ACOUSTIC CHARACTERIZATION OF A CAVITATION TUNNEL: MODAL BEHAVIOUR AT LOW FREQUENCIES

Scaled models are implemented to study the radiated noise from the ships' propellers. Typically, acoustic measurements are performed inside a cavitation tunnel using those scaled models of the propeller. This work aims to present a modal acoustic characterization of the cavitation tunnel of the DITEN department of the University of Genoa in the low-frequency zone (i.e., below 1 kHz). A three-dimensional numerical model was used to simulate the tunnel, helping to understand the enclosure's modal behavior. Normal modes were classified using the modes for a toroidal-like enclosure. As expected, the modal density increases for each third-octave band, making it possible to determine the frequency limit where the behavior of the tunnel changes from modal to diffuse.