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Point source stimulated acoustic radiation of cylindrical shells: Resonance and background fields

Rajabi, M ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.3813/AAA.918701
  3. Abstract:
  4. Objective: The method of wave function expansion in association with the spatial Fourier transform technique is adopted to study the steady-state sound radiation characteristics of a cylindrical component of infinite length subjected to an arbitrary time-harmonic on-surface concentrated radial drive. Method: Presenting the acoustical radiated coefficient as an exact function of modal accelerance function of the shell and following the classical Resonance Scattering Theory (RST), postulate that the radiated field can be synthesized as a superposition of the resonance response of the shell and a background signal within each partial wave. Utilizing the inherent background approach, we extracted the background (non-resonant) coefficients from the zero frequency limit of the three-dimensional (3-D) modal accelerance in the radiated coefficients for analogous liquid shells and the resonance components are isolated by the subtraction of these background coefficients from the radiated coefficients. Finally, the method of stationary phase is used to evaluate the formal integral expression for the total radiated pressure field and its resonant and background components in the frequency domain, for an observation point in the far-field. Results: The far-field modal and total radiated acoustic pressure, background field and resonance spectra and their directivities are investigated for a water submerged aluminium cylindrical shell with different thicknesses and the usefulness of the proposed approach is discussed in details. The results exhibit the notable existence of non-resonant field for thin shells, where the resonances associated with Lamb and fluid-born A-type waves are expected to appear. The overall validity of results is established by comparison with the data in the existing literature
  5. Keywords:
  7. Source: Acta Acustica united with Acustica ; Vol. 100, issue. 2 , 2014 , pp. 215-225 ; ISSN: 16101928
  8. URL: http://www.ingentaconnect.com/content/dav/aaua/2014/00000100/00000002/art00005?token=004d17823ff62237b76504c48666725533a4a2f2d31724d7c6a332b257d7241255e4e6b633142