Abstract：The insulator of electromagnetic rail launcher is prone to thermal damage under transient launch conditions, which affects the support strength and insulation performance. At present, the research on thermal damage of the insulator is mainly focused on two-dimensional transient simulation and the description and analysis of experimental phenomena, without considering the thermal effect of time-space variation of rail heat caused by armature motion on the insulator, and there is a lack of research on the thermal erosion mechanism of the insulator in fluid-solid-thermal coupling environment. Therefore, this paper uses a three-dimensional transient electro-magnetic-thermal coupling model to analyze the influence of rail heat varying with time and armature position on the insulator. A fluid-solid-thermal coupling model considering the meso-structure of G10 insulator is established to explain the thermal erosion mechanism of muzzle arc blowback on the insulator, which is verified by experiments. Firstly, the governing equation of transient electromagnetic field, thermal diffusion equation and armature motion equation in the armature in-bore launching stage are established, in which the armature motion is realized by changing the material properties of the armature motion area. The geometric model of the launcher is constructed and the boundary conditions of magnetic field, electric field and temperature field are applied. Secondly, the turbulence equation of muzzle arc blowback stage is established, and the meso-model of G10 insulator reinforcement (yarn) and matrix (resin) is constructed, and the fluid boundary conditions and solid and fluid heat transfer boundary conditions are applied. Finally, the experimental phenomenon of the prototype is compared with the law of thermal erosion obtained by simulation. The simulation results show that under the condition of single launch, the maximum temperature of the insulator inner surface in contact with the rail is 401 K in the armature in-bore launching stage, which is close to the maximum allowable working temperature. In the muzzle arc blowback stage, only the insulator yarn within the range of muzzle 1.3 mm reaches the thermal decomposition point, and the thermal erosion depth decreases gradually from 0.125 mm at muzzle 0 mm to 0 mm at muzzle 1.3 mm. The insulator resin within the range of muzzle 10 mm reaches the thermal decomposition point. The thermal erosion depth decreases slightly along the breech, the deepest at muzzle 0 mm is 0.125 mm, and the average erosion depth is about 0.07 mm. The following conclusions can be drawn from the simulation analysis: (1) In the armature in-bore launching stage, the high temperature area of the insulator extends to the muzzle with the armature movement, but the temperature from the breech to the muzzle decreases gradually, and the highest temperature always appears near the starting position of the armature, which is close to the maximum allowable working temperature of the insulator. (2) In the muzzle arc blowback stage, the blowback arc has little effect on the insulator yarn and only causes "chamfer" thermal damage to the yarn within the range of muzzle 1.3 mm. However, it causes a large-scale thermal decomposition to the resin in the area where the arc flows on the inner surface of the insulator, and the thermal decomposition damage of the resin is dominant. The experimental phenomenon is consistent with the law of thermal erosion obtained by simulation. (3) Continuous launching will lead to the accumulation of insulator temperature, and the design of rail cooling system can avoid the decrease of the support strength of the insulator. Arc blowback will bring carbonization and metal pollution on the inner surface of the insulator. The use of muzzle arc suppression device and the improvement of the thermal erosion resistance of the resin are helpful to avoid insulation failure.
胡鑫凯, 鲁军勇, 李白, 谭赛, 张嘉炜. 瞬态条件下电磁轨道发射装置绝缘体热损伤分析[J]. 电工技术学报, 2023, 38(21): 5673-5681.
Hu Xinkai, Lu Junyong, Li Bai, Tan Sai, Zhang Jiawei. Thermal Damage Analysis of Insulator in Electromagnetic Rail Launcher under Transient Conditions. Transactions of China Electrotechnical Society, 2023, 38(21): 5673-5681.
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2023, Vol. 38 
