WALL PRESSURE MODELS FOR SELF NOISE PREDICTION

In the last years, several research projects have been devoted to the understanding of the characteristics of the self-noise induced by turbulent flow around the hull of military surface and underwater vessels. Experimental setups and test campaigns have been designed to measure, in the CNR-INSEAN towing tanks, wall pressure fluctuations on surfaces of different geometries and the induced vibro-acoustic response, varying flow conditions and structural material properties. In particular, experimental data concerning a bulbous bow of a military vessel and a catamaran model are used in this work to analyze the case of non-stationary and inhomogeneous boundary layers. These flow conditions typically occur when free surface effects, as well as surface curvature and transitional phenomena cannot be neglected. The results are compared with some literature data and with other measurements acquired in the towing tank in nearly canonical flow conditions. The possibility to provide predictive case independent semi-empirical models for the different frequency ranges of interest is analyzed. Finally, different approximations for the spatial variation of the pressure load are proposed and validated through the comparison between the numerical and experimental structural response.