Experimental approaches for the diagnostics of hydroacoustic problems in naval propulsion

Felli, Mario; Falchi, Massimo; Dubbioso, Giulio

doi:10.1016/j.oceaneng.2015.06.049

Cited by 19 publications

(6 citation statements)

References 37 publications

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“…In this section the major sources of noise populating the propeller wake are identified through the Lamb vector, which is the cross product of the vorticity and velocity vectors, , and appears as a source in the Powell acoustic analogy (Powell 1964). For more details about Powell's vortex sound theory the reader is referred also to Felli, Falchi & Dubbioso (2015).…”

Section: Resultsmentioning

confidence: 99%

“…A more extensive discussion dealing with the separation method, together with examples of practical implementations of the technique, are reported by Felli et al. (2014, 2015).…”

Section: Resultsmentioning

confidence: 99%

“…Then, they are anti-transformed from the wavelet to the physical space to obtain separated sound and pseudo-sound pressure fluctuation signals. A more extensive discussion dealing with the separation method, together with examples of practical implementations of the technique, are reported by Felli et al (2014Felli et al ( , 2015.…”

Section: Comparisons With the Experimentsmentioning

confidence: 99%

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Hydroacoustic analysis of a marine propeller using large-eddy simulation and acoustic analogy

et al. 2022

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The acoustic analogy is adopted to characterise the signature of a seven-bladed submarine propeller, relying on a high-fidelity large-eddy simulation, performed on a computational grid consisting of 840 million points. Results demonstrate that the nonlinear terms of the Ffowcs-Williams and Hawkings equation quickly become dominant moving away from the propeller along the direction of its wake development. While the linear terms experience a decay moving downstream, the nonlinear terms grow in the near wake, as a result of the development of wake instability. In particular, this growth affects frequencies lower than the blade frequency. Therefore, the acoustic signature of the propeller is mainly tonal in the near field only, due to the thickness and loading components of noise from the surface of the propeller and the periodic perturbation caused by its tip vortices. They develop instability at a faster rate, compared with the hub vortex, triggering the process of energy cascade towards higher frequencies and contributing in this way to broadband noise.

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Section: Resultsmentioning

confidence: 99%

“…A more extensive discussion dealing with the separation method, together with examples of practical implementations of the technique, are reported by Felli et al. (2014, 2015).…”

Section: Resultsmentioning

confidence: 99%

Section: Comparisons With the Experimentsmentioning

confidence: 99%

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Hydroacoustic analysis of a marine propeller using large-eddy simulation and acoustic analogy

et al. 2022

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“…Felli et al [ 18 ] presented a pioneering application of tomographic particle image velocimetry (tomographic PIV) for the hydrodynamic and hydroacoustic analysis of a marine propeller. Felli et al [ 19 ] review two “unconventional” approaches to address the diagnostics, analysis and solution of hydroacoustic problems in naval engineering experimentally. The first approach, based on direct pressure fluctuation measurements combined with detailed flow.…”

Section: Introductionmentioning

confidence: 99%

Numerical solution and experimental investigation for hydro-acoustic analysis and noise reduction assessment of ship ducted propeller

Alizadeh,

Abbaspour,

Mohseni Arasteh

et al. 2024

Heliyon

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“…At the same time, cutting-edge acoustic field detection techniques have been developed recently and tested to address acoustic problems using laboratory-scale experimental devices. Among others, Felli, Falchi & Dubbioso (2015) performed a detailed investigation into the relation between the coherent structures present in the wake of a model-scale ship propeller and acoustic sources, through a combined use of tomographic particle image velocimetry (PIV) and Powell's acoustic analogy. Specifically, the authors showed the importance of the wake on the overall noise produced by the rotor.…”

Section: Introductionmentioning

confidence: 99%

Scaling properties of the Ffowcs-Williams and Hawkings equation for complex acoustic source close to a free surface

Cianferra

Armenio

2021

J. Fluid Mech.

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We perform a scaling analysis of the terms composing the Ffowcs-Williams and Hawkings (FWH) equation, which rules the propagation of noise generated by a rigid body in motion. Our analysis extends the seminal work of Lighthill (Proc. R. Soc. Lond. A, vol. 211, 1952, pp. 564–587) and the dimensional analysis of classical sources (monopole, dipole and quadrupole) considering all the FWH integral terms. Scaling properties are analysed in light of perfect/imperfect similarity when laboratory-scale data are used for full-scale predictions. As a test case we consider a hydrodynamic example, namely a laboratory-scale ship propeller. The data, obtained numerically in a previous study, were post-processed according to the scaling analysis presented herein. We properly scale the speed of sound to obtain perfect similarity and quantify the error with respect to the imperfect scaling. Imperfect similarity introduces errors in the acoustic response related both to the linear terms and to the nonlinear terms, the latter of great importance when the wake is characterized by robust and organized vorticity. Successively, we analyse the effect of a free surface, often present in hydrodynamic applications. We apply the method of images to the FWH equation. The free surface may generate a frequency-dependent constructive/destructive interference. The analysis of an archetypal acoustic field (monopole) provides robust explanation of these interference effects. Finally, we find that imperfect similarity and the absence of a free surface may introduce errors when model-scale data are used to obtain the full-scale acoustic pressure. The error is small for microphones placed in the near field and becomes relevant in the far field because of the nonlinear terms.

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Experimental approaches for the diagnostics of hydroacoustic problems in naval propulsion

Cited by 19 publications

References 37 publications

Hydroacoustic analysis of a marine propeller using large-eddy simulation and acoustic analogy

Hydroacoustic analysis of a marine propeller using large-eddy simulation and acoustic analogy

Numerical solution and experimental investigation for hydro-acoustic analysis and noise reduction assessment of ship ducted propeller

Scaling properties of the Ffowcs-Williams and Hawkings equation for complex acoustic source close to a free surface

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