水下航行体垂向弯曲振动声辐射特性

The Characteristics of Vertical Bending Vibration and Sound Radiation of Underwater Vehicle

垂向弯曲振动是水下航行体总振动的常见模式,控制弯曲振动是水下航行体设计中重要的一环。考虑声—结构耦合,基于FEM/BEM理论建立航行体弯曲振动声辐射分析的基本方程,计算水下航行体垂向弯曲振动固有频率和振动响应,研究弯曲振动引起的辐射声场特性;并以振动评价基准中的速度限制线作为激励,讨论航行体弯曲振动声辐射。结果表明:航行体垂向弯曲振动会产生较大的辐射噪声,1阶和2阶振动对总振动引起的辐射噪声贡献较大;欲降低低频线谱,须降低振动响应幅值;在结构振动控制设计中,不仅要从结构振动烈度的角度控制弯曲振动响应幅值,还应考虑结构声学性能,从控制弯曲振动引起的声辐射角度出发,补充提出设计指标。

Vertical bending vibration mode is one of the common vibration modes of underwater vehicle structure. To control bending vibration is an important task in design of underwater vehicle. The equations of bending vibration and acoustic radiation of the underwater vehicle were established based on the theroy of FEM/BEM with considering sound-structure coupling effects, the natural frequencies and forced vibration responses were calculated numerically to find out the cheracteristics of sound radiation induced by vertical bending vibration, and the characteristics of sound radiation by the excitation velocity of the value on restriction line in vibration criteria graph were discussed. The results show that vertical bending vibration does bring about significant noise, and the contribution of first and second vibration modes is dominant in sound radiation. For reducing line spectrum the vibration response at low frequencies must be lowered. In design of structure vibration control, additional criteria should be proposed specially for reducing bending vibration induced sound radiation except that for vibration severity.