Far-field characteristics and evolutions of electromagnetic field induced by the wake of underwater vehicles

Under the influence of the geomagnetic environment, charged seawater motion in the submarine wake generates a wake electromagnetic field, which is of great significance for underwater target detection and tracking. The generation of the wake electromagnetic field involves the coupling of multiple physical fields, such as fluid mechanics, ion transport, and electromagnetic fields, which have not yet been systematically studied. In this context, a coupling model involving the flow and electromagnetic fields is constructed to analyze the evolution of the far-field wake magnetic field of a full-size submarine propeller system. The flow field, current density, and far-field distribution of the wake magnetic field of the submarine propeller system at typical and rotational speeds are obtained. The three-component and total distributions of the far-field wake magnetic field are analyzed, and the longitudinal variation is discussed. The mechanism of the wake magnetic field is revealed based on this. In addition, the attenuation rule of the far-field wake electromagnetic field is studied, and the frequency characteristics of the far-field wake electromagnetic field are analyzed by a power spectrum. The results show that the wake electromagnetic field generated by the submarine propeller system in the far-field region has a wide distribution range (0.1 nT), and the corresponding frequency characteristics can be detected by a precision magnetometer. This study provides useful insight for the further evaluation of the far-field law of wake electromagnetic fields, which is conducive for future underwater target detection based on wake electromagnetic fields.