Prediction of Marine Propeller Noise:Theoretical Models Compared. Part II - Cavitating Flow

The aim of this report is to describe two theoretical models aimed to cavitation noise prediction. Both models are based on the Ffocws Williams and Hawkings equation and have been used to analyse, numerically, the noise signature due to the unsteady behaviour of the cavitaion bubble occurring on marine propeller blades during typical operating condition in the wake of the hull. Although the application of these models have yieled promising results in terms of noise, considerable efforts have to be devoted torward understanting some phyical correlation between the dynamics of the vapor bubbles and the radiated noise. It is notable that a correct estimation of the induced- pressure distribution on the hull-plate may be achieved only if, apart from scattering effects, a physically consitent evaluation of the noise related to cavitation dynamics is accounted for; hence, for any activity involving cavitation noise, it is important to use assessed and efficient hydroacoustic tools. For these reasons, this report emphasizes the physical assumptions at the basis of the hydroacoustics tools that will be used to achieve a comprenhensive evaluation of the noise radiated by a whole configuration hull-propeller.