Heat Partition Process at Sliding Electrical Contact Interfaces with High-Speed and Large Current
Yao Jinming1, Fu Qiang2
1. College of Automation & College of Artificial Intelligence Nanjing University of Posts and Telecommunications Nanjing 210023 China; 2. Nari Group Corporation State Grid Electric Power Research Institute Nanjing 210023 China
Abstract:Aluminum deposition phenomenon occurs on rail's surface after a multishot at high-speed sliding electrical contact with a large current. The melt-wear of armature and deposited aluminum at the interface due to huge heat source's thermal effect can change contact condition, significantly affecting sliding electrical contact performance. The heat partition characteristics at interface between armature and deposited rail are crucial for investigating melting and wear of interface materials. Therefore, it is necessary to study the heat partition process at sliding electrical contact interface. Initially, this study established a thermal transfer model to derive the temperature distribution equations for armature and deposited rail. Control equation for heat partition is obtained by utilizing the principle of interface temperature continuity. Applying the least squares estimation method to optimize error function, a numerical calculation model for interface heat partition is proposed. Heat partition curves are calculated for varying material parameters based on numerical model for heat partition. Numerical results for heat partition's initial value are consistent with analytical solution. The results show that: the larger the heat absorption coefficient, the smaller the heat partition's initial value. As time progresses, the heat partition value is gradually decaying. While maintaining constant velocity, the heat partition decaying curves closely coincide across different material parameters. In order to study the effect of velocity on heat partition value, the actual launching velocity is compared with uniform velocity and uniform acceleration, assuming that three forms of motion reach 300 m/s at 0.5 ms. It can be found that heat partition is maximum for actual variable acceleration motion and is minimum for uniform velocity. At started-up stage for armature, velocity is maximum under uniform velocity and the heat partition curve decays faster, but as the velocity increases, the heat partition curve decays fastest in the actual variable acceleration case. It shows that the velocity curve determines the change trend for heat partition curve, the larger the velocity the smaller the heat partition, and the larger the acceleration the faster the heat partition decays. However, the heat partition values are also approximately equal when armature velocity are equal at the same moment. For example, if uniform velocity, uniform acceleration, and actual variable acceleration all reach 300 m/s at 0.5 ms, the heat partition values in the three forms of motions at the moment of 0.5 ms are all around 0.25. In the end, physical mechanism of the heat partition process at the interface between the armature and rail is discussed theoretically. It is found that the theoretical analysis results are consistent with the numerical calculation results. The following conclusions can be drawn from above analysis:(1) Heat partition value is related to launching velocity, material thermal parameters, contact length, and launching time. Material thermal parameters affect initial value of the heat partition curve and does not change its decaying rate. (2) Launching velocity affects the heat partition's decay rate, the larger the velocity the faster the heat partition decays with time. Under the same moment and velocity conditions, the heat partition value is equal. (3) During the entire launching process, the heat partition decreases with increasing velocity, and when the velocity reaches a very high level, the heat partition tends to a stable value, and most of the heat at the interface is finally transferred into the rail.
姚金明, 傅强. 大电流高速滑动电接触界面热量分配过程[J]. 电工技术学报, 2024, 39(17): 5497-5507.
Yao Jinming, Fu Qiang. Heat Partition Process at Sliding Electrical Contact Interfaces with High-Speed and Large Current. Transactions of China Electrotechnical Society, 2024, 39(17): 5497-5507.
[1] 马伟明, 鲁军勇, 李湘平. 电磁发射超高速一体化弹丸[J]. 国防科技大学学报, 2019, 41(4): 1-10. Ma Weiming, Lu Junyong, Li Xiangping.Electromagnetic launch hypervelocity integrated projectile[J]. Journal of National University of Defense Technology, 2019, 41(4): 1-10. [2] 马伟明, 鲁军勇. 电磁发射技术的研究现状与挑战[J]. 电工技术学报, 2023, 38(15): 3943-3959. Ma Weiming, Lu Junyong.Research progress and challenges of electromagnetic launch technology[J]. Transactions of China Electrotechnical Society, 2023, 38(15): 3943-3959. [3] 胡鑫凯, 鲁军勇, 李白, 等. 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, et al.Thermal damage analysis of insulator in electromagnetic rail launcher under transient conditions[J]. Transactions of China Electrotechnical Society, 2023, 38(21): 5673-5681. [4] Fair H D, Schmidt E E.The science and technology of electric launch: a US perspective[J]. IEEE Transactions on Magnetics, 1999, 35(1): 11-18. [5] 阮景煇, 陈立学, 夏胜国, 等. 电磁轨道炮电流分布特性研究综述[J]. 电工技术学报, 2020, 35(21): 4423-4431. Ruan Jinghui, Chen Lixue, Xia Shengguo, et al.A review of current distribution in electromagnetic railguns[J]. Transactions of China Electrotechnical Society, 2020, 35(21): 4423-4431. [6] 张嘉炜, 鲁军勇, 谭赛, 等. 考虑初始接触压力的滑动电接触界面磁扩散模型[J]. 电工技术学报, 2022, 37(2): 488-495. Zhang Jiawei, Lu Junyong, Tan Sai, et al.A magnetic diffusion model of electromagnetic launcher considering initial contact pressure[J]. Transactions of China Electrotechnical Society, 2022, 37(2): 488-495. [7] Chen Lixue, He Junjia, Xiao Zheng, et al.Experimental study of armature melt wear in solid armature railgun[J]. IEEE Transactions on Plasma Science, 2015, 43(5): 1142-1146. [8] Chen Lixue, Xu Xuan, Wang Zengji, et al.Melting distribution of armature in electromagnetic rail launcher[J]. IEEE Transactions on Plasma Science, 2023, 51(1): 234-242. [9] Yao Jinming, Xia Shengguo, Chen Lixue, et al.Analysis of the melt erosion patterns at rail-armature contact of rail launcher in current range of 10-20 kA/mm[J]. IEEE Transactions on Plasma Science, 2019, 47(3): 1674-1680. [10] 李白, 鲁军勇, 谭赛, 等. 滑动电接触界面粗糙度对电枢熔化特性的影响[J]. 电工技术学报, 2018, 33(7): 1607-1615. Li Bai, Lu Junyong, Tan Sai, et al.Effect of interfacial roughness of sliding electrical contact on the melting characteristics of armature[J]. Transactions of China Electrotechnical Society, 2018, 33(7): 1607-1615. [11] 汤亮亮. 电磁发射中枢轨接触界面金属液化层特性的实验与理论研究[D]. 武汉: 华中科技大学, 2015. Tang Liangliang.Experimental and theoretical study on liquid metal film characteristic of armature/rail contact interface in an electromagnetic launching[D]. Wuhan: Huazhong University of Science and Technology, 2015. [12] Hsieh K T.Numerical study on groove formation of rails for various materials[J]. IEEE Transactions on Magnetics, 2005, 41(1): 380-382. [13] 林庆华, 栗保明. 基于瞬态多物理场求解器的电磁轨道炮发射过程建模与仿真[J]. 兵工学报, 2020, 41(9): 1697-1707. Lin Qinghua, Li Baoming.Modeling and simulation of electromagnetic railgun launching process based on a transient multi-physical field solver[J]. Acta Armamentarii, 2020, 41(9): 1697-1707. [14] 李松乘, 鲁军勇, 程龙, 等. 基于灰色模型的电磁轨道发射装置温度研究[J]. 国防科技大学学报, 2020, 42(5): 90-97. Li Songcheng, Lu Junyong, Cheng Long, et al.Research on temperature of electromagnetic rail launcher based on gray model[J]. Journal of National University of Defense Technology, 2020, 42(5): 90-97. [15] Balić E E.Melt wear control of metals in high-speed sliding contacts[D]. Troy: Rensselaer Polytechnic Institute, 2008. [16] 李白, 鲁军勇, 谭赛, 等. 高速滑动电接触电枢表面动态磨损过程研究[J]. 电工技术学报, 2023, 38(1): 131-139. Li Bai, Lu Junyong, Tan Sai, et al.Research on dynamic wear process of armature surface in high-speed sliding electric contact[J]. Transactions of China Electrotechnical Society, 2023, 38(1): 131-139. [17] Paek-Spidell G Y. Analysis of heat partitioning during sliding contact at high speed and pressure[D]. Wright-Patterson Air Force Base: Air Force Institute of Technology, 2014. [18] Kennedy T C, Plengsaard C, Harder R F.Transient heat partition factor for a sliding railcar wheel[J]. Wear, 2006, 261(7/8): 932-936. [19] Jaeger J C.Moving sources of heat and the temperature at sliding contacts[J]. Journal and Proceedings of the Royal Society of New South Wales, 1943, 76(3): 203-224.