Bandgap characteristics of a duct embedded with multiple membrane-cavity resonators in the presence of mean flow
Bandgap characteristics of a duct embedded with multiple membrane-cavity resonators in the presence of mean flow
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DOI：
10.1016/j.ijmecsci.2019.105330
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发表时间：
2020-03-01
影响因子：
7.3
通讯作者：
Du, Jingtao
中科院分区：
文献类型：
--
作者：
Liu, Yang;Du, Jingtao
周期性结构的带隙特性可以通过反射和透射系数由有效材料性质来研究。在本文中，第一次，相应的有效特性，如质量密度，相对阻抗和折射率的管道嵌入在其侧壁的膜腔谐振器。在膜或腔共振频率附近，有效密度随负值急剧变化，这意味着其加速度与动压载荷具有相反的相位，在该相位内几乎可以获得全声压反射。此外，流动的存在将导致相对阻抗和折射率的幅度显著减小，特别是对于谐振峰。最后研究了平均流量对周期谐振单元带隙特性的影响。在布拉格反射和局部共振带隙中可以观察到显著的减小和轻微的偏移，并且它们的色散曲线（每个单元的相位变化）在这些带隙内不能达到零或+/-π。这意味着管道中的流动类似于阻尼效应，导致色散分支不能覆盖整个布里渊区。
Bandgap characteristics of periodic structures can be investigated by the effective material properties via reflection and transmission coefficients. In this paper, for the first time, corresponding effective properties such as mass density, relative impendence and refractive index are presented for a duct embedded with membrane-cavity resonators in its sidewalls. Around the membrane or cavity resonant frequencies, the effective density varies drastically with the negative values, implying that its acceleration has opposite phase with the dynamic pressure load, within which almost a total sound pressure reflection can be obtained. Moreover, the presence of flow will cause a significant decrease in both the amplitude of relative impedance and refractive index, especially for the resonant peaks. Mean flow effect on bandgap characteristics of periodic resonant cells is conducted in the last part. Significant decrease and slight shift can be observed in the Bragg reflection and locally resonant bandgaps, and their dispersion curve (phase change per cell) cannot reach zero or +/-pi within these bandgaps. It implies that the presence of flow in duct is similar to the damping effect which leads to the dispersion branch that cannot cover the entire Brillouin zone.