Accession Number : ADA182518


Title :   Problems in Nonlinear Acoustics: Parametric Receiving Arrays, Focused Finite Amplitude Sound, & Noncollinear Tone-Noise Interactions


Descriptive Note : Annual summary rept. no. 2, 1 May 1986-1 Jul 1987


Corporate Author : TEXAS UNIV AT AUSTIN DEPT OF MECHANICAL ENGINEERING


Personal Author(s) : Hamilton, Mark F


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a182518.pdf


Report Date : 01 Jul 1987


Pagination or Media Count : 33


Abstract : Three projects are discussed in this report. (1) Parametric Receiving Arrays. This project is a theoretical investigation into the use of a parametric receiving array for directive measurements of noise radiated by ships in reverberant environments. The analysis is based on a Gaussian beam model that takes nearfield diffraction into account. The scattering of sound is also investigated. (2) Focused Finite Amplitude Sound. A numerical solution is used to investigate the combined effects of nonlinearity, diffraction, and absorption on sound that propagates through a focal region. The analysis yields time waveforms, axial propagation curves, spectral power distributions, and beams patterns. (3) Noncollinear Tone-Noise Interactions. The noncollinear interaction of a pure tone and a band of noise that propagate in different modes of a rectangular duct is investigated both experimentally and theoretically. Keywords: Nonlinear acoustics; Parametric array; Scattering of sound by sound; Focused sound; Waveguide; Noise.


Descriptors :   *ACOUSTIC ARRAYS , *PARAMETRIC DEVICES , ACOUSTIC ABSORPTION , ACOUSTIC SCATTERING , ACOUSTICS , BEAMS(RADIATION) , DIFFRACTION , DIRECTION FINDING , DUCTS , FOCUSING , MODELS , NEAR FIELD , NONLINEAR SYSTEMS , NUMERICAL ANALYSIS , POWER , RADIATED NOISE , RECTANGULAR BODIES , REVERBERATION , SHIP NOISE , SOLUTIONS(GENERAL) , SOUND , THEORY , TIME , WAVEFORMS , WAVEGUIDES , YIELD


Subject Categories : Acoustic Detection and Detectors
      Acoustics


Distribution Statement : APPROVED FOR PUBLIC RELEASE