基于拓扑声子晶体的高指向性声辐射研究

定向声辐射技术可以控制声源的传播方向和声波的覆盖范围，在声学通信、探测与感知等领域意义重大。现有的声学人工结构定向声辐射系统虽然可以克服传统扬声器阵列的系统复杂性问题，但仍存在可实现工作频段极窄、波束宽度过大等局限，难以满足声辐射调控的需求。近期研究表明，拓扑声子晶体中界面声传输模式能有效局域声波并精准匹配波矢量，从而实现针式指向性的波束成形，具有丰富的物理效应和广阔的应用前景。由于拓扑声子晶体中声散射的复杂性，其界面传输模式的激发过程与有效工作频带的关系尚不清楚，辐射声束仰角的调控机理也未澄清。为此，本项目将深入研究拓扑声子晶体中声单向边界态的激发机制，挖掘伴随谷涡旋模式形成的声学参量，以有效调控声辐射系统的工作频带；同时，深入研究不同微结构参数演化对波矢匹配的影响，扩大可选择的横向波矢区间，拓展辐射波束的仰角范围，进而在此基础上构建新原理高指向性声学器件，以更好地满足声学应用的需求。

Directional sound radiation can control the propagation direction and coverage area of sound source, which has great significance in acoustic communications, detections, and sensing. In spite of the superiority over the inherent system complexity problem of traditional loudspeaker array, current sound radiation systems based on acoustic metamaterials are still restricted by the extremely narrow working frequency range and broad beam width. These deficiencies cannot fulfill the application requirements of efficient sound radiation manipulations. Recent studies have shown that the interface acoustic modes in topological phononic crystals can concentrate the sound waves efficiently while match the wave vectors precisely, and thus achieve beam forming with needle-like directivity, in which rich physics and promising applications are prospected. However, due to the complexity of sound scattering processes in the topological phononic crystals, the relationship between the excitation of acoustic interface mode and the working band is not clear. In addition, the mechanism of directivity angle manipulation is not clarified. Thus, this project will study the excitation mechanism of acoustic one-way interface modes, explore the acoustic parameters associated with the formation of valley vortex modes, and extend the operation frequency range of sound radiation system. At the same time, we further study the effects on wave vector matching by the variation of system parameters in different types, enrich the selectable parallel wave vector, and extend the range of directivity angle. On this basis, we will develop novel sound radiation devices with high directivity, which are essential for the acoustic applied technologies.