Dynamic Characteristics of Metal Liquid Film at Armature-Rail Interface in High-Speed Sliding Electrical Contact
Lou Jianyong1, Feng Yigong1, Liu Qian1, Yan Jianghan1, Qie Jiahui2
1. School of Electrical Engineering Xi'an Jiaotong University Xi'an 710049 China; 2. Baoding Power Supply Subsidiary Company State Grid Hebei Electric Power Supply Co. Ltd Baoding 071000 China
Abstract：In the context of electromagnetic launch, a prototypical high-speed sliding electrical contact process, the dynamic characteristics of the metal liquid film at the armature-rail interface play a decisive role in ensuring electrical contact stability and energy transfer efficiency. Aiming to investigate the regulatory mechanisms governing liquid film behavior under high-speed conditions, this study constructs a comprehensive hydrodynamic lubrication model that integrates roughness correction and viscosity-pressure coupling and systematically analyzes the impacts of rail surface roughness, roughness distribution patterns, and armature velocity on the armature surface melting rate, liquid film pressure distribution, and film thickness evolution. The results reveal that the surface roughness of the rail is the dominant factor regulating the melting rate of the armature and the distribution of the liquid film thickness. As the roughness increases, the melting rate on the armature surface significantly rises, while the time to reach a fully lubricated state is correspondingly delayed. When the roughness exceeds a critical threshold, the proportion of the distance over which energy is more efficiently converted into armature kinetic energy under full lubrication significantly decreases, thereby reducing the overall energy conversion efficiency of the launching system. In contrast, the pattern of roughness distribution has a relatively minor effect on the melting rate under high-speed conditions. However, the texture orientation notably modulates the liquid film pressure distribution by altering the shear flow path within the liquid film. The liquid film pressure distribution exhibits pronounced edge effects, with peak values primarily concentrated near the inner region close to the armature head. As the armature velocity increases, the pressure peak demonstrates a non-monotonic trend characterized by an initial increase followed by a decrease. At low speeds and pressures, the viscosity-pressure coupling effect causes only limited viscosity increases due to weak intermolecular interactions within the liquid film. As a result, its impact on flow resistance and melting rate is negligible. As velocity increases, an exponential rise in liquid film pressure triggers the viscosity-pressure coupling mechanism of the Roelands model, causing nonlinear growth in the viscosity of liquid metal. This leads to significant shear heating within the film, while the high-viscosity state reduces its thermal conductivity, thereby accelerating the melting of the armature surface. Analysis indicates that neglecting the viscosity-pressure coupling effect under high-speed launch conditions leads to an underestimation of the metal liquid film's viscosity, which can result in inaccurate predictions of the liquid film's dynamic behavior. To ensure model fidelity and proper design, we recommend integrating a dynamic viscosity correction mechanism based on viscosity-pressure coupling in engineering applications of electromagnetic launch systems. This study deepens the understanding of metal liquid film dynamics in high-speed sliding electrical contacts through a multi-scale coupling analysis. However, further investigation is needed into the temperature dependence of the viscosity-pressure coefficient, the non-Newtonian behavior of liquid metals under extreme shear, and the long-term impact of rail surface evolution on film stability across repeated launches. These challenges necessitate combined approaches involving high-speed dynamic microscopy, in-situ material characterization, and molecular dynamics simulations.
娄建勇, 冯一工, 刘谦, 闫江涵, 郄家辉. 高速滑动电接触枢轨界面金属液膜的动态特性[J]. 电工技术学报, 2026, 41(11): 3589-3601.
Lou Jianyong, Feng Yigong, Liu Qian, Yan Jianghan, Qie Jiahui. Dynamic Characteristics of Metal Liquid Film at Armature-Rail Interface in High-Speed Sliding Electrical Contact. Transactions of China Electrotechnical Society, 2026, 41(11): 3589-3601.
[1] 马伟明. 关于电工学科前沿技术发展的若干思考[J]. 电工技术学报, 2021, 36(22): 4627-4636. Ma Weiming.Thoughts on the development of frontier technology in electrical engineering[J]. Transactions of China Electrotechnical Society, 2021, 36(22): 4627-4636. [2] 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. [3] 翟小飞, 李鑫航, 刘华, 等. 电磁轨道发射系统电路模型及发射效率研究[J]. 电工技术学报, 2023, 38(11): 2841-2849, 2860. Zhai Xiaofei, Li Xinhang, Liu Hua, et al.Research on circuit model and launch efficiency of electromagnetic rail launch system[J]. Transactions of China Electro-technical Society, 2023, 38(11): 2841-2849, 2860. [4] 邢泽西, 王健, 李鸿剑, 等. 重复发射下铝沉积层对枢轨界面滑动电接触的影响[J]. 电工技术学报, 2025, 40(10): 3044-3055. Xing Zexi, Wang Jian, Li Hongjian, et al.Influence of aluminum deposition layers on sliding electrical contact at the pivot-rail interface under repetitive emission[J]. Transactions of China Electrotechnical Society, 2025, 40(10): 3044-3055. [5] 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. [6] Flegontova E Y, Yuferev V S.Influence of lubricant on the motion of a body in an electromagnetic railgun accelerator. II. Hydrodynamics of a conducting lubricant[J]. Technical Physics, 1999, 44(10): 1226-1233. [7] Ghassemi M, Barsi Y M.Effect of liquid film (indium) on thermal and electromagnetic distribution of an electromagnetic launcher with new armature[C]//2004 12th Symposium on Electromagnetic Launch Technology, Snowbird, UT, USA, 2004: 386-392. [8] Wang Lei.Modeling of the armature-rail interface in an electromagnetic launcher with lubricant injection [D]. Atlanta: Georgia Institute of Technology, 2008. [9] Hsieh P Y M. Liquid metal boundary lubrication of sliding electrical contacts[D]. Evanston: Northwestern University, 2008. [10] Singer I L, Veracka M J, Boyer C N, et al.Wear behavior of lubricant-conditioned copper rails and armatures in a railgun[J]. IEEE Transactions on Plasma Science, 2011, 39(1): 138-143. [11] Zhang Bao, Jin Ke, Kou Yong, et al.Modelling of magneto-electro-thermo-mechanical coupled behavior of the lubricating liquid film for the electromagnetic launch[J]. International Journal of Heat and Mass Transfer, 2022, 196: 123267. [12] Liao Guiwen, Wang Wei, Wang Bin, et al.Transient mixed-lubrication and contact behavior analysis of metal liquid film under magneto-thermal effect[J]. International Journal of Mechanical Sciences, 2024, 271: 109142. [13] Hamrock B J, Schmid S R, Jacobson B O.Fundamentals of Fluid Film Lubrication[M]. 2nd ed. Boca Raton: CRC Press, 2004. [14] 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. [15] Patir N, Cheng H S.Application of average flow model to lubrication between rough sliding surfaces[J]. Journal of Lubrication Technology, 1979, 101(2): 220-229. [16] Peng Xiaoting, Zhan Zaiji, Li Zhixin.Experimental study of railgun aluminum armature electrical contact ablation[J]. International Journal of Applied Electro-magnetics and Mechanics, 2014, 46(3): 511-518. [17] 温诗铸, 黄平. 摩擦学原理[M]. 3版. 北京: 清华大学出版社, 2008. [18] 娄建勇, 徐顺, 高源, 等. 电磁发射前期电枢表面熔蚀特性[J]. 电工技术学报, 2025, 40(14): 4668-4676. Lou Jianyong, Xu Shun, Gao Yuan, et al.The erosion characteristics of armature surface in the early stages of electromagnetic launch[J]. Transactions of China Electrotechnical Society, 2025, 40(14): 4668-4676. [19] 祝丽花, 刘平, 谷雨茜, 等. 高速电磁能推进装置枢轨接触特性分析及实验研究[J]. 西安交通大学学报, 2025, 59(1): 28-36. Zhu Lihua, Liu Ping, Gu Yuxi, et al.Analysis and experimental research on the armature-rail contact characteristics of high-speed electromagnetic propulsion devices[J]. Journal of Xi’an Jiaotong University, 2025, 59(1): 28-36. [20] 肖铮. 电枢—轨道载流滑动接触面摩擦磨损研究[D]. 武汉: 华中科技大学, 2012. Xiao Zheng.Friction and wear behavior of armature-rail sliding electrical contact surface[D]. Wuhan: Huazhong University of Science and Technology, 2012. [21] 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. [22] 铁摩辛柯(Timoshenko S)(苏), 古地尔(Goodier J N). 弹性理论[M]. 徐芝纶, 译. 北京: 高等教育出版社, 1990. [23] Han S M, Benaroya H, Wei T.Dynamics of transversely vibrating beams using four engineering theories[J]. Journal of Sound and Vibration, 1999, 225(5): 935-988. [24] 宋志安, 于涛, 李红艳, 等. 机械结构有限元分析: ANSYS与ANSYS Workbench工程应用[M]. 北京: 国防工业出版社, 2010. [25] 王向东, 邓爱民. 材料力学[M]. 北京: 中国水利水电出版社, 2014. [26] 刘旭堃, 于歆杰, 刘秀成, 等. 电磁轨道炮运行阶段系统发射效率和电枢出膛动能研究[J]. 电工技术学报, 2017, 32(3): 210-217. Liu Xukun, Yu Xinjie, Liu Xiucheng, et al.Researches on the system launch efficiency and the armature muzzle kinetic energy of a constructed electro-magnetic railgun[J]. Transactions of China Electro-technical Society, 2017, 32(3): 210-217. [27] 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. [28] Kothmann R E, Stefani F.A thermal hydraulic model of melt-lubrication in railgun armatures[J]. IEEE Transactions on Magnetics, 2001, 37(1): 86-91. [29] 冯登. 电枢轨道高速滑动电接触界面热流体动力润滑研究[D]. 武汉: 华中科技大学, 2014. Feng Deng.Thermohydrodynamic lubrication research of armature-rail high speed sliding electrical contact interface[D]. Wuhan: Huazhong University of Science and Technology, 2014. [30] Houpert L.New results of traction force calculations in elastohydrodynamic contacts[J]. Journal of Tribology, 1985, 107(2): 241-245. [31] Pelofsky A H.Surface tension-viscosity relation for liquids[J]. Journal of Chemical & Engineering Data, 1966, 11(3): 394-397.
2026, Vol. 41 
