作为体积目标的船舶声辐射纵向分布特性的研究

Research on Longitudinal Distribution Characteristics of the Radiated Noise of a Ship as a Volume Object

利用时频分析原理对船舶辐射噪声沿着船长的纵向分布特性进行了初步分析与实验研究 ,提出了一个简化的船舶声辐射三亮点模型。实验分析的结果证实了所假设纵向分布特性亮点模型的正确性。本文方法对研究船舶噪声起源及对船舶的声探测均有实际意义。

At short distance, the power spectrum characteristics of the ship radiated noise at different sections of the ship are different. Therefore, it is possible to identify the ship′s separate sections, to determine their bearings and ranges and to estimate the size of a ship. In this paper, we first proposed a “three high light spots” model to describe the longitudinal distribution of the radiated noise of a ship: ①In the stern, propeller is the principal noise source, and most of the energy exists in the frequency span of 1 000～5 000 Hz with strong continuous spectrum. ②In the section between the stern and the middle way , the noise energy is dominated by the propulsion machinery, and usually occurs within the frequency span of 10～100 Hz with low continuous spectrum and strong line components. ③In the midway, noise is mainly generated by auxilliary machineries and its frequency ranges from 100 Hz to 1 000 Hz with both continuous spectrum and line components. Then we did time frequency analysis of the passage characteristics of real ship radiated noise signal by short time Fourier transform. Analysis results (Figs.3 through 5 and Table 1) show that our model is correct.