结构在浅水中的振动和声辐射特性研究

建立了浅水域声学边界元方程和相应的有限元／边界元流固耦合振动方程，探讨了水深对结构振动固有频率、振动响应和声辐射的影响。研究结果表明：水深变化对结构固有频率有影响，随着水深减小，结构固有频率降低，特别是当水深与结构浸深接近时，各阶固有频率大大降低，且振型顺序也可能发生变化；水深变化对结构振动响应和声辐射均有影响，其中对声辐射特性的影响较为复杂，即使水深超过结构浸深的10倍，水深变化也会影响到结构的声辐射功率级。

A Vibro-Acoustic Study on Structures in Shallow Water

In this paper, the BEM for the acoustics analysis in shallow water and the coupled FEM/BEM fluid-structure interaction equation are established, and then the impact of water depth on the natural frequencies, vibration responses and acoustic radiation of underwater structures are discussed. The results of this study show that the shallow water has an influence on the natural frequencies of structures in the way that the natural frequencies decrease as the water depth decreases. It is also noted that the natural frequencies of structures decrease a lot and even the sequence of mode shapes changes if the water depth is very close to the drafts of structures. Besides, the authors find that the water depth also has an influence on vibration responses and the acoustic radiation of structures, but its impacts on the acoustic radiation are much more seriouse in a remarkably complex way than on the vibration responses. For example, the water depth can still have an influence on the sound power even if the water depth is over ten times the draft of the structure, while the mean square velocity of the structure almost never changes if the water depth is over four times the draft of the structure.