| Popis: |
In order to study the acoustic scattering of underwater targets, the conversion factor of plane wave and spherical wave of point sound source was calculated on the basis of the analytical solution of the classical Rayleigh normal series, combined with the expression of Green’s function in the spherical coordinate system. Based on the scattered sound field of the elastic spherical shell under the incidence of plane wave, the scattered sound field of the elastic spherical shell under the incidence of point sound source was solved, and finite element verification was carried out. On this basis, the target strength of typical spherical targets were calculated and analyzed. From the perspective of target strength, the distance from the center of the sphere and the point sound source was quantified, and the condition that the spherical wave was approximately equivalent to the plane wave was proposed. The results show that the peak value of the target strength curve of the sphere will shift relative to the incidence of plane wave when the point sound source is near the sphere. In addition, the spherical wave can be approximated to the plane wave incidence with the dimensionless frequency ka < 50, and the distance between the point sound source and the spherical center is related to the radius and thickness of the spherical shell. The results can provide a theoretical reference for the detection, identification, and underwater acoustic measurement experiments of underwater targets. |
