Research On The Shielding And Utilization Of Electromagnetic Railgun's High Magnetic Field Environment

The application of electromechanical fuze in electromagnetic railgun can achieve the control of ammunition and maximize the damage efficiency of electromagnetic railgun ammunition.Research on dynamic characteristics of projectile during the launching process of electromagnetic gun is the basis of fuze design.Besides,reasonable protective measures should be taken to improve the working reliability of control circuit in electromechanical fuze for electromagnetic railgun in-bore high magnetic field.Based on this research background,this thesis carries out research on the shielding and utilization of electromagnetic railgun's high magnetic field environment for electromechanical fuse.The research contents are mainly related to the following aspects.In order to study the change characteristics of the in-bore magnetic field during the launching processes of the electromagnetic railgun,first of all,the dynamic analysis of the armature is carried out.In consideration of the nonlinear variation of the inductance gradient and the resistance gradient,the armature movement equations are established.And then the curves of armature force,velocity and displacement are obtained by solving the armature movement equation.According to the instantaneous synchronization of exciting current amplitude,frequency and the armature displacement,the raigun's launching parameters of different time are set up.Then Maxwell eddy current solver is utilized to achieve dynamic simulation of magnetic field and get time-varying characteristic and spatial distribution characteristics of railgun in-bore magnetic field.Armature dynamic characteristics and magnetic field characteristics provide basis for design of electromagnetic gun fuze safety system.In order to improve the viability of electromagnetic fuze in the low frequency strong magnetic field of electromagnetic railgun,researches on passive shielding scheme are imperative.Based on analyzing the influence of shielding material,structure,position and bottom hole shape on the shielding effectiveness,the optimal shielding scheme can be designed.The simulation results show that the average peak flux density of inspection surface in the optimized shield is about 0.0028T,and the shielding effectiveness of the inspection surface reaches 37.33dB.The control circuit in electromechanical fuze can work reliably in the weak magnetic field after shielding.According to electromagnetic induction theory,we can present the proposal of induction coil as the power supply for electromagnetic fuze and analyse the feasibility,based on in-born specific magnetic field of the electromagnetic railgun.By investigating the influence of coil radius,position and turn number on the induced electromotive force,the coil structure is optimally designed.According to the time domain variation characteristics of induced electromotive force and induced current generated by the coil,the energy storage and voltage stabilizing circuit of electromagnetic fuze power supply is designed,and the optimal scheme of steady voltage is determined by the energy storage experiment.