Prediction of underwater radiated noise from propeller cavitation during concept design

There is growing concern about the impact of underwater radiated noise (URN) on marine life. One of the main sources of URN of ships is propeller cavitation. Semiempirical computational models to predict back (suction) side cavitation at the design point of open propellers have been published, but there is a lack of models that predict the URN of open propellers in off-design conditions and the URN of ducted propellers, such as thrusters.

The European Union NAVAIS 1 project considered two ship types that spend large proportions of time operating at offdesign conditions – a road ferry and an aquaculture workboat – and are therefore likely to experience several
different forms of propeller cavitation. The present paper discusses new semi-empirical models to be used together
with a boundary element method for predicting noise from these forms of cavitation. The new (medium-fidelity) models were tuned using data from a large series of modelscale noise measurements, supplemented by high-fidelity
scale-resolving computational fluid dynamics simulations combined with the Ffowcs Williams-Hawkings acoustic analogy. The medium-fidelity models were used to predict the URN from a large series of propellers for a wide range of operating conditions, with the results used in a regression analysis to develop a low-fidelity tool for estimating propeller URN of road ferries and workboats during the concept design phase.