Verification and validation of large eddy simulations of turbulent cavitating flow around two marine propellers with emphasis on the skew angle effects

Abstract

Large eddy simulation (LES) was used to simulate turbulent cavitating flow around a conventional marine propeller (CP) and a highly skewed marine propeller (HSP) with emphasis on the skew angles effects. The LES verification and validation (V&V) analysis was carried out with cavitation influence on the flow structures. The current numerical results demonstrate that LES can give excellent predictions of the transient complex cavitating flows around a CP and a HSP with the numerical results agreeing well with experimental data. This study applies the LES V&V to the cavitating flow around two propellers with a simplified three-equation method. The results show that the LES errors for HSP are smaller than for CP, which is mainly resulted by more skewed blade of HSP than CP. In addition, the cavitation-vortex interactions around the propellers were studied using the relative vorticity transport equation. The results indicate that both the baroclinic torque term and the Coriolis force term have important influences on the vorticity generation and transport in the cavity closure region. Further analyses indicate that most of the important flow structures including the tip vortex, leading edge vortex, trailing vortex and internal jet are reproduced by the current LES simulations. Due to the different geometry features (less skewed blade of CP than HSP), significantly more intense and violent vortical structures and cavitation phenomena are observed on the CP than on the HSP.