Research On Forecasting Sound Scattering Field From Elastic Targets In Deep Water By Directional Point Source Equivalence

At present,the problem of sound scattering is usually analyzed in the free field.Considering the coupling effect of the elastic target structure with the complex ocean environment and boundary,it is difficult to provide a rigorous solution for sound scattering,and a large degree of simplification is generally required.This paper studies the sound scattering of elastic target structures under deep sea conditions.In this paper,by equating the sound scattering field of a complex elastic target to a directional point sound source sound field,a rapid prediction method of target sound scattering in a deep sea channel is proposed.Under deep sea conditions,ignoring the influence of the surface impedance characteristics of the elastic target from the sea surface,through the finite element simulation of sound scattering in a free field,the sound scattering field is equivalent to the radiation field of a directional point sound source,and then the point source is placed in the ocean environment,and the ray acoustic method is used to calculate the sound scattering field distribution in the ocean environment.The core of the theory of directional point source equivalence is to realize directional point source equivalence on the scattered sound field in the far field.Based on a number of different models and many factors considered such as the equivalent position,the position of decomposition surface,boundary effect,sound velocity gradient,the applicability of the equivalent method of directional point source is obtained by analysis.The simulation results show that the equivalent position of the directional point source must be selected in the far field;the choice of decomposition surface position has little effect on the method;the waveguide boundaries have a great influence on the scattered sound field,and when the boundary is far enough from the targets,the sound field calculation result is more accurate;comparing the sound scattering field with different sound velocity gradient models,the results show that the sound velocity gradient has little effect on the method;compared with the finite element method(FEM),the calculation ability and speed of this method have obvious advantages.Therefore,it can be explained that the directional point source equivalence method has good accuracy,stability and efficiency.Furthermore,the directional point source equivalence is used to calculate the sound scattering field of the single-shell submarine model,the double-hull submarine model,and the submarine model with a cover layer in the deep-sea waveguide.The spatial distribution characteristics of the sound scattering field of the three submarine models under different incident directions and different diving depths are studied.At last,the validity of numerical calculation and the law of the target intensity.