ofthree distinct mechanisms responsible for the transition of sheet-to-cloud cavitation, with a discussion of thedifferences between them; (4) analysis of the scale effect on cavitation in the studied Venturi flows.
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Submitted on : Wednesday, February 3, 2021 - 12:00:22 PM
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  • HAL Id : tel-03130085, version 1

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Guangjian Zhang. Experimental study of the structure and dynamics of cavitating flows. Electric power. HESAM Université, 2020. English. ⟨NNT : 2020HESAE050⟩. ⟨tel-03130085⟩

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