The Research On Vibration And Sound Radiation From Elastic Structures By Equivalent Method

The submarines are often assumed to be point source models when we discuss the problem of its acoustic radiation in the far field. However, it will not be reasonable when the near and far field acoustic radiation from the submarine's surface vibration need to be considered at the same time. Wave superposition method provides another solution for forecasting the radiated noise of the submarine online. This method is based on the idea that the acoustic field of a complex radiator can be reconstructed from the superposition of fields generated by an array of simple sources enclosed within the radiation. In this article, the principle of wave superposition for free field is deduced in detail, and its feasibility and accuracy are also testified through numerical examples. The calculating errors of the acoustic field by this method are researched numerically. We also proofed the phenomenon that the solution of acoustic radiation through method of point source wave superposition and dipole source wave superposition is non-unique. To solve this problem, we developed the mixed source wave superposition method and complex vector wave superposition method. Another kind of wave superposition method has been developed to predict the sound field in half-space, because the traditional wave superposition method is not suitable in such case, and its feasibility and applicability are also been tested by numerical simulation. To verify the wave superposition methods, an experiment has been done in anechoic water tank in Harbin Engineering University. The experimental model is a single-layer cylindrical shell with caps at both ends. The experimental results show the acoustic radiation can be well predicted by wave superposition method.