Contribución a la cuantificación del ruido radiado por los buques a través de su casco

Résumé

In this doctoral thesis, three main contributions are made to quantify the radiated noise by ships through their hulls. Firstly, the analysis of a monitoring campaign of the noise radiated by ships in a port environment is presented. This study shows the increase in underwater noise pollution generated by maritime traffic and the need to establish methodologies for the control of noise radiated by ships with the aim of mitigating it. In addition, the study reveals the improvable choice of acoustic parameters promulgated by the European Union to define good environmental status. The noise generated by a ship is made up of the contribution of various sources. The second and third contributions are directly related to the problem of ship hull radiation generated by vibrations induced by machinery and other vibrating elements installed on board. Due to the structural complexity of a ship, as a prior step to the study of its radiation, an analysis of the vibroacoustic behaviour of simple circular structures in the laboratory has been carried out, radiating both in air and in water with the aim of allowing extrapolation of applied conclusions when the environment is air to a water propagation medium. This analysis makes possible to verify that the radiation from a sound source not only depends on the material and boundary condition of the structures, but also on the type of medium to which it radiates. The analysis of the radiation from the hull of ships has been carried out applying analytical methods to the calculation of radiation efficiency and experimental verification in a real ship. To do this, measurements of the acceleration of the hull and sound pressure are performed simultaneously, obtaining a data set that allows determining the optimal location of the accelerometers, evaluation of the estimations of the transfer function and the validation and applicability of analytical methods for the estimation of radiation efficiency