Design of sandwich acoustic window for sonar dome

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.