Ship underwater noise assessment by the Acoustic Analogy part II: hydroacoustic analysis of a ship scaled model

In this paper the Acoustic Analogy is used to predict the underwater noise from a complete scaled ship model in a steady course. The numerical investigation is performed by coupling an incompressible RANS code, equipped with a level-set approach to account for the fundamental time evolution of the free surface, to a FWH-based hydroacoustic solver, here suitably designed to manage the huge set of data coming from a full-unsteady hydrodynamic simulation. The results reveal the overall limited contribution from the propeller thickness and loading noise components and the fundamental one from the nonlinear quadrupole sources. The comparison between the hydrodynamic and hydroacoustic solutions point out the noticeable scattering effects due to the hull surface, the possible influence of sound refractions at the free surface and, above all, the leading role played by the turbulent fluctuating component of the velocity field. Finally, by computing the pressure time histories at a prescribed set of virtual hydrophones and turning them into the frequency domain, the ship noise footprint in dB is traced out, thus showing how the Acoustic Analogy can be effectively used to analyze the ship hydroacoustic behavior, both in terms of amplitude and directivity.

[1]  Mario Felli,et al.  Propeller wake analysis in nonuniform inflow by LDV phase sampling techniques , 2005 .

[2]  J. Hildebrand,et al.  Increases in deep ocean ambient noise in the Northeast Pacific west of San Nicolas Island, California. , 2006, The Journal of the Acoustical Society of America.

[3]  Alexander Ya. Supin,et al.  Marine Mammal Sensory Systems , 1992, Springer US.

[4]  Jinhee Jeong,et al.  On the identification of a vortex , 1995, Journal of Fluid Mechanics.

[5]  Christopher W. Clark,et al.  Acoustic Behavior of Mysticete Whales , 1990 .

[6]  Philip R. Staal,et al.  Underwater acoustic ambient noise levels on the eastern Canadian continental shelf , 1990 .

[7]  W. Au,et al.  Acoustic interaction of humpback whales and whale-watching boats. , 2000, Marine environmental research.

[8]  D. Ross,et al.  Ship sources of ambient noise , 2005, IEEE Journal of Oceanic Engineering.

[9]  Arveson,et al.  Radiated noise characteristics of a modern cargo ship , 2000, The Journal of the Acoustical Society of America.

[10]  Riccardo Broglia,et al.  Prediction of hydrodynamic coefficients of ship hulls by high-order Godunov-type methods , 2009 .

[11]  S. Osher,et al.  A level set approach for computing solutions to incompressible two-phase flow , 1994 .

[12]  S. Wales,et al.  An ensemble source spectra model for merchant ship-radiated noise. , 2002, The Journal of the Acoustical Society of America.

[13]  Karel de Jong On the Optimization and the Design of Ship Screw Propellers with and without End Plates , 1991 .

[14]  Andrea Di Mascio,et al.  Analysis of the Flow Past a Fully Appended Hull with Propellers by Computational and Experimental Fluid Dynamics , 2011 .

[15]  D. Webb,et al.  ORIENTATION BY MEANS OF LONG RANGE ACOUSTIC SIGNALING IN BALEEN WHALES * , 1971, Annals of the New York Academy of Sciences.

[16]  J. Hildebrand,et al.  Underwater radiated noise from modern commercial ships. , 2012, The Journal of the Acoustical Society of America.

[17]  James A. Sethian,et al.  The Fast Construction of Extension Velocities in Level Set Methods , 1999 .

[18]  M. Trevorrow,et al.  Directionality and maneuvering effects on a surface ship underwater acoustic signature. , 2008, The Journal of the Acoustical Society of America.

[19]  S. Osher,et al.  Uniformly high order accurate essentially non-oscillatory schemes, 111 , 1987 .

[20]  J. Sethian,et al.  Fronts propagating with curvature-dependent speed: algorithms based on Hamilton-Jacobi formulations , 1988 .