一种减小尺寸的声彩虹捕获效应结构*

该文提出了一种减小尺寸的彩虹捕获效应结构,在铁板上刻上深度相同的空气凹槽阵列并加入周期性缝板单元,通过调节缝宽得到不同的等效折射率。该文对1000 Hz～2000 Hz的声波进行仿真实验,仿真结果表明不同频率的声波被局域在不同的位置,即实现了彩虹捕获效应。由于局域处声波群速度很小,局域处声场能量得到很大的提升。相对于传统的深度渐变的空气凹槽结构,我们的结构尺寸更小,可调性更强,更容易实现对低频声波的捕获效应。该结构具有能量加强和声波空间分离的效应,相信在声吸收、声波识别等领域有着潜在的应用前景。

A size-reduced acoustic rainbow trapping structure

In this paper, we propose a size-reduced acoustic rainbow trapping structure by inserting several layers of crack plates in an array of air grooves. The grooves are decorated in the iron plate with equal depth. By changing the gap between the two plates, different effective refractive indices can be obtained. The performances of the structure are validated by simulations from 1000Hz to 2000Hz. The acoustic waves with different frequencies stop propagating ahead and trapped at different positions of the air groove grating which is called rainbow trapping. The intensity of acoustic field is effectively enhanced near the propagation stop position due to the slow group velocity. Compared with the traditional graded air groove grating, this structure has a reduced size and is more controllable. In addition, it is more possible to realize the wave trapping in low frequency. We believe that such system with the capability of energy concentration and wave spatial arrangement by frequencies has potential applications in acoustic wave absorption and sensing.