| Electromagnetic railgun,which have the advantages of fast response,high power,and precise controllability,can be widely used in the military field,aerospace field and so on.In recent years,there have been a lot of theoretical research on electromagnetic railgun,but there are still some problems to be solved if it is to be applied in practical engineering.During the electromagnetic railgun launching process,the pulse current flows through the metal rail to generate Joule heat,and at the same time,the armature slides at a high speed relative to the rail to generate friction heat.The continuous accumulation of these heat will have an adverse influence on the performance and life of the railgun.Therefore,it is of great significance to study the source of accumulated heat in the rail,the mechanism of heat generation,and the transient temperature effect of the rail in the process of electromagnetic emission.The simulation method is used in this study due to the limitation of the condition.Firstly,three kinds of heat sources of the temperature rise of the rail are theoretically analyzed,and their curves over time are obtained by analytical method.The three kinds of heat all show a non-linear growth trend and tend to be stable at last;Then,the mathematical model of electromagnetic field and temperature field of electromagnetic railgun is analyzed.On this basis,a three-dimensional coupled model of transient electromagnetic field and temperature field is established by using the finite element analysis software Comsol.The simulation results show that the rail temperature distribution is basically the same as the current density distribution.In the contact area between the rail and the armature,they are all concentrated in the direction of the tail of the armature,and in the cross section of the rail,they are concentrated in a thin layer of 1～1.5 mm inside the rail.In addition,the time-varying characteristics of the rail temperature are also obtained.With the diffusion of current,the temperature distribution is gradually uniform,and the temperature of each point on the rail increases monotonously with time,and then decreases slightly due to the current drop.The simulation results can provide theoretical basis for the design position of cooling pipes in the rail;Finally,under the condition of control variables,the influences of input current peak value,current waveform,rail material,rail size and armature size on the rail temperature are studied.The conclusions can provide reference for the optimal design of electromagnetic launch device. |
