Investigation On The Fast Prediction Method Of Underwater Sound Radiation From Elastic Cylindrical Shells With Finite Length

The elastic cylindrical shell is a typical structure of underwater vehicles, and the fast prediction of underwater sound radiation from this kind of structures is very important in engineering. Based on BEM, the system software for underwater sound radiation from elastic structures has been developed in this paper by using Fortran and Visual C++ jointly. The investigation on the fast-prediction method of underwater sound radiation from elastic cylindrical shell-structures has been done by use of this system software.To realize the fast prediction of underwater sound radiation, two crucial technologies, the pre-computation of the coefficient matrix and its interpolation in frequency domain, have been adopted in this paper. Emulation result shows that the use of these two technologies has raised the speed of the prediction of sound radiation greatly. However, considering the application of these methods in engineering, two approximate methods of prediction of sound radiation from elastic structures have been put forward in this paper, in which the amplitude of the normal velocity and the mean square amplitude of the normal velocity on structure's surface have been used respectively, instead the use of the complex values of the normal velocity on structure's surface.The radiated sound power is an important acoustic item for a submerged elastic structure. To research the method of the fast prediction of sound radiation power, in this paper, the emulation experiments of the fast prediction of sound radiation power from various models have been carried out by use the approximate methods mentioned earlier. The results show that the predicted curve is well similar to the theoretical one in the analysis frequency band. But the calculating time is far less by the approximate method than that by normal BEM.The analogy of the vibration and sound radiation from a pulse sphere source , from a swing sphere source and from a submerged structure has been analyzed in this paper. The analyzed result has well explained the differences of radiated sound power curves obtained by the fast predicted method and by normal BEM respectively. Based on these results, the method that the prediction of radiated sound power has been revised in different frequency bands has been put forward. The emulation result shows that the predicted precision of radiated sound power has been raised in some degree by use of this kind of revised method. However, how to select the best revised factor need researching further.The research work in this paper may be a reference to the fast prediction of the sound radiation from the submerged complex elastic shell-structures.