Experimental measurements and numerical simulations of underwater radiated noise from a model-scale propeller in uniform inflow

Propeller-induced cavitation dominates the underwater radiated noise emitted by ships, presenting a significant threat to marine ecosystems. Designing mitigation strategies for noise pollution requires predictive models, which are challenging to develop due to the varied, multiscale, and multi-physical nature of the phenomenon. One technique for predicting the propeller cavitation noise source that is rising in popularity relies on the use of computation fluid dynamics (CFD) solutions of the cavitating flow with a volume-of-fluid cavitation model. We measured cavitation induced noise from ten loading conditions of a model-scale controllable pitch propeller in uniform inflow, resulting in four distinct regimes of cavitation. These experimental conditions were reproduced numerically using the unsteady Reynolds-averaged Navier-Stokes (URANS) framework, facilitating direct comparison between the experimental and the numerical results. Vapour cavities attached to propeller blades were adequately simulated, while regimes involving cavities within shed vortices were not reproduced well. The numerical model effectively predicted the qualitative trends of acoustic spectra, but the absolute sound levels were over-predicted. These results provide insight into the necessary components of a successful propeller noise model and outline the advantages and shortcomings of the present numerical framework.