水中目标自由场声辐射特性还原及远场声辐射热区识别

获取水中目标的声特性对目标识别和分析十分重要。为解决水中目标声特性测试中自由场条件难以实现的问题，消除结构表面能量流对远场声辐射热区识别的干扰，提出结合基于边界元自由场还原技术和表面贡献法的声场分离技术，实现水中近场非自由场环境中获取水中目标的声特性和识别远场声辐射热区。数值模拟结果表明：非自由环境下基于边界元的声场还原方法还原得到的声场声压、声功率等特性，与直接在自由场获取的结果基本相同；进一步利用表面贡献法过滤掉循环于振动结构表面的能量流，能够在近场识别远场辐射热区。该方法突破了测试环境限制，可大幅降低测试费用，具有一定的工程应用价值。

The Recovery of Underwater Target's Free Field Acoustic Radiation Characteristics and Identification of Far-field AcousticRadiation Hotspot

Acquiring the acoustic characteristics of target in water is very important for the identification and analysis of a target. A field separation technique combined sound field recovery technology based on boundary element method with surface contribution method is proposed to achieve the free field conditions for testing the sound characteristics of target in water and eliminate the interference of the energy flow at the surface of structure to the identification of hotspot in the far-field acoustic radiation. The proposed method can be used to obtain the free field acoustic characteristics of the underwater target in the non-free and near field environment and identify hotspot in far field in water. The simulated results show that there are no significant differences among the sound pressure and sound power obtained by the sound field recovery technology and those in the free field. The surface contribution method is used to filter out the energy flow circulating on the surface of vibrating structure, so far-field acoustic radiation hotspot can be identified in near field. The proposed method breaks through the limitations of test environment, significantly reduces the testing costs and has certain engineering application value. Key