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《Ship Building of China》 2008-03
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An Investigation of Sonar Self Noise for Periodically Stiffened Sandwich Acoustic Window

YU Meng-sa,LI Dong-sheng,BAI Zhen-guo(China Ship Scientific Research Center Wuxi Jiangsu 214082,China)  
Aimed at the low noise design of sonar dome in ships,a methed is presented for calculating the hydrodynamic component of sonar self noise in a simplied sonar dome consisting of periodically stiffened sandwich acoustic window and parallel acoustic cavity,which is excited by stationary random fluctuation pressure of turbulence boundary layer,using spatial FOURIER transform and the wavenumber-frequency spectrum analysis.The influence of geometrical parameters and distance of ribs in the stiffened sandwich acoustic window on the sonar self noise is analyzed numerically.The results show that the sonar self noise for the case of stiffened acoustic window excited by the fluctuation pressure under turbulence boundary layer depends on the spatial filtering of sonar dome.When the wavenumber response peak of the sonar dome coincides with the convective peak of the wavenumber-frequncy spectrum of the fluctuation pressure under turbulence boundary layer because of the wavenumber transfer caused by scattering mechanism of ribs,the sonar self noise obviously increases.But the cut-off effects of elastic wave propagating in the visco-elastic layer of stiffened sandwich acoustic window partly compensate spatial modulation effect of the ribs,so that the sonar self noise would decrease 5dB~10dB.
【CateGory Index】: U666.7
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