敷设气囊的充水圆柱壳的声辐射

为降低充水圆柱壳受内部点声源激励时的水下辐射噪声，在其外壳上敷设气囊，形成气囊圆柱壳。为指导气囊圆柱壳的设计，将充水裸圆柱壳和充水气囊圆柱壳分别简化为单、双层无限长隔板。比较隔板、气体与水的波阻抗，分析了气体声速与层厚对双层无限长隔板在平面声波入射时低频声辐射的影响机理。分析表明，声速小的气体和适当的气层厚度可以降低双层障板的辐射噪声。采用声无限元法计算了气囊圆柱壳的水下声辐射，结论与对隔板的机理分析吻合。优化设计出的充水CO2气囊圆柱壳的水下辐射声功率与远场辐射声压明显低于充水裸圆柱壳。

Underwater Acoustic Radiation of Gas-bag Coated Water-Filled Cylindrical Shell

In order to reduce the underwater radiated noise of water-filled cylindrical shell (WCS) excited by an interior point acoustic source, a gas-bag is coated on the outer surface. In order to give instructions on the design of gas-bag coated water-filled cylindrical shell (GCWCS), the bare and gas-bag coated WCS are respectively simplified into single- and double- leaf partitions. By comparing the wave impedances of the partition, gas and water, influences of the sound velocity and thickness of gas on the low frequency radiation of double-leaf partition are analyzed. It is shown that gases of smaller sound velocity and proper thickness have better noise reduction effect. The acoustic infinite element method is employed to calculate the underwater acoustic radiation of GCWCS, whose results are in good accordance with those of partitions. The underwater radiated power and sound pressure of the optimized CO2-bag coated WCS are much lower than the bare one.