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Communication Dans Un Congrès Année : 2020

Cost-efficient characterization of the aeroacoustic performance of micro-perforated wall-treatments in a wind tunnel

Résumé

Reduction of flow-induced noise constitutes a line of continuous research as acoustic standards are formulated considering more stringent criteria as well as further integrated end-user and eco-friendly factors. For instance, Turbulent Boundary Layer (TBL) constitutes a broadband noise source for an aircraft under cruise conditions that contributes to cabin noise between 500 Hz and 2 kHz. 1-3 Although passive methods may add additional weight and are accompanied by some degradation in high-lift / lowdrag performance, they continue to be developed due to their straight realizations in practical applications. Overall, low frequencies, which are predominantly transmitted, are difficult to control without the introduction of massive components. Acoustic liners, when optimized, are efficient to reduce noise propagation in low-speed flow ducts such as in exhaust silencers 4 or in high-speed flow ducts such as at the inlet of aircraft turbofans. 5 Their acoustic and aerodynamic properties in presence of grazing flow opens up several questions, especially how to maintain high dissipation performance while keeping low skin friction. 6 These dissipative wall treatments are typically made of perforated sheets rigidly-backed by an air cavity, a honeycomb core, or filled with porous or fibrous materials. Structures composed of microperforated panels (MPPs) have become an alternative solution to porous materials since they can be used in hostile environments 7 and do not introduce added mass. These devices are resonance absorbers composed of a panel with sub-millimetric holes backed by a cavity. 8,9 Optimal performance are achieved by a proper selection of the panel thickness, of the size and shape of the perforations, of the perforation ratio (or porosity) and of the cavity depth. The goals are to increase the viscous losses through the apertures that dissipate the acoustic energy around the Helmholtz resonance, and to obtain high absorption values over a broad bandwidth. The advantages come from the fact that they are light compact devices that can be fitted in the small spaces available, for instance within sidewalls. They can easily be
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Dates et versions

hal-03430599 , version 1 (16-11-2021)

Identifiants

  • HAL Id : hal-03430599 , version 1

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Cédric Maury, Teresa Bravo, Daniel Mazzoni, M Amielh, Laurence Pietri. Cost-efficient characterization of the aeroacoustic performance of micro-perforated wall-treatments in a wind tunnel. 179th Meeting of the Acoustical Society of America, Dec 2020, Acoustics Virtually Everywhere, France. ⟨hal-03430599⟩
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