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

Emanuele De Bono; Manuel Collet; Morvan Ouisse

doi:10.1117/12.3010433

9 May 2024 Breaking the limitations of local impedance noise control: passivity, and scattering performances of the Advection Boundary Law

Emanuele De Bono, Manuel Collet, Morvan Ouisse

Author Affiliations +

Proceedings Volume 12946, Active and Passive Smart Structures and Integrated Systems XVIII; 129461J (2024) https://doi.org/10.1117/12.3010433
Event: SPIE Smart Structures + Nondestructive Evaluation, 2024, Long Beach, California, United States

Abstract

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.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Emanuele De Bono, Manuel Collet, and Morvan Ouisse "Breaking the limitations of local impedance noise control: passivity, and scattering performances of the Advection Boundary Law", Proc. SPIE 12946, Active and Passive Smart Structures and Integrated Systems XVIII, 129461J (9 May 2024); https://doi.org/10.1117/12.3010433

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