Research On Sound Propagation Direction Control Of Underwater Acoustic Metasurfaces

Acoustic metasurface is a low-dimensional acoustic metamaterial.This article introduces the current domestic and foreign research status of acoustic metamaterials and acoustic metasurfaces,deeply studies a series of problems in them,and constructs an adjustable underwater acoustic wave.Acoustic metasurfaces with refraction angles and a metasurface structure that can realize the asymmetric transmission of underwater acoustic waves have carried out research on the refraction characteristics of acoustic metasurfaces.According to the generalized Snell’s law,an acoustic metasurface with periodic changes in uniform medium is constructed,which realizes wide-band sound wave control with a bandwidth of 7.5k Hz～50k Hz,and the correctness of this model is verified by the angle spectrum method and COMSOL simulation.Then,by analyzing the sound wave refraction under the condition of oblique incidence,it is found that the sound wave incident on the acoustic metasurface will produce multi-order refracted waves,and will achieve a limited angle of negative refraction outside the critical angle,and then use the acoustic metasurface to achieve a full angle The phenomenon of negative refraction also reveals the influence of the angle of incidence of sound waves,density and speed of sound,and the number of elements in the period on the phenomenon of negative refraction.Based on the modified generalized Snell’s law of diffraction order,an acoustic metasurface model that can realize asymmetric sound transmission is established.When the sound wave is transmitted in the forward direction,it can be conducted normally,but when the sound wave is transmitted in the reverse direction,the sound wave is suppressed.The feasibility of the asymmetric propagation of the acoustic wave in the model was simulated through factors such as acoustic wave frequency and acoustic wave amplitude,which verified the correctness of the model.Finally,a reasonable study on the parameter change of asymmetric acoustic wave transmission is carried out.By changing the relevant parameters such as the period width,the number of units in the period,and the unit impedance,the parameter analysis of the acoustic wave asymmetric transmission effect is carried out,and the asymmetry of the high acoustic rectification coefficient is realized.transmission.Finally,two kinds of metasurface samples were prepared,and the abnormal refraction characteristics of the samples under the multi-angle incidence of sound waves and the asymmetric acoustic wave transmission characteristics of the samples under the incident and reverse incidence of sound waves were verified in the pool.Application provides theoretical and experimental basis.