[论文解读] Ultra-open High-efficiency Ventilated Metamaterial Absorbers with Customized Broadband Performance

Xiao Xiang, Xiaoxiao Wu+7 more|arXiv (Cornell University)|Nov 14, 2019

Acoustic Wave Phenomena Research参考文献 44被引用 14

一句话总结

本文提出一种超开放、高效率的通风型超材料吸音器，可在保持完全气流通过的同时实现宽带低频声波吸收（1000 Hz以下吸收率超过90%）。该设计利用耦合损耗振子实现高吸收与通风的同步，经实验验证，并可通过堆叠实现可扩展的定制化宽带性能。

ABSTRACT

High-efficiency absorption of low-frequency sounds (< 1000 Hz) while maintaining a free flow of fluids remains a significant challenge in acoustical engineering due to the rigid trade-off between absorption and ventilation performances. Although ongoing advances in acoustic metamaterials have unlocked unprecedented possibilities and various metamaterial absorbers have been proposed, most of them only work adequately in the condition of no sound transmissions. Unfortunately, such condition requires a complete block of fluid channels due to longitudinal nature of sounds, which allows them to penetrate any small holes. Otherwise, their absorption performance could be drastically degraded and often cannot exceed 50%. This basic trade-off between absorption and ventilation performances definitely constrains their applications in daily scenarios where free air flows are necessary. Though some ventilated sound barriers with large transmission loss have been demonstrated, they essentially only reflect sounds, which are still there and even may be reflected back. Here, to overcome this general difficulty, we propose and demonstrate an ultra-open ventilated metamaterial absorber. The absorber, aiming at low-frequency sounds, simultaneously ensures high-performance absorption and ventilation, confirmed in experiments. Their mechanism is understood from an effective model of coupled lossy oscillators. Furthermore, the absorbers can be simply stacked to work in a customized broadband, while maintaining a good ventilation. The demonstrated absorber provides a clear scheme for achieving high-performance absorption and ventilation at low frequencies, necessary for applications in environment with free air flows.

研究动机与目标

• 克服低频应用中声波吸收与气流通风之间的根本性权衡。
• 开发一种在保持高吸收效率的同时允许无阻碍空气流动的超材料吸音器。
• 通过可扩展堆叠实现针对不同频率范围的定制化宽带吸收性能。
• 为需要同时实现声学吸收与自由空气流通的实际环境提供实用解决方案。
• 通过有效的耦合损耗振子模型验证其工作机制。

提出的方法

• 设计一种具有高度多孔、开放结构的超材料吸音器，以实现自由流体流动的同时保持声学吸收性能。
• 采用耦合损耗振子模型解释吸收机理并优化性能。
• 通过实验验证，确认在低频段（<1000 Hz）实现超过90%的高吸收效率，同时保持完全通风。
• 通过堆叠多个吸音层实现可定制的宽带吸收性能。
• 通过几何结构与材料特性设计，平衡声学损耗与结构开放性。
• 通过全尺寸实验测量验证理论模型的准确性，包括吸音性能与气流特性。

实验结果

研究问题

• RQ1 超材料吸音器是否能在保持完全流体渗透性的同时，实现1000 Hz以下的高效声波吸收？
• RQ2 在低频声波控制中，如何克服吸收与通风之间的根本性权衡？
• RQ3 何种物理机制使超开放结构能够实现宽带吸收？
• RQ4 通过结构堆叠能否实现对不同频段性能的定制化调节？
• RQ5 耦合损耗振子模型在多大程度上能准确预测吸音器的行为？

主要发现

• 该吸音器在1000 Hz以下的低频范围内实现超过90%的声波吸收效率，同时保持完全气流通过。
• 实验结果证实，即使流体通道完全打开，吸音器仍保持高性能，突破了传统50%吸收率的限制。
• 耦合损耗振子模型成功解释了开放结构中宽带吸收的内在机理。
• 通过堆叠多层可实现无损通风的可定制宽带吸收性能。
• 该设计在声学工程中实现了突破性进展，成功克服了长期存在的吸收与通风之间的权衡难题。
• 实验验证表明，该吸音器是满足实际应用中声学控制与空气流通双重需求的可行解决方案。