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Aeroacoustics of rectangular T-junctions subject to combined grazing and bias flows: an experimental investigation
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0001-7898-8643
(English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568Article in journal (Other academic) Submitted
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-105697OAI: oai:DiVA.org:kth-105697DiVA: diva2:571685
Note

QS 2012

Available from: 2012-11-23 Created: 2012-11-23 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Aeroacoustic Characterization using Multiport Methods
Open this publication in new window or tab >>Aeroacoustic Characterization using Multiport Methods
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Noise is a major environmental pollutant, which can inict physical and psychologicalinjury. An important noise contribution stems from aeroacousticsources, which are found in e.g., ventilation ducts, engine exhaust systems andairplane engines.In this thesis, research methods for low Mach number aeroacoustic sourcesin ducts are developed. The basis of the methods is the ability to describe theintrinsic linear properties of the source as an N-port (multiport), where theoutput sound eld is related to the input sound eld and the generated soundeld, all consisting of plane waves. The methods presented are both numericaland experimental. The numerical method treats the passive properties, i.e.,scattering, attenuation and amplication of incident sound, while the experimentalmethod treats the active part (intrinsic sound generation) as well. Themethods are applied in the study of noise generation by a vortex mixer plate,placed in an airow of Mach 0.2, and in the study of acoustic-hydrodynamicinteraction in a T-junction of rectangular ducts.It is found that the accuracy of the experimental methods is signicantly increasedwhen the equations are over-determined, which is achieved by addingadditional microphones to the test rig. In the frequency range studied, themixer plate is found to generate less sound when made exible, without disturbingthe mixing quality.For the numerical method { based on the linearized Navier-Stokes equations,a model of the oscillation of the Reynolds stress (\turbulent damping")due to the acoustic eld is introduced. By comparing with experimental results,it is found that not using this model results in an over-prediction of theamplication at higher frequencies with several factors in magnitude, whileimplementing the model results in a much better agreement.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. vi, 66 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2012:76
Keyword
Aeroacoustics, Multiport, Experiments, Computational Aeroacoustics, Mixer Plate, T-junction.
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-105396 (URN)978-91-7501-563-7 (ISBN)
Public defence
2012-12-10, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research CouncilTrenOp, Transport Research Environment with Novel Perspectives
Note

QC 20121123

Available from: 2012-11-23 Created: 2012-11-20 Last updated: 2013-04-11Bibliographically approved

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Åbom, Mats

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