船舶和水下航行器尾流感应电磁场建模及可探测性研究

The studies on induced electromagnetic of ship wakes mechanism, mathematic model and experimental is an important part of the optical properties of characteristic research for ship electromagnetic field and is an new research direction for the studies of the underwater remote detection and the target detection and the identification of the target feature. It is an important tool to improve the probability of detection and lower false alarm rate. First, this study will intend to divide the induced electromagnetic of ship wakes into four types taking the air, sea and seabed into consideration, then establish the two layer and three layer mathematic models of the electromagnetic fields induced by ship and submerged vehicle wakes. On this basis, though the establishment of the noise model of the electromagnetic field associated with wave motion, the detectability of induced electromagnetic of ship wakes will be analysed. Finally, the electromagnetic fields induced by ship wakes detection experimental system will be built. The above models will be corrected and validated through experiments. The characteristic of induced electromagnetic field will be got. This study is of great significance for elucidating the mechanism and the characteristic of induced electromagnetic of ship wakes. It has important significance of values of academic and engineering applications for electromagnetic detection buoy, underwater warning detection device and other fields.

船舶和水下航行器尾流感应电磁场产生机理、数学模型及实验研究是船舶和水下航行器电磁场特性研究的重要组成部分，也是水下远程探测和目标特性识别研究的新方向，是提高探测系统探测概率、降低虚警率的重要手段。首先，本课题拟将船舶尾流感应电磁场分为四种类型，并考虑空气、海水和海底三层介质的影响，基于流体力学理论和麦克斯韦方程组，建立船舶尾流感应电磁场的两层和三层模型，以及水下航器尾流感应电磁场的两层和三层模型。在此基础上，通过建立海浪感应电磁场噪声模型，利用高斯积分法求解尾流感应电磁场模型，分析尾流感应电磁场在不同海况下的可探测性。最后，拟构建尾流感应电磁场探测实验系统并开展实验研究，修正、验证上述模型，得到船舶及水下航器尾流感应电磁场的相关性质。本项研究对阐明尾流感应电磁场的产生机理及特性有重要意义，对海上电磁探测浮标、水下预警探测装置等领域也具有重要的学术和工程应用价值。

尾流具有持续时间长、传播距离远且难以模拟和消除的特点，可以为船舶及水下航行器的探测提供新的手段，项目以船舶及水下航行器尾流感应电磁场的建模及可探测性研究为背景。.明确了船舶及水下航行器尾流感应电磁场的产生机理；建立了水面船舶尾流感应电磁场数学模型，特性分析表明尾流感应电磁场水下具有良好的特性：信号量级可观、低频率、距离越远幅值衰减速度越小，且功率谱为线谱，频率在0.5Hz以下，可用于船舶的远程水下探测；实例仿真表明：尾流感应磁场的量级与速度密切相关，航速增加，则尾流感应电磁场的量级随着迅速增加；尾流感应磁场量级可达nT级，感应电场量级可达数十uV/m。建立了水下航行器尾流感应电磁场数学模型，并证明了两层模型可由三层模型直接求得，以美国Los Angeles级核潜艇为例进行了实例仿真计算，结果表明：水下航行器尾流感应电磁场的大小与排水量、航速和潜航深度有关，航速越高、航行深度越浅感应电磁场的强度越强；潜艇航速越高，感应电磁场频率越低，频率集中在 Hz量级；若不考虑海水深度，潜艇以10m/s速度在30m深度航行时，水下10m近处尾流感应磁场可达0.1nT的量级，尾流感应电场可达uV/m量级；考虑海水深度为60m时，尾流感应磁场量级可达3nT，尾流感应电场可达uV/m量级。建立了海浪感应电磁场数学模型，并分析了尾流感应电磁场的可探测性，结果表明：海浪感应电磁场频率集中在0.5Hz以下；尾流感应电磁场的量级均能高于目前电磁场传感器的测量门限，是可被探测到的，但其频谱和海浪感应电磁场的频谱十分接近，在低信噪比下提取目标信号具有一定难度。.进行了实验室和海上试验验证。试验表明：海浪感应电场量级可达uV/m，感应磁场量级可达0.5nT，能量集中分布在DC~0.5Hz的频带范围内，量级和频段均与理论分析一致；实船舶尾流感应电磁场是可探测的，被测船舶尾流感应电场信号频率在0.15Hz附近。试验结果表明了理论分析的正确性，该项目的研究成果可为船舶及水下航行器尾流感应电磁场的应用提供理论支撑。