Inclined-Flow Propeller Hydroacoustics by the Permeable Ffowcs Williams Hawkings Equation

In this paper the noise hydrodynamically generated by noncavitating marine propellers in non- axial flow condition is investigated. The permeable Ffowcs Williams and Hawkings Equation (FWH-P), solved by a Boundary Element Method (BEM), is used to radiate sound outward a suitable fictitious surface that encloses all the sources of sound related to the propeller and flow- field around it. To this aim, the fluctuating velocity and pressure field distributions required upon the permeable surface are obtained by a Detached Eddy Simulation (DES). For validation pur- poses, the acoustic signatures evaluated by the combined DES/FWH-P approach are compared with those directly computed by the hydrodynamic solver for observers placed in the near field. Keywords: Propeller hydroacoustics, Oblique flow, Acoustic Analogy, Permeable surface tech- nique.