Feasibility study of the application of fibre-optic hydrophone as monitoring sensor to detect the cavitation inception

The detection of the cavitating behaviour of a marine propeller can provide very useful information at sea, especially for navy ships that for survivability reason must be as silent as possible. So, a monitoring system able to accurately check the inception of cavitating phenomena can provide the crew very important support to handle the ship in the best way consistently with the mission currently underway. For this reason, a special application of fibre-optic sensor was investigated during the three years long research project “Digital Ship Structural Health Monitoring” (dTHOR) founded by the European Defence Fund (EDF) under the grant agreement 101103257 dTHOR—EDF-2021-NAVAL-R-2. Under the coordination of the team aimed to work on the hydro-acoustic signature control, CETENA carried out a deep feasibility study to understand if a fibre-optic hydrophone can be adopted to monitor in real time the hydrodynamic behaviour of a propeller and hence to provide reliable indication to the crew about what is really happening during the ship life. This paper describes the study done, covering all the aspects of the adoption of the proposed solution that are: definition of the position for the sensor arrangement, the assessment of its performance, effects on the propeller behaviour and design of its mechanical support. • The detection of the cavitating behaviour of a marine propeller in real-time through fiber-optic hydrophone application. • Monitoring system able to check the cavitation inception, providing important support to handle the ship acoustic signature. • Design of mechanical sensor support and its effect on propeller hydrodynamics. • Numerical predictions through low- and high- fidelity methods to evaluate propeller pressure field and its effect on noise.