强流脉冲下重复滑动电接触界面的电热特性

固体电枢电磁轨道发射中,膛内枢轨滑动电接触的电热特性关系到滑动界面的接触状态、电流传导品质和界面能量耗散,制约着系统效率和轨道寿命。设计开展了多组不同电流线密度的多发重复试验,通过采集电气试验数据进行迭代计算,得到了滑动接触电阻和界面焦耳热耗散功率的动态变化规律,分析了沉积物随重复发射的演变及电流线密度对电热特性的影响规律,并结合试验后轨道表面熔蚀沉积检测,讨论了滑动电接触界面的演变过程。结果表明:接触电阻稳定临界点和焦耳热耗散功率峰值点都出现在脉冲电流下降沿,接触电阻稳定值量级为10-2 mΩ,焦耳热功率峰值幅值可达10-1 MW;炮口速度随重复次数的增加而降低并趋于稳定,多次重复发射对滑动接触电阻和焦耳热功率较小的影响表明沉积物在发射中再次熔融并对电接触起积极作用;而即使输入能量一致,电流线密度的变化也显著影响了界面焦耳热的生成。

Electric and thermal characteristics of repeated sliding electric contact interface under high pulse current

In solid electromagnetic rail launcher, electric and thermal characteristics of sliding electric contact between armature and rails are related to contact status, current conduction and energy dissipation of sliding interface, influencing launcher system efficiency and rail lifespan. Many repeated launch test groups under different maximum linear current density were designed and carried out. Through iterative computation with test electric parameters, dynamic variation rule of sliding contact resistance and interface joule heat power were obtained, and effect of melt deposition evolvement and linear current density on electro-thermal properties were further analyzed. With inspection of melting deposition on rails after repeated tests, interface evolution process of sliding electric contact in gun bore was discussed. Results show that the steady critical point of sliding electric contact resistance and peak point of interface joule heat power both came up during current falling-edge. Contact resistance value of steady phase can be reduced in 10-2 m, and the maximum value of joule heat power can reach 10-1 MW. Contact resistance and heat power were affected hardly by repeated tests shows that deposition would re-melt and play positive role in sliding electric contact characteristic. Interface joule heat power was enlarged evidently by increasing linear current density even under the same input energy.