Numerical Prediction of Cavitation Erosion Induced by Cavitating Jet Using Eulerian–Lagrangian Modeling

Abstract

The cavitation-induced erosion is widely found in fluid machineries and always leads to material loss. Apart from its destructive nature, it is also useful in many fields such as the cleaning or slicing. In the present work, a numerical framework accompanied with a multiscale cavitation model is developed for addressing cavitation erosion risks. The energy transfer between the collapsing vapor and the eroded surface is assessed by an aggressiveness indicator considering the changes in both local instantaneous pressure and vapor volume fraction. Two improvements are made compared with previous works. Firstly, a Eulerian–Lagrangian method is introduced to simulate the multiscale cavitation, in which the volume of fluid (VOF) method and a discrete bubble model (DBM) are combined for reproducing the resolvable water-vapor interface and unresolvable micro bubbles, respectively. Secondly, the qualitative and quantitative effects of microscale bubble on cavitation erosion are discussed. For validation, the proposed numerical modeling framework is applied to predict the erosion of aluminum surface caused by a cavitating jet, and it is shown that the simulated erosion region fits well with the experimental observation. The present simulation reveals that the sensitivity of cavitation erosion indicator to the pressure change outweighs that to the change vapor volume fraction. And the microscale bubbles play a critical role in shaping the distribution of cavitation erosion.

Keywords: cavitating jet, erosion, Numerical simulation, multiscale model, volume of fluid, microscale bubble