散射和反射界面影响下水听器阵列超指向性研究

The contradiction between array size and performance for traditional arrays is becoming more and more prominent because of the quiet underwater targets and their radiated low-frequency noise. The superdirectivity theory is significantly attractive and have good potential of being applied in practice, because it can provide high directivity, good angular discrimination, and remarkable reduction of array aperture. Although the related researches are fruitful, an in-depth study of superdirectivity for hydrophone arrays in a practical environment is still desired. Actually, hydrophone arrays are always affected by scattering boundaries in their fixed platforms or reflecting boundaries in their deployed scenarios. This project is focused on developing superdirectivity models for hydrophone arrays in the presence of a scattering or a reflecting boundary. The specific superdirectivity expressions will be formulated based on the established sound scattering and reflecting models. Then, the robust superdirective methods will be proposed and the relations between its performance and boundary properties should be summarized. The experiments will be carried out and the results will be compared with the theoretical ones. The proposed robust superdirective methods should be further improved based on experimental results, which will be significant to enhance the performance of small hydrophone arrays in the presence of a scattering or a reflecting boundary and give theoretical guidelines to design new sonar systems.

随着水下目标的安静化、辐射噪声的低频化，传统水听器阵列的探测能力与其尺寸之间的矛盾越来越突出。超指向性可有效提高水听器阵列探测的信噪比增益和方位分辨力，且能大幅度减小阵列的尺度，具有很好的应用前景。虽然相关研究已取得丰硕成果，但仍然缺乏对实际环境中水听器阵列超指向性的研究。很多应用中，水听器阵列会受到安装平台和布放环境中存在的散射和反射界面的影响。本项目拟针对这一具体情况，通过构建散射和反射界面影响下的声场模型，给出水听器阵列超指向性解的具体形式，提出稳健处理方法，并总结其性能随散射和反射界面性质变化的规律。在仿真研究的基础上，进行实验验证，依据实验结果进一步优化稳健处理方法，为提高散射和反射界面影响下小尺度水听器阵列在分辨力、信噪比增益等方面的性能提供技术支撑，对我国新型声纳的设计具有重要意义。

实际水声应用中，水听器阵列会受到安装平台和布放环境中存在的散射和反射界面的影响。如果不考虑界面影响，超指向性方法的优越性能将难以保证。本项目深入研究了界面散射和反射声场的计算方法，建立了多种适用于界面影响下水听器阵列的超指向性模型，提出了一系列稳健优化方法，并进行了实验验证。主要研究成果包括：（1）研究和提出了圆柱形散射界面声场解析计算方法、任意散射界面边界元数值计算方法、复杂散射界面实验测量方法、平整反射界面声场解析计算方法。（2）建立了界面影响下水听器阵列的特征波束分解与综合、Gram-Schmidt模态波束分解与综合、波束图综合等三种超指向性模型，给出了界面影响下窄带和宽带超指向性的解析闭式解，提出了降秩和优化等稳健处理方法，获得了稳健超指向性结果。（3）针对圆柱形散射界面影响下的直线阵、圆柱阵和圆环阵，仿真研究了界面为刚性和弹性时超指向性方法的波束图、指向性和稳健性；针对直线阵，研究了刚性、压力释放和典型海底等三种不同性质反射界面影响下超指向性方法的波束图、指向性和稳健性。（4）研究了超指向性方法的指向性和稳健性随阵列与界面距离、界面材料特性等因素的变化规律。.本项目完成了所有预期研究内容，取得了丰硕成果。在本项目的支持下，发表论文17篇，其中SCI论文7篇，申请专利5项，完成专著1部。项目部分研究内容得到了消声水池实验的验证，相关方法已应用于海洋环境噪声测量、水下目标探测等领域，取得了良好的应用效果。