CAVITATION DYNAMICS AND UNDERWATER RADIATED NOISE SIGNATURE OF A SHIP WITH A CAVITATING PROPELLER

The paper presents SSPA's work in the EU project AQUO to predict underwater radiated noise (URN) generated by a coastal tanker with a cavitating propeller. A CFD method, consisting of a multi-phase Delayed Detached Eddy Simulation (DDES) and a Ffowcs Williams-Hawkings (FWH) acoustic analogy, is applied to predict the cavitation, pressure pulses and radiated noise for the ship at model and full scale. In comparison with the data obtained from the model test and full scale measurement, it is found that the predicted sheet cavity correlates quite well with the observed ones in the experiment and sea trial. Some success is made in predicting the collapse and rebound of tip vortex cavitation (TVC) at model scale, yet the extension of TVC is under-predicted. The predicted pressure pulses agree reasonably well with the measured ones at the first three harmonics, deviation becomes larger at higher harmonics. The tonal noise has fairly good agreement with the measured signal at both scales up to 5th harmonics. The simulation however under-predicts part of broadband noise that is caused by the TVC, mainly due to an under-resolution of the flow in the tip region and the propeller wake. The agreement with the data for the model scale case is slightly better than that for the full scale case.