Objective The induced electromagnetic properties brought forth by disturbed seawater cutting the geomagnetic field can provide important information for non-acoustic detection technologies. In view of the complex and highly nonlinear interaction between the flow field and electromagnetic field of a high-speed submarine, it is necessary to deeply analyze the influence of the turbulence structure caused by natural cavitation on the induced electromagnetic field.
Methods First, a multi-physical field mathematical model of fluid-electromagnetic coupling is established on the basis of hydrodynamics and electromagnetics. Next, the intensity and range of near-field electromagnetic signatures in the cavitation evolution, and the time-frequency characteristics of the induced electric field under different cavitation numbers, are obtained through numerical simulation using Fluent software.
Results The simulation results demonstrate that the electromagnetic field shows obvious quasi-periodic unsteady fluctuation features due to the evolution of the cavitation morphology. The magnitudes of the induced electric field and magnetic field are 10−1 mV/m and 10−2 nT respectively, which are within the detection range of the most sophisticated sensors. Additionally, the cavitation number is highly correlated with the time-frequency characteristics of the induced electric field. When the cavitation number decreases from 0.4 to 0.2, the fluctuation intensity of the induced electric field is significantly enhanced, its main frequency decreases from 49.94 Hz to 34.19 Hz, and the low-frequency fluctuation component increases accordingly.
Conclusion The induced electromagnetic characteristics of submarines can be employed to guide the non-acoustic detection of underwater moving bodies, and the main frequency range of the induced electric field can provide references for the electromagnetic communication frequency selection of high-speed submarines.
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