Ciappi E., Magionesi F.

In view to evaluate the noise radiated by elastic ship’s element excited by the turbulent boundary layer (TBL), an experimental and theorethical procedure has been developed to characterise the hydrodynamic pressure load and the vibro-acoustic response of an hull plate. Although during the last thirty years a lot of work has been made on this subject and several models devoted to the representation of the pressure load exist, most of the obtained results are valid only for particular tested conditions. In this work, using the results of different experimental campaigns performed in a towing tank on different ship’s models, a complete procedure based on experimental test at model scale for the characterisation of the hydrodynamic load and for the evaluation of the vibrational response and on numerical simulations for the prediction of the radiated noise is described. All the steps have been validated, at model scale, by comparison with available experimental data and with the results of numerical simulations. Since the the hydrodynamic load is here modeled on the basis of universal scaling laws, this procedure can be applied to real case once few information on the full-scale TBL velocity parameters are available. Thus, the noise level generated on board a real ship has been evaluated and a parametric study, varying the hydrodynamic and the structural parameters, has been performed to investigate the mechanism of noise radiation.