Analysis on Thermal Character of Interface Between Rail and Armature for Electromagnetic Railgun

The thermal character of the interface between rail and armature significantly affects the launch performance of electromagnetic railguns. In this paper, the friction coefficient mu between brass and aluminum is discussed; it is found that, under hypervelocity and electrical contact conditions, mu maintains an order of magnitude of 10(-2) or less, which is smaller than that under normal conditions. A 2-D simulation model is developed to analyze the temperature character of armature contact surface caused by friction, and the simulated results concretely demonstrate the order of magnitude of mu when armature is launching in bore. Another 3-D simulation model is also developed to obtain the temperature distribution on the armature contact surface under high current. According to simulation results of interface temperature distribution, the thermal effect on armature wear and contact performance is analyzed. For an electromagnetic railgun with hypervelocity and high current, it is concluded that the heat generated by friction and high current can cause armature surface film to melt and cause armature edges of ends to be damaged. The aluminum film is helpful to improve the contact performance.