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Application of the point matching method to model circumferentially segmented non-locally reacting liners
KTH, Superseded Departments, Vehicle Engineering.
KTH, Superseded Departments, Vehicle Engineering.ORCID iD: 0000-0002-8474-8563
KTH, Superseded Departments, Vehicle Engineering.ORCID iD: 0000-0002-3826-3055
2001 (English)In: 7th AIAA/CEAS Aeroacoustics Conference and Exhibit, 2001Conference paper (Refereed)Text
Abstract [en]

Acoustic liners are widely used to attenuate sound waves inside the aircraft jet engines. Previous research has proved that segmenting the liner and the positioning of the liner segments affect the attenuation characteristics of the liner. The combined effect of circumferentially segmented and non-locally reacting liners received little attention. The aim of this work is to investigate these effects, and to compare the properties of circumferentially segmented duct liners with those of uniform liners, in order to identify any potential benefits of circumferentially segmented liners. A new technique is proposed here; the point-matching method. Briefly, it is a straightforward numerical method based on a closed form ansatz, which fulfils the governing equations and is matched to the boundary conditions point-wise. A code, previously developed for automobile applications, is used to obtain the wave numbers of the different modes, from which the transmission loss for each mode can be calculated at the desired range of frequencies. An infinite cylindrical duct of diameter 40 cms was chosen to apply different non-locally (bulk) reacting liner configurations on. It was found that the existence of hard surfaces in a lined duct and their arrangement greatly affect the behavior of each mode and the energy distribution among them.

Place, publisher, year, edition, pages
Keyword [en]
Aircraft jet engines, Attenuation characteristics, Automobile applications, Cylindrical ducts, Energy distributions, Governing equations, Point matching method, Potential benefits, Aeroacoustics, Jet engines, Ducts
National Category
Fluid Mechanics and Acoustics
URN: urn:nbn:se:kth:diva-180785ScopusID: 2-s2.0-84896890899OAI: diva2:896734
7th AIAA/CEAS Aeroacoustics Conference and Exhibit, 2001, 28 May 2001 through 30 May 2001, Maastricht

NR 20160222

Available from: 2016-01-22 Created: 2016-01-22 Last updated: 2016-02-22Bibliographically approved

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Elnady, T.Bodén, H.Glav, R.
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