加速螺旋桨水声信号建模及其特性分析

Modeling and characteristic analysis of underwater acoustic signal of the accelerating propeller

加速或减速旋转螺旋桨的水声信号特征可用于被动探测与分类离靠港船只或水下航行器.文中从阐述螺旋桨匀加速旋转时尾流速度周向变化所具有的chirp周期特性出发,提出匀加速螺旋桨空化噪声的幅度调制包络可通过脉冲间幅度起伏的chirp周期高斯脉冲串信号予以建模,并给出了该模型的时域表达式.文中分析了chirp周期信号的简化分数阶Fourier变换谱特性,得到了在一定条件下chirp周期信号与其谐波系数间的关系式.文中通过水洞试验数据分析与仿真数据分析的比较,验证了匀加速螺旋桨噪声调制包络信号模型的合理性.

The signal feature of propeller cavitation noise during acceleration or deceleration procedure can be used to passively detect and classify moving vessels and underwater vehicles in the port regions.By analyzing the chirp periodicity of the variation of propeller wake velocity under acceleration situation,this paper presents the time domain expression of the modulation envelope signal of the accelerating propeller noise,treating thesignal as a Gaussian-shaped chirp periodic pulse train with increasing trend and fluctuating pulse amplitude.The paper investigates the characteristics of simplified fractional Fourier transform（SFRFT） spectrum of the chirp periodic signal,and thus obtains the relation between the chirp periodic signal and its chirp harmonics under the conditions of underwater passive detection.Furthermore,the experimental data of the cavitation tunnel satisfy the results obtained by simulation,which verifies the correctness of the proposed signal model.