Acoustic characterization of a cavitation tunnel for ship propeller noise studies

The noise radiated by ship propellers can be studied by analyzing scaled models in a cavitation tunnel. However, transferring the measurements made in the enclosed space of the tunnel to the expected values in a full-scale propeller (in a free field) presents a challenge for noise measurements. An acoustic characterization of the DITEN cavitation tunnel, including a study of normal modes and acoustic response to harmonic sources, is presented to understand the primary acoustic behaviour of the enclosure and its propagation characteristics. A three-dimensional numerical model was developed to simulate the DITEN Genoa University cavitation tunnel and evaluate the influence of elements such as a dynamometer, fins, impeller, and source position on the acoustic response of the tunnel. The study showed the influence of the mentioned elements on the acoustic response of the tunnel, and the numerical predictions were validated by comparing them with the experimental campaign in the low-mid frequency range. The study provides valuable insights into the behaviour of sound waves in a cavitation tunnel and the influence of various factors, which can help design and optimize cavitation tunnels and related experiments.