A source level model for propeller blade rate radiation for the world's merchant fleet

Gray, Leslie M.; Greeley, David S.

doi:10.1121/1.2003979

Cited by 19 publications

(25 citation statements)

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“…This is a reasonable depth-weighting approximation to the observed cavitation volumes reported in the literature. 7,13,16 A comparison of the ''upper quadrant propagation'' function ͓Fig. 2͑b͔͒ with the point-source propagation spectrogram ͓Fig.…”

Section: Measurement and Processing Methodologymentioning

confidence: 99%

“…Figure 1 shows a spectrogram of the ship-radiated noise for a specific ship along with the pointsource transmission loss computed along the source-receiver track for that ship. The specific example shown is a large tanker ͑the SHINOBU͒ with a 14.6-m draft that passed by the sonobuoy with a CPA of 1090 m. The source depth for the calculation, 7 m, was based on a formula provided by Gray and Greeley, 13,14 which estimates the center of the cavitation volume to be below the top of the propeller blade arc by an amount equal to 15 % of the propeller diameter. There are two dominant features in the transmission loss plot of Fig.…”

Section: Measurement and Processing Methodologymentioning

confidence: 99%

“…This volume varies in a cyclic fashion, reaching a peak as each propeller blade nears the top of its rotation. 2,3 Much of this knowledge is summarized in the texts by Ross, 4 Blake, 5 and Breslin and Anderson. 6 Models for the hydrodynamic processes related to the generation of the cavitation volumes and the resulting pressure fields have been developed.…”

Section: Introductionmentioning

confidence: 99%

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An ensemble source spectra model for merchant ship-radiated noise

Wales

Heitmeyer

2002

The Journal of the Acoustical Society of America

184

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This paper presents an evaluation of the classical model for determining an ensemble of the broadband source spectra of the sound generated by individual ships and proposes an alternate model to overcome the deficiencies in the classical model. The classical model, proposed by Ross [Mechanics of Underwater Noise (Pergamon, New York, 1976)] postulates that the source spectrum for an individual ship is proportional to a baseline spectrum with the constant of proportionality determined by a power-law relationship on the ship speed and length. The model evaluation, conducted on an ensemble of 54 source spectra over a 30-1200-Hz to 1200-Hz frequency band, shows that this assumption yields large rms errors in the broadband source level for the individual ships and significantly overestimates the variability in the source level across the ensemble of source spectra. These deficiencies are a consequence of the negligible correlation between the source level and the ship speed and the source level and the ship length. The alternate model proposed here represents the individual ship spectra by a modified rational spectrum where the poles and zeros are restricted to the real axis and the exponents of the terms are not restricted to integer values. An evaluation of this model on the source spectra ensemble indicates that the rms errors are significantly less than those obtained with any model where the frequency dependence is represented by a single baseline spectrum. Furthermore, at high frequencies (400 to 1200 Hz), a single-term rational spectrum model is sufficient to describe the frequency dependence and, at the low frequencies (30 to 400 Hz), there is only a modest reduction in the rms error for a higher order model. Finally, a joint probability density on the two parameters of the single term model based on the measured histograms of these parameters is proposed. This probability density provides a mechanism for generating an ensemble of ship spectra.

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Section: Measurement and Processing Methodologymentioning

confidence: 99%

Section: Measurement and Processing Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An ensemble source spectra model for merchant ship-radiated noise

Wales

Heitmeyer

2002

The Journal of the Acoustical Society of America

184

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“…Sperm whale clicks occurred in trains of broadband clicks with peak energy in 1-20 kHz and inter click intervals between 0.5 and 2 s, which was usually stable over several consecutive clicks. It is known that the sound generated by ships contains a broadband component caused by the collapse of cavitation voids generated as the blade passes through the top of its cycle of rotation [10,11]. Ship generated sound also consists of a narrow-band component, which was not addressed here.…”

Section: Description Of Datamentioning

confidence: 98%

Real-time acoustic classification of sperm whale clicks and shipping impulses from deep-sea observatories

Zaugg¹,

Schaar²,

Houégnigan³

et al. 2010

Applied Acoustics

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“…Source levels for ship traffic range from 150 dB for small fishing vessels to 195 dB for super tankers [6], [9]. Peak spectral levels for shipping traffic occur at less than 500 Hz with substantial tonal contributions as low as 10 Hz [10].…”

Section: Literature Reviewmentioning

confidence: 99%

Characteristics of underwater ambient noise at a proposed tidal energy site in puget sound

Bassett

Thomson

Polagye

2010

Oceans 2010 MTS/Ieee Seattle

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Ambient underwater acoustics data are presented for one year at a potential tidal energy site in Admiralty Inlet, WA (USA) with maximum currents exceeding 3 m/s. The site, at a depth of approximately 60 meters, is located near shipping lanes, a local ferry route, and a transit area for many cetacean species. A key finding is that the statistical distribution of total sound pressure levels are dependent on tidal currents at the site. Pseudosound, cobbles shifting on the sea bed, and vibrations induced by forces on the equipment are possible explanations. Non-propagating turbulent pressure fluctuations, termed pseudosound, can mask ambient noise, especially in highly energetic environments suitable for tidal energy development. A statistical method identifies periods during which changes in the mean and standard deviation of the one-third octave band sound pressure levels are statistically significant and thus suggestive of pseudosound contamination. For each deployment, recordings with depth averaged tidal currents greater than 1 m/s are found to be contaminated, and only recordings with currents below this threshold are used in the subsequent ambient noise analysis.Mean total sound pressure levels (0.156 -30 kHz) over all recordings are 117 dB re 1µPa. Total sound pressure levels exceed 100 dB re 1µPa 99% of the time and exceed 135 dB re 1µPa 4% of the time. Commercial shipping and ferry traffic are found to be the most significant contributors to ambient noise levels at the site, with secondary contributions from rain, wind, and marine mammal vocalizations. Post-processed data from an AIS (Automatic Identification System) receiver is used to determine the location of ships during each recording. Referencing 368 individual recordings with the distance between the ferry and the site obtained from AIS data, the source level of the ferry is estimated to be 179 ± 4 dB re 1µPa at 1m with a logarithmic spreading loss coefficient of 18.

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A source level model for propeller blade rate radiation for the world's merchant fleet

Cited by 19 publications

References 0 publications

An ensemble source spectra model for merchant ship-radiated noise

An ensemble source spectra model for merchant ship-radiated noise

Real-time acoustic classification of sperm whale clicks and shipping impulses from deep-sea observatories

Characteristics of underwater ambient noise at a proposed tidal energy site in puget sound

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