Parameters estimation of the underwater vehicle model based on the calculation of an unsteady signal scattering characteristics

The results of a numerical solution of the problem of scattering an unsteady sound signal on a finite isotropic cylindrical shell located in an infinite liquid medium are obtained. The shell has hemispherical tips and is considered as a model of the hull of an uninhabited underwater vehicle. Incident pulses from a rectangular envelope and frequency-modulated pulse signals at different angles of the model location are considered. The solution of the problem involves decomposing the Fourier images of the pressures and potentials of the shell material into series according to the eigenfunctions of the Helmholtz equation for a given surface shape. Using the spectrum of the scattered signal in the frequency band, the shape and duration of the scattered pulse are found. To calculate the latter, the values of the angular scattering characteristics of stationary sound were used, obtained based on the numerical solution of the boundary integral equation at nodal points on the shell surface. The temporal and spectral scattering characteristics for different shell thicknesses and materials for the reverse, specular, and shadow directions are calculated and analyzed.