声呐罩夹芯式透声窗的声学设计研究

Design of sandwich acoustic window for sonar dome

以船舶声呐罩透声窗的低噪声设计为背景,针对由粘弹性夹芯平板和平行腔体组成的简化声呐罩模型,采用双重Fourier变换方法和波数一频率谱分析,建立平稳随机湍流脉动压力激励下三层夹芯式透声窗在声呐基阵部位产生的自噪声计算方法,数值分析了透声窗几何和物理参数对自噪声的影响,提出夹心式透声窗声学设计的方法和参数。研究结果表明:三层夹芯式声呐罩透声窗的低噪声特性主要取决于夹芯粘弹性层中纵波和横波传播的截止效应以及阻抗失配效应。通过对弹性平板和粘弹性层的厚度、密度、杨氏模量、阻尼因子以及粘弹性层的纵波和横波声速等参数的合理选取,可以使夹芯透声窗比单层透声窗的降噪效果最大增加6.5dB。

Aimed at the low noise designing of sonar dome in ships, it had been established that a method of calculating the self noise of sonar array for a simplified sonar dome consisting of sandwich plate of visco-elasticity and parallel acoustic cavity, which is induced by acoustic window of sandwich excited by stationary random fluctuation force of turbulence boundary layer, using temporal and spatial Fourier transform and wave number - frequency spectrum analysis. After numerically analyzing the influence of geometrical and physical parameters of acoustic window on the self noise, it is suggested that the design method and reasonable parameters for acoustic window of sandwich. The results show that the property of low noise induced by acoustic window of sandwich is dominated by the cut-off effect of longitudinal wave and transverse wave propagating in the visco-elastic layer of sandwich as well as the mismatch effect of impedance. If the thickness, density, Young＇s modulus and damping factor of plates and visco-elastic layer as well as the sound speed of longitudinal wave and transverse wave in visco-elastic layer are selected reasonably, the maximum noise reduction of acoustic window of sandwich is 6.5 dB greater than that of a single glass fibre reinforced plastic plate.