Study on the Acoustic Scattering Characteristics of the Parametric Array in the Wake Field of Underwater Cylindrical Structures

The wake generated by the underwater structure can evolve into a wake vortex with a special flow structure, resulting in a change in the speed of sound distribution, which has an important impact on the propagation of parametric array in the ocean and causes fluctuations in the sound field. The difference-frequency sound wave generated by the parametric array is the core of the parametric array technology. The study of the difference-frequency sound field distribution characteristics is the basis for the development of the parametric array technology and the theory of the interaction of sound waves. The frequency domain algorithm is used to calculate and analyze the nonlinear acoustic scattering characteristics of the underwater vortex field and explore the nonlinear acoustic scattering characteristics of the wake field of a cylindrical structure under the conditions of different moments and Mach number. The results show that the spatial directivity of the nonlinear acoustic scattering field of the wake vortex will cause the directivity of the parametric acoustic field to shift. The difference-frequency wave becomes concave and convex on the opposite sides of the parabolic axis and the wave energy is focused and scattered. The focus will cause the amplitude of the wave to increase and decrease accordingly. The main lobe offset will increase as the flow velocity increases.