Underwater measurement of narrowband sound power and directivity using Supersonic Intensity in Reverberant Environments

Andrew R. Barnard, Stephen A. Hambric, Julian D. Maynard

Research output: Contribution to journalArticle

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Abstract

A laboratory underwater acoustic measurement technique, Supersonic Intensity in Reverberant Environments (SIRE), is developed analytically and validated experimentally and numerically. Unlike standard free or diffuse field techniques, SIRE enables the measurement of narrowband sound power and directivity in an environment with inexact field conditions. The technique takes advantage of underwater vector sensors, measuring only acoustic pressure and the normal component of particle velocity/acceleration, and supersonic wavenumber filtering in the near field of a source. The result is outward-propagating acoustic waves separated from interfering incoming and/or evanescent waves. The SIRE technique was experimentally applied to monopole and dipole sources and the results are compared with theory and standard methods. SIRE is shown to accurately measure radiated sound power to within the limits of ANSI S12.51 and to accurately measure the directivity indices of simple sources to within ±3 dB. A coupled finite element/boundary element model of a point-driven, thin-walled cylinder is also developed to establish the limitations of the SIRE technique. The model results show that the measurement standoff distance should be less than the reciprocal of the largest wavenumber in the frequency band of interest. Furthermore, the maximum measurement grid spacing must be less than twice the standoff distance.

Original languageEnglish (US)
Pages (from-to)3931-3944
Number of pages14
JournalJournal of Sound and Vibration
Volume331
Issue number17
DOIs
StatePublished - Aug 13 2012

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Acoustics and Ultrasonics
  • Mechanical Engineering

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