Experimental assessment of an active (acoustic) liner prototype in an acoustic flow duct facility

Billon, Kévin; Bono, Emanuele De; Perez, Matthias; Salze, Édouard; Matten, Gaël; Gillet, Martin; Ouisse, Morvan; Volery, Maxime; Lissek, Hervé; Mardjono, Jacky; Collet, Manuel

doi:10.1117/12.2583099

Cited by 6 publications

(4 citation statements)

References 6 publications

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“…This boundary condition involves a first order spatial gradient, which hence implies nonlocality of the boundary reaction and non-reciprocity (as it is of first order). This operator has been implemented on a programmable boundary made up of electroacoustic resonators (ER), as described in [2,3,5] by piloting the electrical current i(s) in the speaker coil. Its expression in the Laplace domain is given in Eq.…”

Section: Plane Waves Attenuationmentioning

confidence: 99%

Advection Boundary Law for sound transmission attenuation of plane and spinning guided modes

De Bono,

Collet,

Salze

et al. 2024

Proceedings of the 10th Convention of the European Acoustics Association Forum Acusticum 2023

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Sound attenuation along a waveguide is a highly demanded research field, for applications ranging from heating and air-conditioning ventilation systems, to aircraft turbofan engines. Electroacoustic devices and digital control have provided the tools for crafting innovative liners where the boundary condition can be programmed. The most straightforward idea is to program classical local impedance operators. Nevertheless, it might be worthy to navigate off the beaten track, and try to target boundary operators which could never be physically produced by purely passive treatments. In this contribution, we focus the attention on a particular boundary law, called advective, as it possesses a convective character achieved thanks to the introduction of the first spatial derivative. After introducing such special boundary condition, we implement it on an electroacoustic liner and demonstrate its potentialities in enhancing the transmission loss in acoustic waveguides with flow. We present results for both plane and spinning modes attenuation. Numerical simulations and experimental implementations demonstrate the potential-

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Section: Plane Waves Attenuationmentioning

confidence: 99%

Advection Boundary Law for sound transmission attenuation of plane and spinning guided modes

De Bono,

Collet,

Salze

et al. 2024

Proceedings of the 10th Convention of the European Acoustics Association Forum Acusticum 2023

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“…The acoustic passive and active liners are technologies that have proved to successfully mitigate the duct-noise propagation [28,29]. On the one hand, the former act on a wide range of frequencies and do not require energy to operate.…”

Section: B Noise Propagationmentioning

confidence: 99%

“…An active liner consists of an array of electroacoustic cells, made by a loudspeaker (the actuator) placed in the center of the cell, and one or more microphones (the sensors) fitted around it. By controlling the electrical current in the loudspeaker coil with a programmable digital processor, it is possible to change the loudspeaker dynamics based on the microphone measurements and reproduce the desired relationship between the actuator displacement and local averaged pressure [29].…”

Section: B Noise Propagationmentioning

confidence: 99%

Development of the SmartAnswer Demonstrator: a Didactic Wind Tunnel for Aeroacoustic Applications

Tamaro

Zamponi

Schram

2022

28th AIAA/CEAS Aeroacoustics 2022 Conference

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A small didactic wind tunnel demonstrator has been designed and manufactured at the von Karman Institute for Fluid Dynamics to illustrate the physical principles at stake in flow-induced noise generation, offer an audible perception of the effectiveness of noise-mitigation strategies, and serve as a practical test bench for aeroacoustic education and research. Seven mitigation technologies are embedded in a single facility, which addresses the noise generation by an airfoil, noise propagation in a duct, and noise transmission through a flexible panel. A challenging objective of this facility was to offer a perceptible impression of various aeroacoustic noise mechanisms at low flow speeds and a live assessment of the effectiveness of the noisereduction technologies. Different approaches combining multiple microphones, advanced signal-processing techniques, and real-time audio feedback have been implemented to this end. The results establish that the demonstrator enables a clear perception of the effectiveness of the noise-mitigation technologies. The facility is also suitable for fast and inexpensive preliminary investigations of future noise-reduction concepts, taking advantage of rapid prototyping techniques.

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“…2 Despite the physiological time delay of the digital control, which can affect the passivity margins at high frequencies, 3 such ER strategy has demonstrated its efficiency for both room-modal equalization 4 and sound transmission mitigation in waveguides. [5][6][7][8][9] The model-inversion algorithm has also been extended to contemplate nonlinear target dynamics at low excitation levels. [10][11][12][13] In, 14 for the first time, a programmable liner involving the spatial derivative was realised by distributed electroacoustic devices.…”

Section: Introductionmentioning

confidence: 99%

Breaking the limitations of local impedance noise control: passivity, and scattering performances of the Advection Boundary Law

De Bono,

Collet,

Ouisse

2024

Active and Passive Smart Structures and Integrated Systems XVIII

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In the aim of attenuating noise transmission through air-ducts, research is prompted for overcoming the limitations of classical acoustic liners, especially in the aero-engines applications. The new generation of Ultra-High-By-Pass-Ratio (UHBR) turbofans while considerably reducing fuel consumption, increases noise pollution especially at lower frequencies because of their larger diameter, lower number of blades and rotational speed. Moreover, they present a shorter nacelle, leaving less available space for acoustic treatments. In case of simplified one-dimensional propagation, integral constraints exist which analytically define the limits of the scattering performances of reciprocal systems, such they are the local impedance liners, for a fixed length of the acoustic treatment along the duct. In this contribution, we analyse a special boundary condition breaking the reciprocity principle, and overcoming the limitations of locally reacting liners. We call it Advection Boundary Law as it introduces a convection on the boundary, responsible of non-reciprocal behaviour at grazing incidence, and of the enhancement of transmission loss with respect to pure locally-reacting resonators. Performances and passivity of such boundary law are numerically analysed first in grazing-incidence problems. The grazing-incidence problem is experimentally studied in a plane-wave acoustic waveguide lined by electroacoustic resonators which can be programmed to reproduce such advection boundary law.

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Experimental assessment of an active (acoustic) liner prototype in an acoustic flow duct facility

Cited by 6 publications

References 6 publications

Advection Boundary Law for sound transmission attenuation of plane and spinning guided modes

Advection Boundary Law for sound transmission attenuation of plane and spinning guided modes

Development of the SmartAnswer Demonstrator: a Didactic Wind Tunnel for Aeroacoustic Applications

Breaking the limitations of local impedance noise control: passivity, and scattering performances of the Advection Boundary Law

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