Guo Jingwen, Fang Yi, Jiang Ziyan, Zhang Xin
Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Hong Kong, China.
J Acoust Soc Am. 2021 Jan;149(1):70. doi: 10.1121/10.0002990.
The noise attenuation properties of an acoustic liner consisting of Helmholtz resonators with extended necks (HRENs) are investigated. An optimal liner constructed by 16 inhomogeneous HRENs is designed to be effective in sound absorption in a prescribed frequency range from 700 to 1000 Hz. Its quasi-perfect absorption capability (average absorption coefficient above 0.9) is validated by measurements and simulations. The resonance frequencies of the individual resonators in the designed liner are just located within the effective absorption bandwidth, indicating the overlapping phenomenon of absorption peaks. In addition, the liner maintains a thin thickness, about 1/25th with respect to the longest operating wavelengths. To assess the acoustic performance of the designed liner in the presence of mean flow, experimental investigations are performed in a flow tube. Results show a near flat transmission loss is attained in the target frequency range by the designed liner. Additionally, the impedance of the uniform HREN-based liner is extracted at flow condition. In all, the inhomogeneous HREN-based liner is featured by the thin thickness and the excellent wide-band noise attenuation property. These features make the designed liner an promising solution for noise attenuation in both static and flow conditions.
研究了一种由带延长颈部的亥姆霍兹共振器（HREN）组成的声学衬里的噪声衰减特性。设计了一种由16个非均匀HREN构成的最优衬里，使其在700至1000赫兹的规定频率范围内具有有效的吸声效果。通过测量和模拟验证了其准完美吸收能力（平均吸收系数高于0.9）。设计衬里中各个共振器的共振频率恰好位于有效吸收带宽内，表明存在吸收峰的重叠现象。此外，该衬里保持较薄的厚度，相对于最长工作波长约为1/25。为了评估设计衬里在有平均流情况下的声学性能，在流管中进行了实验研究。结果表明，设计衬里在目标频率范围内实现了近乎平坦的传输损耗。此外，还在流动条件下提取了基于均匀HREN的衬里的阻抗。总之，基于非均匀HREN的衬里具有厚度薄和优异的宽带噪声衰减特性。这些特性使设计的衬里成为在静态和流动条件下进行噪声衰减的有前途的解决方案。
