珊瑚型环礁斜坡地形水下声传播特性分析

Analysis of underwater acoustic propagation characteristics of coral reef slope topography

从岛礁斜坡地形条件下的声信号衰减和地形阻断效应分析出发,重点针对水下声场分布规律及其对声传播造成的影响开展研究。利用水声模型理论,结合某礁实测地形以及水文数据,建立岛礁斜坡地形下的多途声信道模型,基于Bellhop与RAM声学仿真方法,对不同地形下的声线轨迹、声传播损失以及信号时延等声场特性进行仿真分析,得出岛礁斜坡地形下的声场分布特征。研究结果表明:(1)岛礁斜坡地形是影响其声传播模式的关键因素;(2)斜坡外缘浅海区域的目标不易被岛礁斜坡顶端的声呐所探测;(3)陡坡地形对浅海声源的声传播有利,当声源深度足够大时,缓坡地形下的本征声线数目能够达到在陡坡地形下的5倍,对声传播有利。以上研究结果可为岛礁区水下声场的特性分析以及水下声学对抗等实践应用提供理论基础和技术参考。

Based on the analysis of acoustic signal attenuation and terrain blocking effect under the condition of is-land and reef slope terrain,the distribution of underwater acoustic field and its effect on sound propagation are studied.A multi-path acoustic channel model is established by using the theory of acoustic model combining the measured topography and hydrological data.In addition,based on the Bellhop and RAM acoustic simulation method,the sound field characteristics of different terrains,such as sound rays traces,sound transmission loss and signal delay,are simulated,and the distribution characteristics of sound field under the condition of island and reef slope terrains are obtained.The results show that:(1)The slope topography of the reef is the key factor that affects the acoustic propagation modes;(2)The target in the shallow water area on the outer edge of the slope is not easy to be detected by the sonar at the top of the reef slope;(3)The steep slope terrain is good for the sound propagation of the sound source in shallow water,however,when the sound source depth is large enough,the gentle slope terrain is more conducive to sound propagation,and the number of eigenrays in the gentle slope terrain can reach 5 times of that in the steep slope terrain.The research results can provide theoretical basis and technical reference for the characteristic analysis of underwater acoustic field and the underwater acoustic countermeasure in island and reef areas.