舰船螺旋桨空泡噪声的数理模型

Theoretical model of noise caused by ship propeller cavitation

探讨舰船螺旋桨空泡噪声指数衰减型随机脉冲序列的理论模型。据此理论模型，导得螺旋桨空泡噪声谱的表达式。结果表明，螺旋桨空泡噪声由连续谱和离散线谱组成。螺旋桨空泡噪声线谱的相对幅值取决于声脉冲前沿出现时刻的随机摆幅。高频时线谱成分趋于零，低频段线谱成分甚大于相应的连续谱成分。高频段连续谱随频率的平方而下降，低频段连续谱随频率的平方而上升，在某一较低频率处出现谱峰。上述螺旋桨空泡噪声谱特性的理论结果和实际观测数据之间具有很好的一致性。

The present paper deals with theoretical model of random sequence of exponential attenuate acoustic pulses caused by ship propeller cavitation noise. On the basis of above theoretical model, the spectrum formula of propeller cavitation noise has been derived. It is shown that propeller cavitation noise is composed of continual spectrum and separable line spectrum. The line spectrum relative amplitude ofpropeller cavitation noise is depended on random swing of acoustic pulse front edge generation moment. At high frequency line spectrum components in noise approach to zero, and in lower frequency region line spectrum was much large than correspondent continual spectrum. The continual spectrum decreasewith frequency as inverse square law at high frequency, and increases with frequency square in lowerfrequency, and the spectrum peak is existed in certain lower frequency. The agreement between abovementioned theoretical results and existent measured data is very good.