耦合声波导的多模谐振机理及其应用研究

Sound wave is an important method for information transmission between different fluidic materials, especially between sea and air. However, there is severe impedance mismatching between water and air. The traditional impedance matching model just generates sound transmission at a single and narrowband frequency and weaken efficiency and safety of information transmission between sea and air. In the proposal, we provide a multimode generation method in coupling acoustic waveguides, using coupling effects of the multimode realizes acoustic impedance matching at many resonant frequencies and sound transmission regulation between different fluidic materials. Theoretically, the proposal will reveal mechanisms of multimode resonances and coupling law in multimode. Then, the resonances at ultra-low frequencies excited by sub-wavelength acoustic structure with a composite acoustic cavity will be investigated. In final, effects of liquid level and structure parameters of the coupling waveguide on the sound transmission spectra will be studied to give theoretical and technical supports for sound transmission regulation between sea and air. In experiments, the measurements will optimize the theoretical model and fabricated acoustic waveguide. Meanwhile, applications of the information transmission between sea-air and noise at low frequencies will be investigated. In summary, the proposal enriches the theory of impedance matching in complex multilayer media, which is important for impedance matching at multi-resonant points and sound transmission regulation between different fluidic media.

声波在异质流体介质特别是水-空气间传播为海-空一体化信息传输提供重要手段。但是，水-空气间存在严重的声阻抗失配，传统的阻抗匹配方式仅能传输单频、窄带声波，这影响了声信息在海-空之间的传输效率和安全。本项目基于申请人前期的声结构多模谐振研究，利用耦合声波导激发多模谐振态实现异质流体介质间的多频率点阻抗匹配和声波传输调控。理论上：项目揭示耦合声波导的多模谐振激发机制以及模式间耦合规律；同时，项目提出子波长微腔体结构，揭示子波长耦合声波导的低频谐振模式激发机制；此外，项目通过研究耦合声波导液面和结构参数对声波透射谱的影响规律，为海-空之间声波传输调控提供理论、技术支持。实验上：项目通过测量修正和优化理论模型和制备的耦合声波导，并探索耦合声波导在海-空之间信息传输和低频噪声抑制的应用。本项目的研究将丰富复杂介质声阻抗匹配理论，对异质流体介质之间的多点频率阻抗匹配和声波传输调控具有重要意义。

跨介质海洋声探测是海空声信息一体化的理论基石，其不断认知与发展是推动声学探测变革的核心动力。随着海洋探测向“海空一体化”和“网络化”方向不断发展，海洋声探测已经从传统面向 “海洋系统” 向涵盖海洋-低空-航（飞）行器的一体化“综合系统”演化。其涉及的海空跨介质声探测的核心内容是亟需突破的 “瓶颈”，受到声学研究的高度重视。申请人瞄准海空跨介质海洋声探测发展的前瞻技术，坚持基础理论与应用相结合，深刻剖析复杂介质声传播理论，针对海空跨介质海洋声探测中的复杂声场调控理论模型、跨介质声阻抗匹配及透射声场优化、高灵敏度声信号检测三个关键科学问题开展了深入研究，取得了创新性成果。①建立了耦合声波导声传播理论模型，揭示了耦合声波导的多模谐振机理，明确了结构参数对声波透射和声波传输的抑制规律。②提出了耦合声波导的海空跨介质间声波透射频谱优化方法，揭示了波导管几何结构对多点频谱的优化规律，实现了耦合波导的可调谐海空跨介质声透射。③建立了多结构耦合、非局域谐振的子波长耦合声结构设计理论，提出了声振耦合、流固耦合、柔性体-刚性体耦合的多场和多结构声波调控模型。④建立了声超构材料制备平台，制备了海空跨介质声调控结构，建立了跨介质声场测试系统，实验测试了可调谐海空跨介质声透射性能。⑤在本项目资助下培养研究生7名，其中博士研究生3名；发表标注项目资助信息的SCI学术论文13篇，课题组成员参加国际、国内会议12人次，授权发明专利9件。