基于辐射噪声线谱削峰的双层加肋圆柱壳结构声学设计

为降低水下航行器辐射噪声线谱，提出了一种弱辐射双层加肋圆柱壳结构. 采用机械阻抗理论分析了环肋圆柱壳模态响应幅值控制机理；引入圆截面内运动假设，利用模态展开法推导了环肋径向机械阻抗表达式；基于阻抗失配、波形转换原理，设计了阻抗加强环肋模型，并利用波动理论分析了其隔振性能；考虑壳间托板的强耦合作用，对托板进行了阻波设计. 将阻抗增强肋骨和复合阻波托板联合应用到双层壳结构声学设计中，数值分析了设计前后双层壳振动与声辐射性能. 结果表明:提出的新型双层加肋圆柱壳能有效实现辐射噪声线谱削峰，振动均方速度、辐射声功率和辐射声压大幅降低，具有显著的减振降噪效果. 

Structural-Acoustic Design of Double Cylindrical Ring Stiffened Shell Based on Line Spectrum Reduction of Radiation Noise

In order to reduce line spectrum of radiation noise from submarine, a type of weak radiation double cylindrical ring stiffened shell was proposed. Mechanical impedance theory was used to analyze mechanism of controlling the modal response amplitude of ring-stiffened cylindrical shell. Radial modal mechanical impedance of the ring was derived by introducing the assumption of inner-motion of cylindrical shell's section. Based on the concepts of impedance mismatch and wave conversion, the model of impedance enhancement rib was built and its isolation performance was analyzed. With the consideration of the brace's strong coupling effect, the brace's wave attenuation was designed. Combining the structures of reinforced impedance rib and wave attenuation brace, the structure-borne sound design of double cylindrical shell was done. Further, the characteristics of vibration and sound radiation were numerical analyzed. The results show that the proposed double cylindrical ring stiffened shell could realize radiation noise line spectrum reduction effectively. The vibration mean square velocity, radiation sound power and sound pressure are depressed greatly. The effect of noise depression and vibration reduction is obvious.