Simulation of dynamic electromagnetic characteristics of electromagnetic railgun based on COMSOL moving mesh
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摘要: 精确、快速求解电磁轨道炮电磁特性,对于电磁轨道炮动态特性研究和可靠性设计具有重要意义。基于COMSOL动网格功能,提出一种新的网格划分形式—滑移网格+动网格划分。对电枢区域及枢轨接触的轨道部分进行滑移网格划分,对于其余轨道部分进行动网格划分。这种划分方式不但能解决“静网格”计算准确性低(粗网格)与计算复杂度高(细网格)的问题,也能准确求解瞬态以及快速移动的模型的动态电磁特性。采用脉冲激励电流对所建立的电磁轨道炮模型进行仿真分析。比较了三种静网格与本文提出的网格划分方式的计算时间、计算单元个数。并对不同网格划分方式对于电枢运动速度、电枢中心位置处电流密度分布的仿真结果进行比较,数值计算结果证明了所提出的网格划分方式的有效性与高效性。Abstract: Accurate and fast solution of the electromagnetic characteristics problems is of great significance for the study of dynamic characteristics and reliability design of electromagnetic railguns. Based on the COMSOL moving mesh function, a new form of meshing—slip mesh combined with moving mesh—is proposed. The armature area and the track part where the pivot rail is in contact are meshed in to slip mesh, and the rest of the track part is dynamically meshed. This division method can not only solve the problems of low computational accuracy (coarse mesh) and high computational complexity (fine mesh) of “static mesh”, but also accurately solve the dynamic electromagnetic characteristics problems of transient and fast-moving models. The pulsed excitation current was used to simulate and analyze the established electromagnetic railgun model. The computing time and number of computational units of the three static meshes are compared with the meshing method proposed in this paper. The simulation results of different meshing methods on the armature motion velocity and the current density distribution at the armature center position are compared, and it is proved that the proposed meshing method is effective and efficient.
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随着科学技术的发展,核技术具有零碳排放、能源独立、安全等诸多优势,在人类社会中的地位越来越重要。然而,核辐射事故却为核技术发展迅速蒙上了一层阴影。1986年,苏联切尔诺贝利核电站发生了迄今为止人类历史上最严重的核辐射事故[1]。2011年,日本东北海岸发生了里氏9.0级的强烈地震和海啸,造成了福岛第一核电站的1~3号机组反应堆熔毁[2]。由于反应堆内部高温和高辐射等极端环境,人类无法直接进入进行勘察和处置工作,因此在福岛事故中使用了多种类型和功能的机器人。光纤激光器具有高功率、高光束质量,光束可以远距离柔性传输等优点,可以用于无人区开展激光切割救援等工作[3]。比如Shin等人研究了用10 kW光纤激光器拆除核设施的150 mm厚的厚钢板和大型管道的切割性能[4]。当然,光纤激光器在辐射环境中也会受到影响[5],高能射线会导致增益光纤产生色心等各类缺陷,这些缺陷引起的额外光吸收增加了传输损耗,降低了光纤激光器性能。
课题组基于光纤激光器存在的自漂白效应,利用60CO辐照源探索不同辐照剂量率下的光纤激光器暗化与自漂白的平衡关系。实验先采用低功率光纤振荡器进行不同辐照剂量率下激光器输出功率演化和去辐照后自漂白研究。使用的光纤激光振荡器实验结构如图1所示,谐振腔由常规商业掺镱光纤(YDF)、高反射光纤光栅(HR-FBG)、低反射光纤光栅(OC-FBG)构成,中心波长为976 nm的泵浦源(LDs)通过前向(2+1)×1泵浦信号合束器(FPSC)注入到谐振腔中,激光经过包层光滤除器(CLS)后由光纤端帽(QBH)扩束输出。
首先,利用较高辐照剂量率研究在去辐照后的自漂白效应,结果如图2(a)所示。图2(a)的(I)为未辐照阶段,持续时间为680 s,由于水冷机周期性制冷使得功率计温度周期变化导致测试激光功率也存在周期变化,激光器功率起伏为1.44%;需要注意的是,这个是主要功率测量误差导致,并不是激光器本身功率起伏。图2(a)中(II)为辐照阶段,在总辐照时间298 s内,辐照总剂量为14 900 rad,激光器输出功率从150 W下降至105 W。图2(a)的(III)为去辐照后的自漂白阶段,在光纤激光器的泵浦光子与热效应的共同作用下,激光器输出功率从118 W恢复di至145 W,与初始功率相差仅5 W,表明自漂白效应可以较为有效地恢复由于辐照导致的激光功率下降。
然后,为了探索不同剂量率的自漂白与在线辐照相互作用是否可以达到平衡,开展了不同剂量率的对比研究,结果如图2(b)所示。图2(b)中,总辐照剂量为2 400 rad,红色、蓝色曲线分别对应辐照剂量率为50 rad/s、1 rad/s时激光器归一化输出功率演化情况;在辐照剂量率为50 rad/s时,激光输出功率下降了3%;在辐照剂量率1 rad/s时,功率起伏1.22%,考虑到这里的周期性起伏主要由于水冷机周期性制冷导致,可以认为在低辐照剂量率下,光纤激光器自漂白导致的功率提升与辐照导致的功率下降基本达到平衡。
进一步地,基于图2(b)的实验结果,我们验证了1 kW级光纤激光器中自漂白与辐照平衡的实验现象。在辐照剂量率为0.1 rad/s时,激光器输出激光功率曲线演化如图2(c)所示。从实测功率曲线来看,在总辐照剂量为190 rad的整个辐照过程中,光纤激光器的输出功率都稳定在1 050 W以上,即使考虑前述由于水冷机导致的功率变化,激光器的功率起伏在1.79%以内。如果不考虑水冷机周期性制冷影响,激光器的功率起伏在0.66%以内。
实验首次验证了在一定辐照剂量率下,光纤激光器自漂白效应导致的激光功率提升可以平衡辐照效应导致的功率下降,为相关场景应用的光纤激光器设计提供了有效支撑。后续,我们将继续深入相关研究,探索不同类别、不同结构激光器辐照与自漂白平衡的机理、阈值和可能的应用。
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表 1 电磁轨道炮模型参数
Table 1. Model parameters of electromagnetic railgun
track
length/mmtrack
width/mmtrack
thickness/mmcenter to center
spacing/mmorbital
conductivity/(S·m−1)armature
length/mmarmature
width/mmarmature
conductivity/(S·m−1)900 40 20 50 50 30 表 2 电枢模型参数取值
Table 2. Parameter values of armature model
average height of the rough
surface /μmaverage slope of the
rough surface /μmmicrohardness of
solids /Pacoefficient of
frictionviscous coefficient
of frictionrectangular pulse
current intensity /MA1 0.4 0.11 0.03 0.7 表 3 三种不同静网格划分方式所划分的网格信息
Table 3. Mesh information divided by three different static meshing methods
mesh
informationdomain units
numberboundary elements
numberedge elements
numbermaximum mesh
size/mmminimum mesh
size/mmmesh① 57500 17172 1973 90 16.2 mesh② 935392 79766 4279 18 0.18 mesh③ 326996 55474 5206 90 0.18 mesh④ 372512 53554 4254 90 0.18 表 4 不同网格划分方式与激励电流作用下计算时间
Table 4. Calculation time under different grid partitioning methods and excitation currents
calculation time/s rectangular pulse current Gaussian pulse current mesh① 2491 3907 mesh② 59277 78209 mesh③ 8602 12611 mesh④ 11113 15507 -
[1] 裴畅贵, 刘国志, 金寅翔, 等. 基于COMSOL的电磁发射一体化弹丸动力学分析[J]. 火炮发射与控制学报, 2024, 45(1):104-112Pei Changgui, Liu Guozhi, Jin Yinxiang, et al. Dynamic analysis of electromagnetically launched integrated projectiles based on COMSOL[J]. Journal of Gun Launch & Control, 2024, 45(1): 104-112 [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):3943-3959Ma Weiming, Lu Junyong. Research progress and challenges of electromagnetic launch technology[J]. Transactions of China Electrotechnical Society, 2023, 38(15): 3943-3959 [3] Praneeth S R N, Singh B, Shukl P. A novel iterative technique for interoperability of real-time simulation and finite element simulation using railgun circuit[J]. IEEE Transactions on Circuits and Systems II: Express Briefs, 2022, 69(8): 3575-3579. [4] Zhang Huihui, Li Shuai, Gao Xiang, et al. Distribution characteristics of electromagnetic field and temperature field of different caliber electromagnetic railguns[J]. IEEE Transactions on Plasma Science, 2020, 48(12): 4342-4349. doi: 10.1109/TPS.2020.3034121 [5] Zhou Pengfei, Li Baoming. Numerical calculation of magnetic-thermal coupling and optimization analysis for velocity skin effect[J]. IEEE Transactions on Plasma Science, 2021, 49(12): 3994-4001. doi: 10.1109/TPS.2021.3123821 [6] Tosun N, Ceylan D, Polat H, et al. A comparison of velocity skin effect modeling with 2-D transient and 3-D quasi-transient finite element methods[J]. IEEE Transactions on Plasma Science, 2021, 49(4): 1500-1507. doi: 10.1109/TPS.2021.3067105 [7] Yang K S, Kim S H, Lee B, et al. Electromagnetic launch experiments using a 4.8-MJ pulsed power supply[J]. IEEE Transactions on Plasma Science, 2015, 43(5): 1358-1361. doi: 10.1109/TPS.2015.2394805 [8] 杨艺, 郭静. 美军电磁轨道炮发展综述[J]. 国外坦克, 2015(4):35-38Yang Yi, Guo Jing. Overview of the development of US electromagnetic rail guns[J]. Foreign Tanks, 2015(4): 35-38 [9] 温艳玲, 戴玲, 祝琦, 等. 分布储能式电磁轨道炮效率分析[J]. 强激光与粒子束, 2020, 32:025007 doi: 10.11884/HPLPB202032.190332Wen Yanling, Dai Ling, Zhu Qi, et al. Efficiency of distributed energy storage electromagnetic railgun[J]. High Power Laser and Particle Beams, 2020, 32: 025007 doi: 10.11884/HPLPB202032.190332 [10] 郭仁荃, 李豪杰, 杨宇鑫. 基于COMSOL的轨道炮弹引信部位磁场组合屏蔽仿真[J]. 探测与控制学报, 2020, 42(3):8-13,19Guo Renquan, Li Haojie, Yang Yuxin. COMSOL simulation of railgun projectile fuze combination magnetic shielding[J]. Journal of Detection & Control, 2020, 42(3): 8-13,19 [11] 金亮, 巩德鑫. 电磁轨道炮电枢电磁推力特性分析与验证[J]. 火炮发射与控制学报, 2023, 44(6):1-7,27Jin Liang, Gong Dexin. Analysis and verification of armature electromagnetic thrust characteristics of an electromagnetic railgun[J]. Journal of Gun Launch & Control, 2023, 44(6): 1-7,27 [12] 关晓存, 李治源, 赵然, 等. 线圈炮电枢电磁-热耦合仿真分析[J]. 强激光与粒子束, 2011, 23(8):2267-2272 doi: 10.3788/HPLPB20112308.2267Guan Xiaocun, Li Zhiyuan, Zhao Ran, et al. Simulation analysis of electromagnetic-thermal coupling for armature in inductive coilgun[J]. High Power Laser and Particle Beams, 2011, 23(8): 2267-2272 doi: 10.3788/HPLPB20112308.2267 [13] 王昊. 电磁轨道温度时空分布特性研究[D]. 天津大学, 2020: 21-27Wang Hao. Study on space-time distribution characteristics of rail electromagnetic launch[D]. Tianjin: Tianjin University, 2020: 21-27 [14] 楼宇涛, 栗保明. 管身对中口径电磁轨道炮的影响分析[J]. 强激光与粒子束, 2015, 27:093201 doi: 10.11884/HPLPB201527.093201Lou Yutao, Li Baoming. Influence of containment for medium caliber electromagnetic railgun[J]. High Power Laser and Particle Beams, 2015, 27: 093201 doi: 10.11884/HPLPB201527.093201 [15] 马硕, 杨帆, 农奥兵, 等. 影响电磁炮轨道电流密度和温度的主要因素分析[J]. 兵器材料科学与工程, 2022, 45(2):1-9Ma Shuo, Yang Fan, Nong Aobing, et al. Analysis of main factors affecting the rail current density and temperature of electromagnetic railgun[J]. Ordnance Material Science and Engineering, 2022, 45(2): 1-9 [16] 关永超, 邹文康, 何勇, 等. 串联型双轨增强电磁轨道炮电路模拟[J]. 强激光与粒子束, 2014, 26:115001 doi: 10.11884/HPLPB201426.115001Guan Yongchao, Zou Wenkang, He Yong, et al. Circuit simulation of the electromagnetic railgun system[J]. High Power Laser and Particle Beams, 2014, 26: 115001 doi: 10.11884/HPLPB201426.115001 [17] 葛一凡, 秦实宏, 陈彪, 等. 电磁发射轨道截面瞬态电磁热的耦合场分析[J]. 武汉工程大学学报, 2022, 44(3):331-335Ge Yifan, Qin Shihong, Chen Biao, et al. Transient electromagnetic thermal coupling field of electromagnetic launch rail section[J]. Journal of Wuhan Institute of Technology, 2022, 44(3): 331-335 -