Scattering Of Wavepackets By A Flat Plate In The Vicinity Of A Turbulent Jet

dc.creatorCavalieri A.V.G.
dc.creatorJordan P.
dc.creatorWolf W.R.
dc.creatorGervais Y.
dc.date2014
dc.date2015-06-25T17:56:21Z
dc.date2015-11-26T14:44:01Z
dc.date2015-06-25T17:56:21Z
dc.date2015-11-26T14:44:01Z
dc.date.accessioned2018-03-28T21:52:32Z
dc.date.available2018-03-28T21:52:32Z
dc.identifier
dc.identifierJournal Of Sound And Vibration. Academic Press, v. 333, n. 24, p. 6516 - 6531, 2014.
dc.identifier0022460X
dc.identifier10.1016/j.jsv.2014.07.029
dc.identifierhttp://www.scopus.com/inward/record.url?eid=2-s2.0-84903901050&partnerID=40&md5=1b6e82f7fea1d3d0aec01d235cddaef4
dc.identifierhttp://www.repositorio.unicamp.br/handle/REPOSIP/87014
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/87014
dc.identifier2-s2.0-84903901050
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1251940
dc.descriptionWe present an investigation of the acoustic scattering due to the presence of a flat plate in the vicinity of a turbulent subsonic jet. Experiments have been performed to measure changes in the velocity and sound fields for Mach numbers ranging from 0.4 to 0.6, and for distances between the plate and the jet axis ranging from 1 to 2 jet diameters. Results show only very slight changes in the mean flow induced by the plate, and no differences in the velocity fluctuation amplitudes on the jet centreline, suggesting that wave-packet models derived for jets without installation effects may be representative of the installed case, at least for the jet-plate distances considered here. The acoustic results, on the other hand, include a significant increase in the low-frequency sound radiation, and phase opposition between the shielded and unshielded sides of the plate. There is an exponential decay of the scattered sound with increasing jet-plate distance, suggesting that low-frequency radiation is due to the scattering of evanescent hydrodynamic wavepackets in the jet near field. To model this phenomenon, we calculate sound generation from wave-packet sources in two ways: on one hand we use a tailored Greens function that accounts for the presence of a semi-infinite, rigid flat plate; and, on the other, we solve numerically the Helmholtz equation, with boundary conditions representative of a finite flat plate, using a fast multipole boundary element method. In agreement with the experimental measurements, numerical calculations capture the phase opposition between shielded and unshielded sides, and the scattered sound depends exponentially on the position of the plate. This exponential dependence is related to non-compact effects associated with wavepackets, as compact sources would lead to an algebraic dependence. Acoustic pressure directivities computed for the finite and semi-infinite flat plates agree well where acoustic reflection and diffraction from the trailing edge of the plates are concerned. However, additional diffraction effects associated with the leading and lateral edges of the finite plate, and which take the form of multiple lobes in the directivity, are illustrated by the comparison. As the plate dimensions are increased, i.e. the Helmholtz number is increased, the solution approaches that obtained for the semi-infinite plate.
dc.description333
dc.description24
dc.description6516
dc.description6531
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dc.languageen
dc.publisherAcademic Press
dc.relationJournal of Sound and Vibration
dc.rightsfechado
dc.sourceScopus
dc.titleScattering Of Wavepackets By A Flat Plate In The Vicinity Of A Turbulent Jet
dc.typeArtículos de revistas


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