PROPELLER TONAL NOISE SCATTERED BY MARINE VEHICLES IN CRUISE MOTION

Tonal noise generated by screw-propellers in behind-hull condition is analyzed by a non conventional form of the Ffowcs-Williams and Hawkings Equation (FWHE). It is applied to predict the distribution of the acoustic pressure field upon moving bodies impinged by periodic pressure pulses emitted by the propulsor accounting for hull acoustic scattering effects. By combining an unsteady three-dimensional (3D) panel method and the Bernoulli equation, the sources of sound over propeller blades and the incident pressure field on the scatterer are detected. Two types of scatterer bodies are considered: a small-thickness plate, resembling the rear portion of a vessel hull-plate, and the bare-hull of a model submarine. For both configurations, numerical results are compared with computations from a hydrodynamic panel method where propeller and hull are solved jointly.