Prediction of cavitating propeller underwater radiated noise using RANS & DES-based hybrid method

This study focuses on the prediction of the hydrodynamic and hydroacoustic performance of a cavitating marine propeller in open water condition using Reynolds-averaged Navier-Stokes (RANS) and Detached Eddy Simulation (DES) solvers. The effectiveness of the methods is investigated for the recently introduced benchmark propeller that belongs to the research vessel 'The Princess Royal'. The main emphasis of the study is to examine the capabilities of the RANS and DES solvers for predicting the hydrodynamic performance of a propeller in the presence of sheet and tip vortex cavitation (TVC). In the numerical simulations of the cavitating propeller flow, the Schnerr-Sauer cavitation model based on a reduced Rayleigh-Plesset equation was used to model the sheet and tip vortex cavitation. An alternative Vorticity-based Adaptive Mesh Refinement (V-AMR) technique was employed for the accurate realisation of the TVC in the propeller's slipstream. In the hydroacoustic calculations, a porous Ffowcs Williams Hawkings equation (P-FWH) was employed together with the DES solver. The numerical hydrodynamic and hydroacoustic results are compared with those of experimental data for the benchmark propeller available from the University of Genova Cavitation Tunnel. The results show that both the RANS and DES solvers are successful for modelling of the sheet cavitation on the propeller blades. However, the prediction of the TVC extension using the RANS solver is found to be insufficient in comparison to the TVC prediction when using the DES method. This is due to the inherent modelling limitations of the RANS solver. In addition to hydrodynamic performance predictions, the overall noise spectrums were found in an agreement with the experimental data with discrepancies between the low and high-frequency region.