水下覆盖层结构的声学特性分析

Study on Acoustic Characteristics of Underwater Coating Structure

根据波动理论应用分层分析的方法得到了不同入射角度、不同背衬情况时声波在水下覆盖层结构中的吸声、反射系数以及透射损失等,并数值计算了不同入射角度下三种背衬条件下的透射损失,分析表明:声波垂直入射时透射损失性能最差;水背衬时水下覆盖层结构的透射损失低频时很小,中高频时急剧增加;单壳背衬低频时壳体本身起主要的吸收作用;中高频时水下覆盖层结构的吸收作用逐渐明显;双层壳背衬时其透射损失频响曲线出现谐振峰,削弱水下覆盖层结构的声学性能,总体来说,敷设非均匀结构要优于敷设均匀结构。

Based on wave-guide theory,the absorption coefficient,reflective coefficient and transmission loss of underwater coating structure in different backing conditions and incidence angles are provided by the method of delaminate analysis.The Transmission losses for five typical incidence angles are calculated.The result shows that the sound insulation performance of the structure for vertical incidence is very poor.The transmission losses under three backing conditions are calculated also.The result shows that transmission loss of the underwater coating structure for water backing is negligible in the case of low-frequency,while it increases rapidly in the case of medium and high frequencies.In the case of single-layer shell backing,the shell itself dominates the sound absorption of low frequency,while the underwater multi-layered structure becomes important gradually in sound absorption for medium and high frequencies.In the case of double-layer shell backing,the frequency response curve of transmission loss includes a resonance value,which deteriorates the acoustic characteristic of the underwater coating structure.Generally speaking,the sound insulation performance for laying non-homogeneous compound structures is much better than that for laying homogeneous compound structures.