Boulvert Jean, Gabard Gwénaël, Romero-García Vicente, Groby Jean-Philippe
Laboratoire d'Acoustique de l'Université du Mans (LAUM), UMR 6613, Institut d'Acoustique - Graduate School (IA-GS), CNRS, Le Mans Université, Le Mans, France.
Sci Rep. 2022 Jun 15;12(1):10013. doi: 10.1038/s41598-022-13944-1.
This work deals with wave absorption in reciprocal asymmetric scattering problem by addressing the acoustic problem of compact absorbers for perfect unidirectional absorption, flush mounted to the walls of wide ducts. These absorbers are composed of several side-by-side resonators that are usually of different geometry and thus detuned to yield an asymmetric acoustic response. A simple lumped-element model analysis is performed to link the dependence of the optimal resonators surface impedance, resonance frequency, and losses to the duct cross-sectional area and resonator spacing. This analysis unifies those of several specific configurations into a unique problem. In addition, the impact of the potential evanescent coupling between the resonators, which is usually neglected, is carefully studied. This coupling can have a strong impact especially on the behavior of compact absorbers lining wide ducts. To reduce the evanescent coupling, the resonators should be relatively small and therefore their resonances should be damped, and not arranged by order of increasing or decreasing resonant frequency. Finally, such an absorber is designed and optimized for perfect unidirectional absorption to prove the relevance of the analysis. The absorber is 30 cm long and 5 cm thick and covers a single side of a 14.8 × 15 cm rectangular duct. A mean absorption coefficient of 99% is obtained experimentally between 700 and 800 Hz.
这项工作通过解决紧密吸收器的声学问题来处理互易非对称散射问题中的波吸收，以实现完美的单向吸收，该吸收器齐平安装在宽管道壁上。这些吸收器由几个并排的谐振器组成，这些谐振器通常具有不同的几何形状，因此失谐以产生非对称的声学响应。进行了一个简单的集总元件模型分析，以将最佳谐振器表面阻抗、共振频率和损耗的依赖性与管道横截面积和谐振器间距联系起来。该分析将几种特定配置的分析统一为一个独特的问题。此外，还仔细研究了谐振器之间通常被忽略的潜在消逝耦合的影响。这种耦合可能会产生强烈影响，尤其是对宽管道内衬紧密吸收器的行为。为了减少消逝耦合，谐振器应该相对较小，因此它们的共振应该被阻尼，并且不应按共振频率增加或减少的顺序排列。最后，设计并优化了这样一种吸收器以实现完美的单向吸收，以证明分析的相关性。该吸收器长30厘米，厚5厘米，覆盖了一个14.8×15厘米矩形管道的一侧。在700至800赫兹之间通过实验获得了99%的平均吸收系数。
