Numerical Analyzing of the Cavity Scatterer Effect on the Acoustic Performance of Echo Reducing Layers with Doubly Periodic Distribution Using FEM

The echo reduction of an underwater vessel is one of the major concerns of its concealing problem. Recently, using scatterers in the doubly periodic distribution has attracted enormous interest. This is because of their relatively good performance and the ability to tune in the effective frequency range. In this study, a model of an acoustic echo reducing coating with internal scatterer cavities is considered. Subsequently, the major parameters that affected the acoustical performance of the layer, such as the size, the number and the location of cavities along with the thickness, for two types of spherical and cylindrical cavity geometries, were analyzed and presented. The results showed that in the layer, the larger the cavity size, the greater the echo reduction effect. Regarding the lattice constants, considering the smaller one, decays the echo reduction. However, will increase transmission loss. Also, the location of the cavity, if close to the wave entry plane, demonstrates a better echo reduction effect.