水下不同边缘扁平结构散射声场特性研究(英文)

Investigation on the Characteristic of Scattering Field Distribution for Underwater Flat Structure with Different Edge Shapes

鉴于实际中存在的水下扁平结构的边缘特点,也为研究不同边缘附加结构形式对其散射声场的影响规律,并为边缘衍射效应影响抑制机理与技术等奠定基础,本文通过采用边界积分方法和边界元数值计算技术,并结合水下目标散射强度估计和水声无源材料自由场测试等工程实际,对不同边缘结构形式的水下扁平结构在不同频率范围和空间几何配置条件下的散射声场分布规律开展了定量的研究与分析。研究结果表明:在发射声源与结构几何配置等条件一定的情况下,无论前向散射还是镜向散射,附加边缘结构扁平矩板结构散射声场在频域和空间分布趋势上与未附加边缘结构的基本一致,即低频段起伏较小,而中高频段则波动较为剧烈,与结构距离越近越剧烈,这在前向散射中表现得尤为明显,其与波贡献主要成分、附加边缘的结构类型、边缘结构附加方式、结构参数、声波相干作用和边缘重数等因素密切相关。

Due to the fact that a certain edge shape is always appended to the underwater nat structures, in order to investigate the influence of different typical edge shapes on the scattering field, and lay a foundation for the research of suppressing technique of the edge -diffracted effect, the Boundary Integral Method （BIM） and the Boundary Element Method （BEM）, combined with the underwater target strength estimation and the measurement for underwater acoustical passive material in the free field,are applied to study and analyze the characteristic of scattering field distribution quantitatively in different frequency ranges and spatial geometrical configurations for underwater fiat structures with different edge shapes.The results show that when the geometrical configuration of the emitting sound source and the structure are unchanged, no matter the forward scattering or the mirror scattering, the distribution trend of scattering field of the flat rectangular structures with appended edge structure in frequency ranges and spatial distribution accords basically with the flat rectangular structures without appended edge structure. That is, the fluctuation is very slender in low frequency, while very acute in mid and high frequency; especially more acuter when the receiving point is in the neighborhood of the structure, which is more obvious in the forward scattering.And these are concerned with some factors such as the main contribution part of the wave field,the shape of the appended edge structure, appended mode of edge structure, structural parameters, the coherence effect of acoustical wave, the number of edge layer, and so on.