The Fast Prediction Of Sound Radiation From Submerged Elastic Shell-Structures

This paper focuses on fast prediction method of sound radiation from the submerged finite elastic shell. The model adopted is a submerged cylindrical shell with hemispherical caps on the ends. The Boundary Element Method is used for fast predicting sound radiation from the submerged finite elastic shell, in which the normal velocity on the surface of source is known presumably. In order to predict the underwater acoustic radiation rapidly, three methods have been researched:1. Pre-computation of the coefficient matrix. After the cylindrical shell has been meshed properly, the coefficient matrix associated with the sound pressure on the surface of shell and sound pressure in near field at each frequency can be calculated by BEM respectively. Then, the coefficient matrix has been saved in the database.2. Sound Radiation prediction. In the process of fast prediction, sound pressure on the surface of shell is numerically calculated by BEM based on the normal velocity on the surface of the shell and the coefficient matrix in the database. And then, the radiated sound power, source level, sound pressure in near field and the directivity of sound pressure in far field can be obtained.3. Frequency Interpolation. It is almost impossible to calculate the coefficient matrix at each frequency for broadband signal. However, the coefficient matrix of some main frequencies can be calculated and saved in the database before the prediction of radiated sound field. Then, the coefficient matrix of other frequencies can be obtained by frequency interpolation. Finally, BEM is used to predict the sound radiation from the cylindrical shell by means of the coefficient matrix and the normal velocity on the surface of shell, which will greatly improve the calculating speed.Based on the fast prediction method, the factors of affecting the errors of sound radiation prediction have been studied, including the density of vibrating measuring points on the surface of shell, sound pressure on the shell surface, the phase of the normal velocity. The research work in this paper is valuable for the fast prediction of the sound radiation from the submerged complex elastic shell-structures.