Underwater Sound Characteristics of a Ship with Controllable Pitch Propeller
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jmse-10-00328-v2.pdf
Size
3.64 MB
Format
Adobe PDF
Checksum (MD5)
16d43733bcfc389577e65ff462921715
Author(s)
Zhu, Chenyang
Gaggero, Tomaso
Makris, Nicholas C.
Ratilal, Purnima
Date Issued
February 25, 2022
Publisher
Multidisciplinary Digital Publishing Institute
Citation
Journal of Marine Science and Engineering 10 (3): 328 (2022)
Version
Final published version
Abstract
The time-dependent spectral characteristics of underwater sound radiated by an ocean vessel has complex dependencies on ship machinery, propeller dynamics, hydrodynamics of ship exhaust and motion, as well as ship board activities. Here the underwater sound radiated by a ship equipped with a controllable pitch propeller (CPP) is analyzed and quantified via its (i) power spectral density for signal energetics, (ii) temporal coherence for machinery tonal sound, and (iii) spectral coherence for propeller amplitude-modulated cavitation noise. Frequency-modulated (FM) tonal signals are also characterized in terms of their frequency variations. These characteristics are compared for different propeller pitch ratios ranging from 20% to 82% at fixed propeller revolutions per minute (RPM). The efficacy and robustness of ship parameter estimation at different pitches are discussed. Finally, analysis of one special measurement is provided, when ship changes speed, propeller pitch and RPM over the duration of the measurement. The 50% pitch is found to be a crucial point for this ship about which tonal characteristics of its underwater radiated sound attain their peak values, while broadband sound and associated spectral coherences are at a minimum. The findings here elucidate the effects of pitch variation on underwater sound radiated by ships with controllable pitch propellers and has applications in ship design and underwater noise mitigation.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
Terms of Use
Creative Commons Attribution
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DOI of Published Version
https://doi.org/10.3390/jmse10030328
