考虑温度影响的电磁轨道发射装置温度场与热应力分析

Temperature field and thermal stress analysis of electromagnetic rail launcher considering temper considering temperature effect

为探究温度对电磁轨道发射装置电枢电流密度和温度场的影响,分析了发射装置的热载荷来源,建立了电枢温度场理论计算模型,并对其进行求解。用脉冲成形网络对发射装置供电,采用有限元法,求出接触电阻随时间的变化曲线,在考虑电磁场-温度场-应力场等的情况下建立三维有限元计算模型,对比分析理想接触状态下、仅考虑接触电阻、既考虑接触电阻又考虑温度影响的3种状态下的电流密度、温度场及热应力。结果表明:3种状态下电枢最大电流密度的变化趋势相同,均为先急剧增大再急剧减小再缓慢减小,电枢最高温度和最大应力的变化趋势也相同,均为先缓慢上升再迅速上升最后缓慢减小趋于稳定,但考虑接触电阻与温度影响下的电枢最高温度和最大应力的峰值时间推迟,峰值增大;在发射过程中,电枢尾部首先开始熔化,随后热量向头部传播,在间隔0.3 ms后整个接触区域温度均超过熔点,电枢尾翼熔化厚度约为0.25 mm,接触电阻产生的热量发生在电枢臂尾翼纵向0.7 mm区域内。

In order to investigate the influence of temperature on the armature current density and temperature field of electromagnetic rail launcher,the source of thermal load of the launcher was analyzed,and the theoretical calculation model of armature temperature field was established and solved.The pulse forming network was used to supply power to the transmitter.The change curve of contact resistance with time was obtained by finite element method.A three-dimensional finite element model was established considering the electromagnetic field-temperature field-stress field,etc.The current density,temperature field and thermal stress in the ideal contact state,considering only the contact resistance,considering both the contact resistance and the influence of temperature were compared and analyzed.The results show that the maximum current density of armature has the same variation trend under the three states,firstly increasing sharply,then decreasing sharply and then decreasing slowly.The maximum temperature and maximum stress of armature also have the same variation trend,firstly rising slowly,then rising rapidly and finally decreasing slowly and becoming stable.However,considering the influence of contact resistance and temperature,the peak time of the maximum temperature and maximum stress of armature is delayed and the peak value increases.In the launching process,the armature tail first begins to melt,and then the heat spreads to the head.After an interval of 0.3 ms,the temperature of the entire contact area exceeds the melting point.The melting thickness of the armature tail is about 0.25 mm,and the heat generated by the contact resistance occurs in the longitudinal 0.7 mm area of the armature arm tail.