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Sound amplification at a rectangular T-junction with merging mean flows
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx). Beijing University of Aeronautics and Astronautics, China.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0001-7898-8643
2016 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 367, 69-83 p.Article in journal (Refereed) PublishedText
Abstract [en]

This paper reports a numerical study on the aeroacoustic response of a rectangular T-junction with merging mean flows. The primary motivation of the work is to explain the high sound amplification, recently seen experimentally, when introducing a small merging bias flow. The acoustic results are found solving the compressible Linearized Navier-Stokes Equations (LNSEs) in the frequency domain, where the base flow is first obtained using RANS with a k-epsilon turbulence model. The model predicts the measured scattering data well, including the amplitude and Strouhal number for the peak amplification, if the effect of eddy viscosity damping is included. It is found that the base flow changes significantly with the presence of a small bias flow. Compared to pure grazing flow a strong unstable shear layer is created in the downstream main duct starting from the T-junction trailing edge. This means that the main region of vortex-sound interaction is moved away from the junction to a downstream region much larger than the junction width. To analyze the sound amplification in this region Howe's energy corollary and the growth of acoustic density are used.

Place, publisher, year, edition, pages
Academic Press, 2016. Vol. 367, 69-83 p.
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-182763DOI: 10.1016/j.jsv.2015.12.042ISI: 000369059500005ScopusID: 2-s2.0-84957850378OAI: oai:DiVA.org:kth-182763DiVA: diva2:906132
Note

QC 20160223

Available from: 2016-02-23 Created: 2016-02-23 Last updated: 2016-03-24Bibliographically approved

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