Numerical Models for the Prediction of Ship Airborne Noise Emissions

The airborne noise emitted by ships represents a pollution source affecting the surrounding environment and third parties. Nowadays, in addition to numerous other kinds of environmental impacts due to shipping activities, ship airborne radiated noise in the latest years has captured the attention of universities, industries, and Regulatory Bodies. Even though this problem can be quite annoying and has raised serious complaints from the citizens of areas close to ports, shipping routes along the coast, or inland waters, the acoustic impact of ships to date has not been subjected to systematic control. The problem is primarily driven by the presence of powerful sound sources on ships and the fact that inhabited areas are often in close proximity to areas where ships operate. In response to the need to regulate the noise emitted by ships, Lloyd's Register introduced a class notation in 2019 specifically for airborne noise emissions from ships. This notation also includes a procedure for granting the notation. Within this context, the development of mathematical models to predict the propagation of noise in the air can serve as a valuable tool for anticipating and controlling the impact of ship-related airborne noise. This paper, reports problems and methods on the practical implementation of the required classification checks, in particular as regards the simulation and validation problems. As an application example, a small part of the results obtained during an industrial research activity aimed at assessing the noise radiated into the air by a passenger ship is reported.