水下亚波长广角声单向传输结构设计与优化

Design and optimization of a sub-wavelength unidirectional transmission structure for underwater acoustic waves with multiple incident directions

利用传递矩阵法,基于流固超晶格的单元传递矩阵,计算并分析了无限周期流固超晶格的能带结构以及有限周期级联超晶格的透射谱。在此基础上,耦合一维周期性矩形声栅与级联超晶格,构造了水下亚波长广角声单向传输结构,揭示了其广角声单向传输机制。有限元仿真结果表明,该结构能够实现约20°广角入射声波的单向传输效应,同时还具有宽频带、高整流比等特性。通过优化声栅单元的方位角,有效地提高了结构的正向导通率。本文结果突破了基于声子晶体的声单向传输设计中面临的“波长-尺寸”限制,有助于水下声整流器件朝着小型化和集成化方向发展。

Using the transfer matrix method,the band structure of the infinite solid-fluid superlattice and the transmission spectrum of the finite cascaded superlattice are calculated and analyzed based on the transfer matrix of the unit cell of superlattice.On this basis,the underwater sub-wavelength wide-angle acoustic unidirectional transmission structure is constructed by coupling 1D periodic rectangular acoustic gratings with the cascaded superlattice,and the mechanism of wide-angle unidirectional transmission is revealed.The finite element simulation results show that the structure can realize the unidirectional transmission effect for incident acoustic waves of about 20 degrees,and has the characteristics of broadband and high rectification ratio.Finally,by rotating the unit cell of acoustic gratings,the forward conductivity of the structure is effectively improved.This research breaks through the limitation of“wavelength-size”in the design of unidirectional acoustic transmission based on phononic crystals,and is helpful for the development of underwater acoustic rectifiers towards miniaturization and integration.