Abstract

Flow in fluid machinery can include multiphase phenomena such as cavitation due to energy exchange between the machinery and flow of a liquid, which, in turn, produces local drops in pressure and, therefore, evaporation. When vapor structures are subjected to increased pressure, they collapse during the process of condensation. These collapses are driven by high ambient pressure and can, over time, induce damage to the fluid machinery solid walls—a process termed cavitation erosion. In addition, fluid machinery such as water turbines and pumps often operate in water that is not pure. In this water, solid particles can be present, for example, river sediment, which can also produce erosion. In the past, these causes of erosion were mostly investigated separately; however, as they sometimes occur simultaneously, studies that replicate these conditions are necessary. In the present work, we investigated the erosion of a Venturi channel surface with several different divergent angles using CFD simulations, which were validated experimentally using the soft paint method. Results showing the cavitation and particle erosion were obtained for different flow conditions (specifically with different vortical structures) that are expected to occur in fluid machinery. The results suggest that cavitation modifies the flow field in a manner that affects particle-induced erosion, leading to different macroscopic erosion patterns.

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