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Nonlinear acoustics in a viscothermal boundary layer over an acoustic lining
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Petrie, Owen and Brambley, Edward J. (James) (2020) Nonlinear acoustics in a viscothermal boundary layer over an acoustic lining. AIAA Journal, 58 (2). pp. 673-686. doi:10.2514/1.J058180 ISSN 0001-1452.
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WRAP-nonlinear-acoustics-viscothermal-boundary-layer-lining-Brambley-2019.pdf - Accepted Version - Requires a PDF viewer. Download (1099Kb) | Preview |
Official URL: https://doi.org/10.2514/1.J058180
Abstract
Sound within aircraft engines can be 120dB-160dB, pushing the validity of linearized governing equations. Moreover, some components of sound within a visco-thermal mean flow boundary layer over an acoustic lining may be amplified by a factor of ~100 (~40dB) in a typical aircraft engine compared with the sound outside the boundary layer, which may be expected to trigger nonlinear effects within the boundary layer. This is in addition to the well-known nonlinear effects within the holes of the perforated lining facing sheet. This paper presents a mathematical investigation into the effects of weak nonlinearity on the acoustics within a thin parallel mean flow boundary layer in flow over an acoustic lining in a cylindrical duct. (This is the first investigation of nonlinear acoustics in a boundary layer flow over a non-rigid surface, to our knowledge.) The analysis combines the effects of sheared mean flow, viscosity, and nonlinearity into an effective impedance boundary condition. In certain cases, a surprisingly large acoustic streaming effect is found that escapes the mean flow boundary layer and pervades well out into the interior of the duct.
Item Type: | Journal Article | |||||||||
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Subjects: | Q Science > QA Mathematics Q Science > QC Physics T Technology > TA Engineering (General). Civil engineering (General) |
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Mathematics Faculty of Science, Engineering and Medicine > Engineering > WMG (Formerly the Warwick Manufacturing Group) |
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Library of Congress Subject Headings (LCSH): | Nonlinear acoustics, Aeroacoustics, Boundary layer, Acoustical engineering | |||||||||
Journal or Publication Title: | AIAA Journal | |||||||||
Publisher: | American Institute of Aeronautical and Astronautics | |||||||||
ISSN: | 0001-1452 | |||||||||
Official Date: | February 2020 | |||||||||
Dates: |
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Volume: | 58 | |||||||||
Number: | 2 | |||||||||
Page Range: | pp. 673-686 | |||||||||
DOI: | 10.2514/1.J058180 | |||||||||
Status: | Peer Reviewed | |||||||||
Publication Status: | Published | |||||||||
Access rights to Published version: | Restricted or Subscription Access | |||||||||
Copyright Holders: | Copyright © 2019 by the American Institute of Aeronautics and Astronautics | |||||||||
Date of first compliant deposit: | 18 September 2019 | |||||||||
Date of first compliant Open Access: | 19 November 2019 | |||||||||
Funder: | Royal Society, Trinity College, Cambridge | |||||||||
Grant number: | UF150695 | |||||||||
RIOXX Funder/Project Grant: |
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