Cavitation Erosion Prediction at Vibrating Walls by Coupling Computational Fluid Dynamics and Multi-body-Dynamic Solutions

Cavitation erosion caused by high-frequency vibrating walls can appear in the cooling circuit of internal combustion engines along the liners. The vibrations caused by the mechanical forces acting on the crank drive can lead to temporary regions of low pressure in the coolant with local vapor formation, and vapor collapse close to the liner walls leads to erosion damage, which can strongly reduce the lifetime of the entire engine. The experimental investigation of this phenomenon is so time consuming and expensive, which it is usually not feasible during the design phase. Therefore, numerical tools for erosion damage prediction should be preferred. This study presents a numerical workflow for the prediction of cavitation erosion damages by coupling a three-dimensional (3D) Multi-Body-Dynamic (MBD) simulation tool with a 3D Computational Fluid Dynamics (CFD) solver. The multi-body simulation provides the space and time-resolved wall displacements that act as oscillatory boundary conditions for the multiphase flow simulation calculating the vapor formation and the erosion prediction along the liner walls. The CFD model is validated with an acoustic horn test case from the literature. The sub-frequency of vapor formation matches the one measured during experiments. Next, this model setup is applied in a real-case six-cylinder combustion engine. The erosion damage probability of two engine temperature conditions, a warm and a cold engine cooling circuit, is investigated, showing more erosion damage for the latter one. The presented simulation workflow determines a helpful tool during the engine development process since it allows the comparison of different engine designs and operation points with respect to the probability of incurring cavitation erosion damages.