Study On Mechanism Of Underwater Discrete Anechoic Array

With the continuous development of sonar systems in low-frequency and high-power direction, the submarine hidden has been high demanded in increasingly. Continuous muffler cover layer technology has been difficult to achieve low frequency anechoic problems. In this paper a discrete array muffler structure was been proposed to solve this problem. Acoustic unit of viscoelastic material has been covered on the surface of pressure metal's cavity structure. And then acoustic cell cycle has been arranged to form a series of discrete muffler array.In this paper, the finite element method has been used for underwater arrays of discrete silencer mechanism. In order to research the facilitate the mechanism, acoustic elements are arranged into an infinite cycle of flood medium, ANSYS software was used for finite element mesh which was composed by medium water cycle,structure and side interface. Cycle unit is a hexahedron, included an incident end face, a transmission end face and four sides of the structure generated periodically. And in these four sides, according to Bloch theory, node sound pressure and displacement have cycle relationships. As the existing finite element software can not handle these periodic boundary conditions,so this paper use self finite element simulation analysis of underwater discrete silencer array.Then used the analytical method to emulation analysis underwater elastic sphere, elastic spherical shell and scattering sound field. Deduced the analytical solutions of scattering field and shell covering with spherical viscoelastic material. Understood the scattering characteristics for an acoustic unit to provide a basic about selecting acoustic unit of underwater acoustic array of discrete silencer. Numerical analysised the performance of underwater acoustic muffler array of discrete and compared the effects of different types of acoustic insulation effect unit. For the same kind of acoustic unit, the acoustic unit size and the impact of changes in the viscoelastic layer of material parameters, include the density,Young's modulus, loss factor, thickness, Poisson's ratio, on an array of acoustic performance muffler was discussed.Finally, according to the simulation model silencer array structure, five acoustic processing unit was machined, Cloth were placed in a pressure tank bulkhead. The performance of underwater acoustic silencer discrete array was studied by measuring the presence or absence about sound power radiated of acoustic unit in far field under different pressure conditions. Test data analysis showed that: the finite element method for the study of underwater acoustic performance muffler discrete array is applicable; underwater discrete array structure of the low-frequency noise muffler is effective.