Large Eddy Simulation of Cavitating Flow on Hydrofoils

Licentiatavhandling, 2010

Cavitation is the occurrence of vapour pockets in liquids due to the phenomenon that liquid may turn into vapour when the pressure in the flow is lowered below the vaporization pressure. It often brings negative effects such as performance degradation, noise and vibration, and material damage, therefore becoming one of the limiting factors when designing the propulsion systems. Experiments can offer direct visualization of this complex process however analysis is quite limited. Together with accurate numerical predictions, a more complete picture of the cavitation process may appear, allowing detailed investigations to help improving both the understanding of the mechanisms as well as the design. In this thesis, numerical simulations of cavitating flow on hydrofoils are carried out using Large Eddy Simulation in combination with homogeneous mixture assumption based on a volume of fluid implementation to capture the liquid-vapour interface and Transport Equation-based Methods for the mass transfer between the phases. The overall results are encouraging, with a globally satisfactory agreement with the experiments in terms of the main cavitation and flow mechanisms, indicating the current methodology has a great potential to become a useful and reliable tool in contributing to preventing or reducing cavitation effects and improving the general performance of the propulsion system. Keywords: Cavitation, modeling, hydrodynamics, numerical simulation, LES