空气中声源激发水下声场的水平纵向相关性

声场的空间相关特性是声场的重要特征,对水下探测、水声通讯等各种设备在实际海洋环境中应用的参数选择具有重要意义,是水声工程技术研究的重要基础之一。相比于水中声源激发声场的相关特性研究,空气中声源的相关研究很少。本文推导了空气中声源激发水下声场的水平纵向相关的简正波表达式,并通过数值仿真分析,比较了声源分别位于空气中和水中时水下声场的水平纵向相关特性。对南海海域进行的一次悬挂汽笛空气声源、海底水平阵接收信号海上实验获得的数据进行分析,结果表明:空气中声源位于不同距离时,其发射的声信号激发水下声场的水平纵向相关均存在明显的起伏结构,基于本文提出的空气中声源激发水下声场的水平纵向相关系数的简正波表达式能够较好地解释该现象. 

Acoustic longitudinal horizontal correlation of air-to-water transmission

Spatial correlation is an important characteristic of underwater sound field, which is relevant to underwater localization, underwater communication and serves as a useful and efficient tool for predicting the performance of large acoustic arrays. Compared with spatial correlation of sound field excited by a waterborne source which has received lots of attention, there are few researches about the airborne source. Based on the normal-mode theory, a mathematical expression for longitudinal horizontal correlation coefficient of underwater sound field excited by an airborne source is derived in this paper, and a simulation is employed to compare the longitudinal horizontal correlations for source in air and in water. An air-to-water experiment was conducted in the South China Sea, and signals transmitted by a hooter hung on a research ship were received by an underwater horizontal line array during the experiment. It is shown that, for underwater sound field excited by the airborne source at different distances, the longitudinal horizontal correlation coefficient has an evident oscillation structure, which is explained by the proposed mathematical expression.