Simulation Study On Influencing Factors On Current Distribution In Large Caliber Railgun At Start-up Stage

Electromagnetic launch technology,with its military application prospects and huge potential,attracts the main military countries to study it on both theory and application.Armature takes an important role that affect the emission performance in the electromagnetic launch.It is difficult to directly observe all the physical quantities due to the extreme conditions in the emission process.Therefore,numerical simulation is the major way to study the characteristics.First,the electromagnetic diffusion model of the contact surface between the armature and the rail is analyzed under non-ideal contact conditions.In order to reveal the actual launch process,the electromagnetic diffusion model was coupled with the contact resistance model.In the simulation,the interface contact pressure distribution calculated by the structural mechanics module which coupled to the electromagnetic diffusion module through the contact resistance model.The non-ideal contact three-dimensional magnetic diffusion model is established.The influence of the contact pressure distribution and current distribution on the interface is carried out.And then two common used models which calculate the current distribution of contact surface are compared.Electromagnetic simulation model established by coupling the mechanical module with the electromagnetic module.The contact pressure distribution and current distribution on the contact surface between the armature and the rail can be obtained by the model.The factors which can affect the pressure distribution and current distribution on the contact surface is carried out,including the time of the current rise,the height and resistivity match of armature and rail.At the same time,the problem in the height match of armature and rail may occur during the actual launch is analyzed,and further optimization of the height matching between the armature and the rail were obtained.At last,The main parameters of the armature which can affect the contact pressure distribution and current distribution were analyzed,such as the radius on the tail,the length of the armature tail,the thickness of armature tail and the saddle parameter,the optimum arc radius were discussed by the method of the pressure distribution and current distribution on the contact surface.The problem of the saddle armature may occur during the actual launching process is analyzed,and further optimization of the saddle armature is made with the saddle armature with arc and the mixed saddle armature which were verified.