Simulation And Experimental Research On Debye Magnetic Field Excited By Jet Fluid

With the development of low-magnetic materials and degaussing technology,the ferromagnetic magnetic field of submarine is gradually decreasing,thus the difficulty of submarine detection is increasing.It is urgent to study a new target magnetic source.Moving submarine will disturb the flow field,and cause the separation of positive and negative ions in the sea,producing magnetic field called Debye magnetic field.It has nothing to do with the submarine’s own magnetism.It will exist once the submarine is sailing.Therefore,it is an ideal magnetic source for detection.However,the generation mechanism and distribution law of Debye magnetic field are not clear yet when applied into submarine detection.Moreover,there are problems such as high cost and difficulty to directly carry out submarine Debye magnetic field test.This paper aims to establish a scientific and reasonable Debye magnetic field research method to provide technical support for submarine detection based on Debye magnetic field.Firstly,considering the physical and chemical environment of seawater and ion dynamics,a theoretical model of the Debye magnetic field in the marine environment is established.According to the theoretical model,the excitation conditions of the Debye magnetic field are revealed,which is,the excitation source needs to generate a time-varying,eddy current,and high-energy flow field.Based on that,the jet fluid is selected as the excitation source of the Debye magnetic field.Secondly,based on the established Debye magnetic field model,a flow field-magnetic field integrated joint simulation platform was built,and the Debye magnetic field was modeled and calculated for two modes of continuous jet and periodic jet.The simulation results show that when the jet diameter is 3.5mm and the flow rate is 60L/min,the continuous jet mode can excite the Debye magnetic field with a signal power of1.423n T~2 at a measuring point of 0.5m,and the signal power shows increasing trend as the concentration increases.In the periodic jet mode,the peak-to-peak value of the Debye magnetic field can reach 0.0451n T,and the Debye magnetic field shows a decay trend with increasing distance.Finally,a Debye magnetic field test system was designed from the aspects of power device,magnetic shielding device,water pump pipeline and detection device,and a signal detection method was designed according to the characteristics of Debye magnetic field signal under different jet modes.In the continuous jet mode,the flow field is a turbulent flow without obvious frequency characteristics,so a Debye magnetic field evaluation method based on power spectrum integration is proposed;in the periodic jet mode,the flow field has clear periodic characteristics,so a Debye magnetic field amplitude estimation method based on spectral characteristics is proposed.The test results show that the signal power of the Debye magnetic field excited by the continuous jet can reach1.338n T~2,and the peak-to-peak value of the Debye magnetic field excited by the periodic jet can reach 0.0323n T,and the spatial distribution and the law of changes with concentration are consistent with the simulation results.The established joint simulation platform and test method can provide strong technical support for submarine detection research based on Debye magnetic field.