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Effect of Back Cavity Configuration on Performance of Elastic Panel Acoustic Liner with Grazing Flow
Journal of Sound and Vibration ( IF 4.7 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.jsv.2020.115847
Garret C.Y. Lam , Randolph C.K. Leung , Harris K.H. Fan , Yves Aurégan

Abstract This paper reports a comprehensive numerical study of noise mitigation performance of elastic panel liner comprising an elastic panel and a cavity beneath exposed to low Mach number grazing flow. A time-domain direct aeroacoustic simulation (DAS) seamlessly coupled with panel dynamics is adopted for its least assumptions taken on duct flow unsteadiness and acoustical behaviors so that both linear and nonlinear aeroacoustic-structural interactions of the problem can be fully explored. The numerical method is well validated with theoretical and experimental works on a liner with thick cavity reported in literature. The noise mitigation of liner with various combinations of cavity depth, panel length and cavity shape, are explored and the present numerical results show that back cavity configuration plays an important role in the liner problem. A decomposition method is applied to DAS acoustic solutions for uncovering the role of aeroacoustically induced panel vibration. The nonlinear effect due to aeroacoustic-structural interaction is found to be of secondary importance. Extensive cross spectral analyses between duct aeroacoustics and panel vibration reveal that the overall liner performance is largely determined by the liner elastic panel whose aeroacoustic and vibration responses are greatly modified by the variations of back cavity acoustics of the back cavity with different shapes. Based on these understandings a new configuration with acoustic absorption materials placed on a cavity wall is proposed. Detailed analysis of its numerical results shows that the introduction of acoustic absorption effectively relieves the cavity acoustics and modifies the panel responses in such a way that an enhanced liner mitigation performance over a broadband can be achieved.

中文翻译:

背腔结构对带掠流弹性板声学衬垫性能的影响

摘要 本文报道了由弹性板和暴露于低马赫数掠流下的空腔组成的弹性板衬垫的降噪性能的综合数值研究。采用与面板动力学无缝耦合的时域直接气动声学模拟 (DAS),因为它对管道流动不稳定和声学行为的假设最少,因此可以充分探索问题的线性和非线性气动声学-结构相互作用。该数值方法在文献中报道的厚腔衬管上的理论和实验工作得到了很好的验证。腔深、面板长度和腔体形状的各种组合的衬垫降噪,进行了探索,目前的数值结果表明,背腔配置在衬垫问题中起着重要作用。将分解方法应用于 DAS 声学解决方案,以揭示气动声学引起的面板振动的作用。发现由于气动声学-结构相互作用引起的非线性效应是次要的。管道气动声学和面板振动之间的广泛交叉谱分析表明,整体衬里性能在很大程度上取决于衬里弹性面板,其气动声学和振动响应因背腔不同形状的背腔声学变化而大大改变。基于这些理解,提出了一种将吸声材料放置在空腔壁上的新配置。
更新日期:2021-02-01
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