Abstract
Abstract The present paper deals with the side effects of propellers cavitation, i.e. pressure pulses and radiated noise. These effects are gaining more and more importance for commercial ships for different reasons. Pressure pulses significantly affect comfort onboard, thus their reduction is of utmost importance for all ships carrying passengers. As regards the underwater radiated noise, in the last decade interest has shifted from navy applications to commercial ships, due to the concern for the rising background noise in the oceans. The propellers, generating noise directly in water, represent one of the main contributions to the overall underwater noise emitted from ships. Due to the complexity of the mechanisms of propeller noise generation, different complementary strategies have to be followed to properly analyze the problem, ranging from induced pressure pulses to broadband noise and cavitation. In the present work, part of the activities carried out in the framework of the collaborative EU FP7 project AQUO (Achieve QUieter Oceans by shipping noise footprint reduction, www.aquo.eu) are reported. The paper presents the investigations carried out on a specific test case represented by a single screw research vessel, which is analyzed with three different strategies: numerical calculations, model scale investigations and fullscale measurements.
Highlights
The present paper deals with the side effects of propellers cavitation, i.e. pressure pulses and radiated noise
In the framework of the AQUO project, the numerical activities carried out by the University of Genoa have been devoted to the development and validation of computationally affordable tools for the numerical prediction of propeller pressure pulses
For what regards the inflow wakes, both the full-scale nominal and effective wake, numerically evaluated with the coupled Boundary Element Method (BEM)/RANSE approach, have been considered and pressures have been calculated with the model tests configuration and with the full-scale configuration in both cases
Summary
Abstract: The present paper deals with the side effects of propellers cavitation, i.e. pressure pulses and radiated noise These effects are gaining more and more importance for commercial ships for different reasons. Various methods to approach this problem have been proposed during years by different authors, ranging from potential flow solvers (lifting surface and panel codes) to more accurate and time demanding viscous codes (RANSE solvers) The application of these numerical approaches leads, to different levels of accuracy and complexity, which depends on the functioning point considered (e.g. design pitch or reduced pitch for CPP, cavitation extent, etc.). Anthropogenic noise can have different effects on the cetaceans, ranging from hearing permanent or temporal injuries to behavioural changes and communication masking The latter aspect, in particular, seems to be directly correlated to the increase in the last decades of the diffused background noise in the oceans due to the parallel increase of the world-spread shipping traffic.
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