Near field propeller radiated noise measurements: model and full scale experimental data comparison

Abstract

The ever rising interest related to the underwater no1se originating from cavitating propellers prompted the Italian Navy to study this aspect of naval architecture in an experimental way. This was accomplished carrying out extensive model tests in the Italian Navy cavitation tunnel (CEIMM) and full-scale tests in cooperation with CETENA. This paper outlines the measuring technique theacoustic behaviour of the cavitation tunnel as well as the measuring technique and analysis of full scale tests carried out with hull-mounted hydrophones. Some problems arising from both these kinds of measurements and their analySlS methodology are highlighted. A technique to take account hull boundary and hull vibrations, during full-scale tests, is also discussed. Finally some results of "near field" propeller noise, obtained from both model and full-scale measurements, are shown and compared.