Extensive Cavitation Tunnel Acoustic Characterization of Controllable Pitch Propellers

Experimental tests in model-scale are the currently established (and more reliable) methods for the propeller acoustic characterization. However, they are affected by uncertainties mostly due to scale effects, which make it difficult to consistently reproduce in model-scale some of full-scale functioning conditions. In order to cope with this issue, it is interesting to define empirical formulations to shape the most significant cavitating phenomena in terms of URN spectrum. A suitable approach for the determination of such formulations may consist in the experimental characterization of model propellers collecting a large amount of data such to accurately describe propeller functioning conditions and related noise emissions. Collected data should be then analysed to extrapolate desired formulations exploiting advanced data analysis techniques. In the present work the acoustical characterization of two propellers, performed at the University of Genoa cavitation tunnel, is presented. The collected sample includes cavitation buckets with inception points of different phenomena, noise spectra, pressure pulses and photos picked up at various pitches and functioning points, including off design conditions.