Cavitation implosion loads from energy balance considerations in numerical flow simulations

Abstract

Cavitation erosion is a problem in the design of a wide range of fluid machinery involving liquid flows. Ship propellers, rudders, hydro pumps and turbines or diesel injectors are some of the most prominent examples. Cavitation occurs at locations of high local flow velocity, where the pressure may drop so low that the liquid phase vaporizes. The violent collapse of cavitating structures in regions of pressure recovery can result in high pressure loads and severe damage of such devices. Erosive cavitation is typically encountered when the hydrodynamic efficiency of fluid machinery is optimized. In order to find an appropriate balance in the design trade-off between hydrodynamic efficiency and the risk of cavitation erosion damage, there is a need for computational tools that can predict the risk of cavitation erosion in the early design and optimization process. The prediction of cavitation erosion risk using Computational Fluid Dynamics (CFD), however, is a major challenge because the local erosion damage is the result of extreme pressure loads forming at the final stage of cavity collapses at extremely small scales in both space and time. Due to limited computational resources, such small scales can usually not be resolved for flow problems relevant to engineering applications...