Experimental analysis of the influence of ship wake scaling on marine propeller radiated noise and pressure pulses

The propeller performances and in particular the non-stationary cavitating behavior and its side effects, i.e. pressure pulses and radiated noise, are strongly dependent on the ship wake field. Many different predictive methods are available, however in many cases predictions are still performed on the basis of semi-empirical approaches, whose validity is doubtful. In parallel to this, the ever increasing power of computational tools (namely RANS solvers) allows for a direct numerical prediction of the ship full scale wake. In the present paper, the effect of the adoption of two different full scale wakes obtained with semi-empirical methods and direct computations is evaluated experimentally by means of cavitation turmel tests on a model propeller, focusing the attention not only on mechanical characteristics and cavitation extents but, specifically, on pressure pulses and radiated noise. The results of this study put into evidence the differences which may be expected using the two different scaling approaches.