This paper presents an acoustic metamaterial, coiled-up structure with porous lining (CSPL), which is constructed by adding porous material lining to a coiled-up air channel for the pursuit of broadband and low-frequency sound absorption at subwavelength scales. The porous material is fixed on both sides of the channel wall to enhance the losses of the system, and an air slit is left in the middle of the channel to regulate the impedance matching between the metamaterial and the air. A theoretical model based on double porosity theory and impedance transfer method is established to study the sound absorption performance of the metamaterial, and a finite element (FE) simulation model is constructed to reveal the underlying sound absorption mechanism. To validate these two models, the sound absorption performance of the designed sample is measured in a standing wave tube. The results show that the porous material lining not only enhances the sound energy dissipation, but also reduces the propagation speed of sound wave in the coiled channel, resulting in good low-frequency sound absorption performance of the CSPL. By adjusting the position and length of the porous lining, good sound absorption tunability can be achieved in the considered frequeny range. Moreover, the effect of acoustic properties of the porous material on the sound absorption of the CSPL is revealed and discussed in detail. Finally, several coupled CSPLs are designed to achieve broadband sound absorption in different frequency ranges. This work provides a new approach to design metamaterials for broadband low-frequency sound absorption.

本文提出了一种声学超材料，带多孔衬里的盘绕结构 (CSPL)，它是通过将多孔材料衬里添加到盘绕的空气通道中来构建的，用于在亚波长尺度上实现宽带和低频吸声。多孔材料固定在通道壁的两侧以增强系统的损耗，通道中间留有空气缝隙以调节超材料与空气之间的阻抗匹配。建立了基于双孔隙率理论和阻抗传递方法的理论模型来研究超材料的吸声性能，并构建了有限元 (FE) 仿真模型以揭示潜在的吸声机制。为了验证这两个模型，在驻波管中测量设计样品的吸声性能。结果表明，多孔材料衬里不仅增强了声能耗散，而且降低了声波在盘绕通道中的传播速度，从而使CSPL具有良好的低频吸声性能。通过调整多孔衬里的位置和长度，可以在考虑的频率范围内实现良好的吸声调谐性。此外，还详细揭示并讨论了多孔材料的声学特性对 CSPL 吸声的影响。最后，设计了几个耦合的 CSPL 以实现不同频率范围内的宽带吸声。这项工作为设计用于宽带低频吸声的超材料提供了一种新方法。