Hybrid passive/active absorbers for flow ducts

Galland, Marie‐Annick; Mazeaud, Benoit; Sellen, Nadine

doi:10.1016/j.apacoust.2004.09.007

Cited by 55 publications

(53 citation statements)

References 9 publications

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“…In the literature, the control actuator is usually an extrinsic electrodynamic loudspeaker separated from the passive material by an air gap. In this configuration, the control strategy is to create a pressure release condition on the rear face of the passive material in order to maximize the viscous dissipation in it 1,2 or to cancel the reflected wave behind the passive material. 3,4 Other research has considered an active component imbedded into the passive material in the form of a piezoelectric actuator [5][6][7][8] to create "adaptive" or "smart" foams.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of a smart foam sound absorber

Leroy

Berry

Herzog

et al. 2011

The Journal of the Acoustical Society of America

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This article presents the experimental implementation and results of a hybrid passive/active absorber (smart foam) made up from the combination of a passive absorbent (foam) and a curved polyvinylidene fluoride (PVDF) film actuator bonded to the rear surface of the foam. Various smart foam prototypes were built and tested in active absorption experiments conducted in an impedance tube under plane wave propagation condition at frequencies between 100 and 1500 Hz. Three control cases were tested. The first case used a fixed controller derived in the frequency domain from estimations of the primary disturbance at a directive microphone position in the tube and the transfer function between the control PVDF and the directive microphone. The two other cases used an adaptive time-domain feedforward controller to absorb either a single-frequency incident wave or a broadband incident wave. The non-linearity of the smart foams and the causality constraint were identified to be important factors influencing active control performance. The effectiveness of the various smart foam prototypes is discussed in terms of the active and passive absorption coefficients as well as the control voltage of the PVDF actuator normalized by the incident sound pressure.

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Section: Introductionmentioning

confidence: 99%

Experimental study of a smart foam sound absorber

Leroy

Berry

Herzog

et al. 2011

The Journal of the Acoustical Society of America

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“…Lee et al 8 demonstrated some experimental results obtained with a hybrid concept involving a double-plate panel with a porous material and active control. The LMFA, Centre Acoustique, at Ecole Centrale de Lyon has developed over the last ten years a design of hybrid broadband absorbing liner which combines the passive properties of absorbent materials and active control 9 . The widespread design of such a hybrid structure is still an open topic, because we should choose the appropriate elastic plate and porous material, their parameters, and consider the optimal value of the secondary sound sources.…”

Section: Introductionmentioning

confidence: 99%

A plane wave study for improving acoustical performance of double wall systems using an active-passive method

Sitel¹,

Galland²,

Chen³

2009

Noise Control Eng. J.

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Finite multilayer structures are widely used in many engineering applications for increasing the sound absorption and for reducing the sound transmission. These so-called 'double wall system' is made up of two elastic plates and a core such as an air gap or highly-dissipative media like poroelastic materials. Such passive panels are efficient enough at medium and high frequencies but exhibit a lack of performance at low frequency, where resonance inherent to the layer distribution occurs. This paper presents a double wall system combined passive and active means. Passive panels with absorbent materials located in the emission side are used to increase absorption for a wide frequency range. Piezoelectric patches are added to the active panel and behave as a secondary vibrational source, ensuring high performance at low and/or resonance frequencies. The analytical and numerical simulations in Matlab are completed. At last, the result of experiment carried out in the Matisse set-up proposed by LMFA is in good agreement with the simulation. © 2009 Institute of Noise Control Engineering.

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“…The first strategy imposes a zero pressure on the back surface of the porous layer. [1][2][3][4][5][6][7] The second strategy consists in controlling the surface impedance of the active surface in order to cancel the reflected sound wave. [8][9][10][11][12] These two strategies have proved to be efficient for a broad frequency range but result in a weight and space penalty that may limit their application in industrial sectors such as aerospace.…”

Section: Introductionmentioning

confidence: 99%

Three dimensional finite element modeling of smart foam

Leroy

Atalla

Berry

et al. 2009

The Journal of the Acoustical Society of America

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The "smart foam" concept and design originate from the combination of the passive dissipation capability of foam in the medium and high frequency ranges and the active absorption ability of piezoelectric actuator (generally polyvinylidene fluoride) in the low frequency range. This results into a passive/active absorption control device that can efficiently operate over a broad range of frequencies. In this paper, a full three dimensional finite element model of smart foam is presented including its experimental validation. The modeling tool uses quadratic poroelastic elements, as well as elastic, fluid, and piezoelectric elements. The weak integral formulation of the different media involved is presented with the associated coupling conditions. A simplified orthotropic model of poroelastic media is presented. To validate the developed model, a prototype of a smart foam has been realized and its passive absorption and radiation measured in an impedance tube and compared to predictions. The experimental validation demonstrates the validity of the model. This modeling tool constitutes a general platform to simulate and optimize various configurations of smart foams.

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Hybrid passive/active absorbers for flow ducts

Cited by 55 publications

References 9 publications

Experimental study of a smart foam sound absorber

Experimental study of a smart foam sound absorber

A plane wave study for improving acoustical performance of double wall systems using an active-passive method

Three dimensional finite element modeling of smart foam

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