Simulated and Experimental Research on Highly Efficient Sound Absorption of Low-Frequency Broadband Acoustic Metamaterial Based on Coiled-Up Space

Acoustic metamaterials are broadly employed in vibration and noise reduction fields for large defense industrial equipment such as engines and compressors thanks to their excellent subwavelength characteristics and extraordinary acoustic performance. However, the low-frequency broadband sound absorption remains a thorny challenge in the scientific and engineering communities. This paper focuses on the low-frequency broadband acoustic metamaterial composed of eight spiral absorbers coupled in two rows, researching its thermoviscous dissipation and sound absorption mechanism, and further analyzing its sound absorption characteristics. In the frequency range of 510–990 Hz, the average sound absorption coefficient of acoustic metamaterial with sound absorption area ratio of 2.72% reaches 0.80, and the cross-sectional height is only 34 mm, which achieves the tradeoffs between structural thickness, frequency bandwidth and sound absorption performance. Furthermore, continuous and highly efficient broadband sound absorption within the target frequency band in practical applications can be achieved by optimizing adjustable parameters. In addition, finite element simulations are verified by experiments, which presents good agreement. Compared with traditional sound absorbing structure, the low-frequency broadband acoustic metamaterial proposed in this paper owns the characteristics of small size and easy processing, which has broad application prospects in the field of low-frequency noise control engineering.