ATENA Conferences System, NAV 2015 18th International Conference on Ships and Shipping Research

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Wall pressure and structural models for self-noise predictions
Elena Ciappi

Last modified: 2015-05-05

Abstract


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 are used in this work  to analyze the case of non-equilibrium 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 on flat surfaces in fully developed and nearly zero pressure gradient flow. The possibility to provide predictive case independent semi-empirical models for the different frequency ranges of wall pressure spectra is also analyzed. Finally, different approximations for the pressure loads are used to numerically evaluate the structural response. The results of this analysis are compared with acceleration experimental data showing that under some conditions and in some identified frequency ranges, the evaluation of the vibro-acustic response can be significantly simplified. 


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