Low-frequency sound attenuation by coiled-up meta-liner with nonuniform cross sections under grazing flow

We report a kind of coiled-up meta-liners with nonuniform cross sections (CMNC), which can efficiently attenuate low-frequency sound waves under grazing flow with a deep subwavelength thickness (e.g., ∼λ/17 at 500 Hz). At a grazing flow Mach number of 0.26, the average transmission loss of the meta-...

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Bibliographic Details
Published in:Journal of applied physics 2024-05, Vol.135 (20)
Main Authors: Wang, Hao, Zeng, Xiangyang, Ren, Shuwei, Xue, Dongwen, Li, Zhuohan, Wang, Haitao, Lei, Ye
Format: Article
Language:English
Subjects:
Acoustic attenuation
Acoustic liners
Bypass ratio
Cross-sections
Energy dissipation
Grazing flow
LF noise
Mach number
Numerical methods
Sound attenuation
Sound waves
Transmission loss
Turbofan engines
Vortex shedding
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Summary:We report a kind of coiled-up meta-liners with nonuniform cross sections (CMNC), which can efficiently attenuate low-frequency sound waves under grazing flow with a deep subwavelength thickness (e.g., ∼λ/17 at 500 Hz). At a grazing flow Mach number of 0.26, the average transmission loss of the meta-liner is 12.6 dB at 500–1000 Hz, which is twice as much as that of a double-degree-of-freedom acoustic liner of the same size. Physically, the nonuniform cross-sectional distribution and significant cross-sectional area ratio enhances vortex shedding, thus resulting in severe acoustic energy dissipation. The excellent low-frequency acoustic attenuation performance of CMNC is investigated thoroughly with experimental, theoretical, and numerical methods. This work provides an avenue for low-frequency noise reduction in grazing flow scenarios (e.g., in a high bypass ratio turbofan engine).
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0203941