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The impedance boundary condition for acoustics in swirling ducted flow
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Masson, Vianney , Mathews, James , Moreau, Stéphane, Posson , Hélène and Brambley, Edward J. (James) (2018) The impedance boundary condition for acoustics in swirling ducted flow. Journal of Fluid Mechanics, 849 . pp. 645-675. doi:10.1017/jfm.2018.429
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WRAP-impedance-boundary-condition-acoustics-swirling-flow-Bramble-2018.pdf - Accepted Version - Requires a PDF viewer. Download (913Kb) | Preview |
Official URL: https://doi.org/10.1017/jfm.2018.429
Abstract
The acoustics of a straight annular lined duct containing a swirling mean flow is considered. The classical Ingard–Myers impedance boundary condition is shown not to be correct for swirling flow. By considering behaviour within the thin boundary layers at the duct walls, the correct impedance boundary condition for an infinitely thin boundary layer with swirl is derived, which reduces to the Ingard–Myers condition when the swirl is set to zero. The correct boundary condition contains a spring-like term due to centrifugal acceleration at the walls, and consequently has a different sign at the inner (hub) and outer (tip) walls. Examples are given for mean flows relevant to the interstage region of aeroengines. Surface waves in swirling flows are also considered, and are shown to obey a more complicated dispersion relation than for non-swirling flows. The stability of the surface waves is also investigated, and as in the non-swirling case, one unstable surface wave per wall is found.
| Item Type: | Journal Article | |||||||||||||||
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| Subjects: | T Technology > TL Motor vehicles. Aeronautics. Astronautics | |||||||||||||||
| Divisions: | Faculty of Science > Mathematics Faculty of Science > WMG (Formerly the Warwick Manufacturing Group) |
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| Library of Congress Subject Headings (LCSH): | Airplanes -- Turbojet engines, Jet planes -- Noise | |||||||||||||||
| Journal or Publication Title: | Journal of Fluid Mechanics | |||||||||||||||
| Publisher: | Cambridge University Press | |||||||||||||||
| ISSN: | 0022-1120 | |||||||||||||||
| Official Date: | 25 August 2018 | |||||||||||||||
| Dates: |
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| Volume: | 849 | |||||||||||||||
| Page Range: | pp. 645-675 | |||||||||||||||
| DOI: | 10.1017/jfm.2018.429 | |||||||||||||||
| Status: | Peer Reviewed | |||||||||||||||
| Publication Status: | Published | |||||||||||||||
| Access rights to Published version: | Restricted or Subscription Access | |||||||||||||||
| RIOXX Funder/Project Grant: |
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