The propagation and attenuation of sound in lined ducts containing uniform or “plug” flow

Tester, Brian J.

doi:10.1016/s0022-460x(73)80102-6

Cited by 206 publications

(99 citation statements)

References 26 publications

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“…An other conclusion is the fact that the axial wave number of the instability (if present) is very sensitive for variations in δ, in particular when δ is small, confirming the earlier conclusions by Tester [3] based on a similar but more restricted exploration of the present problem.…”

Section: Resultssupporting

confidence: 87%

“…The aero-acoustics community followed them and now the Ingard-Myers boundary condition is the state-of-the-art for this kind of mean flows. However, more refined analyses [3][4][5][6] as well as numerical time-domain results [7][8][9] indicate that the wall vortex sheet along the lined wall may be spatially unstable. This instability is to be interpreted as related to the Kelvin-Helmholtz instability [10] inherent to vortex sheets separating two inviscid fluids of different velocity.…”

Section: Introductionmentioning

confidence: 99%

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Spatial Instability of Boundary Layer Along Impedance Wall

Rienstra

Vilenski

2008

14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference)

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A numerical analysis is made of the hydro-acoustical spatial instability, apparently occurring in a mean flow with thin boundary layer along a locally reacting lined duct wall. This problem is of particular interest because unstable behaviour of liner and mean flow has been observed only very rarely.It is found that this instability quickly disappears for increasing boundary layer thickness. Specifically, for boundary-layer-thickness based Helmholtz numbers ωδ/c 0 of the order of 0.1 the growth rate vanishes and the instability disappears. This corresponds to very thin boundary layers for practical values of frequencies that occur in aero-engine applications, which is in turn in good agreement with the fact that in industrial practice no instabilities are observed.For low duct-radius based Helmholtz numbers (∼ 1), the instability exists for rather large values of δ as an almost neutrally stable wave. This is qualitatively in good agreement with the experimental observations of Ronneberger and Auregan.It is shown by a Rayleigh-type stability criterion that impedance related hydrodynamic instabilities of temporal type do not occur for mean flows with strictly negative 2nd derivative (the usual situation).

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Section: Resultssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Spatial Instability of Boundary Layer Along Impedance Wall

Rienstra

Vilenski

2008

14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference)

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“…However, there have been a number of studies in recent years, which have identified problems with Myers condition resulting from the modelling assumptions. There are doubts as to whether the Myers model deals correctly with hydrodynamic modes in the boundary layer [19,20,21]. Since the boundary condition is the limit of an infinitely thin boundary layer, or the boundary layer being collapsed into a vortex sheet, when applied with slipping mean flow it may exhibit an instability comparable to the Kelvin-Helmholtz free-shear-layer instability.…”

Section: A Wem-based Methodology For Computing the Propagation In A Lmentioning

confidence: 99%

A wave expansion method for acoustic propagation in lined flow ducts

O’Reilly

2015

Applied Acoustics

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Acoustic liners are used extensively in engineering applications, particularly in aero-engines and automotive exhaust systems. In this paper, a flow impedance boundary conditions is introduced into the wave expansion method with the aim of providing an efficient methodology for computing the acoustic propagation through a lined duct with flow. For a potential flow, the boundary layer and the lined wall are included in the discretisation scheme by the Myers flow impedance boundary condition. The acoustic propagation through a flow-impedance tube is computed in order to validate the implementation of the impedance boundary condition in this scheme. The results show that this computationally light methodology provides generally good agreement with the experimental data.

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“…In their design strategy, cavity structures are fitted with a micro-perforated cover sheet, so that the wall impedance equals the Cremer value at one target frequency. The Cremer impedance for the plane wave in a circular wave guide is given by Tester [9] …”

Section: Compact Dissipative Silencers With a Cremer Wall Impedancementioning

confidence: 99%

“…The MPPs are used in two configurations; the first configuration aims at damping the plane wave mode, based on the work of Kabral and Åbom [7], and is designed to realize the so called Cremer impedance at a given target frequency. By adopting a wall impedance for optimal attenuation which was firstly described by Cremer [8] for rectangular ducts and later derived for circular ducts by Tester [9], extremely high damping can be achieved with very compact silencers as shown in Ref. [10].…”

Section: Introductionmentioning

confidence: 99%