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

Ianniello, S.; Muscari, Roberto; Mascio, Andrea Di

doi:10.1007/s00773-013-0236-z

Cited by 61 publications

(25 citation statements)

References 17 publications

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“…The trace of the tip vortex-associated perturbation has a dipolar pattern centered in the vortex core. A similar pattern has been shown in Ianniello et al (2013) for the pressure field around a propeller tip vortex. The hydrodynamic pressure perturbation reduces dramatically moving inward along the trace of the trailing wake and, then, increases suddenly in the hub vortex region, where it presents again a dipolar pattern with inverted sign relatively to the corresponding tip sections.…”

Section: Comparison Between Velocity and Pressure Distributionssupporting

confidence: 83%

A novel approach for the isolation of the sound and pseudo-sound contributions from near-field pressure fluctuation measurements: analysis of the hydroacoustic and hydrodynamic perturbation in a propeller-rudder system

2013

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The main scope of the present work is to investigate the mechanisms underlying the hydroacoustic and hydrodynamic perturbations in a rudder operating in the wake of a free running marine propeller. The study consisted of detailed near-field pressure fluctuation measurements which were acquired on the face and back surfaces of the rudder, at different deflection angles. To this aim, a novel wavelet-filtering procedure was applied to separate and analyze distinctly the acoustic and hydrodynamic components of the recorded near-field pressure signals. The filtering procedure undertakes the separation of intermittent pressure peaks induced by the passage of eddy structures, interpreted as pseudo-sound, from homogenous background fluctuations, interpreted as sound. The use of wavelet in the filtering procedure allows to overcome the limitations of the earlier attempts based on frequency (wave number) band-pass filtering, retrieving the overall frequency content of both the acoustic and the hydrodynamic components and returning them as independent signals in the time domain. Acoustic and hydrodynamic pressure distributions were decomposed harmonically and compared to the corresponding topologies of the vorticity field, derived from earlier LDV measurements performed by Felli and Falchi (Exp Fluids 51(5):1385-1402, 2011. The study highlighted that the acoustic perturbation is mainly correlated with the unsteady load variations of the rudder and to the shear layer fluctuations of the propeller streamtube. Conversely, the dynamics of the propeller tip and hub vortices underlies the hydrodynamic perturbation.

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Section: Comparison Between Velocity and Pressure Distributionssupporting

confidence: 83%

A novel approach for the isolation of the sound and pseudo-sound contributions from near-field pressure fluctuation measurements: analysis of the hydroacoustic and hydrodynamic perturbation in a propeller-rudder system

2013

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“…The trace of the tip vortex-associated perturbation has a dipolar pattern centered in the vortex core. A similar pattern has been shown in Ianniello et al (2014) for the pressure field around a propeller tip vortex. The hydrodynamic pressure perturbation reduces dramatically moving inward along the trace of the trailing wake and, then, increases suddenly in the hub vortex region, where it presents again a dipolar pattern with inverted sign relatively to the corresponding tip sections.…”

Section: Hydroacoustic Analysis Of a Rudder Operating In The Wake Of supporting

confidence: 70%

“…Noise is mostly induced by the dynamics of the propeller vortical structures (Felli et al, 2011;Ianniello et al, 2014) and by the blade interaction with the hull wake. These phenomena are fully three dimensional, thus requiring the use of volumetric techniques, possibly time resolved, to resolve the inflow quantities representative of the source strength.…”

Section: Direct Approachmentioning

confidence: 99%

“…Indirect approach: The main idea behind this approach is to establish a direct connection between the hydro-acoustics problem and the flow phenomena at the origin of noise generation (see Jordan and Gervais, 2008), similarly to what is done by Computational Hydro-Acoustics (CHA) when based on the solution of the fully 3D unsteady Navier-Stokes equations (Ianniello et al, 2014). Unlike in the direct approach, the solution of the hydro-acoustic problem is, then, relied indirectly on quantitative field measurements able to fully describe the unsteady flow behavior and on the application of acoustic analogies in which the source term is formulated in terms of vorticity (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Experimental approaches for the diagnostics of hydroacoustic problems in naval propulsion

2015

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“…Meanwhile, in the view point of far-field radiation noise, turbulent-induced quadrupole noise term has usually been neglected to reduce computational cost [1]. Moreover, it has recently been found that the turbulent-induced noise is also important to understand characteristics of overall noise in far-field [3].…”

Section: Introductionmentioning

confidence: 99%

Turbulent-Induced Noise around a Circular Cylinder using Permeable FW-H Method

Choi¹,

Hong²,

Song³

et al. 2014

J. Korean Soc. Mar. Environ. Saf.

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Varieties of research on turbulent-induced noise are conducted with combinations of acoustic analogy methods and computational fluid dynamic methods to analyse efficiently and accurately. Application of FW-H acoustic analogy without turbulent noise is the most popular method due to its calculation cost. In this paper, turbulent-induced noise is predicted using RANS turbulence model and permeable FW-H method. For simplicity, noise from 2D cylinder is examined using three different methods: direct method of RANS, FW-H method without turbulent noise and permeable FW-H method which can take into account of turbulent-induced noise. Turbulent noise was well predicted using permeable FW-H method with same computational cost of original FW-H method. Also, ability of permeable FW-H method to predict highly accurate turbulent-induced noise by applying adequate permeable surface is presented. The procedure to predict turbulentinduced noise using permeable FW-H is established and its usability is shown.

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

Cited by 61 publications

References 17 publications

A novel approach for the isolation of the sound and pseudo-sound contributions from near-field pressure fluctuation measurements: analysis of the hydroacoustic and hydrodynamic perturbation in a propeller-rudder system

A novel approach for the isolation of the sound and pseudo-sound contributions from near-field pressure fluctuation measurements: analysis of the hydroacoustic and hydrodynamic perturbation in a propeller-rudder system

Experimental approaches for the diagnostics of hydroacoustic problems in naval propulsion

Turbulent-Induced Noise around a Circular Cylinder using Permeable FW-H Method

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