Aerodynamic Choked Flow and Shock Wave Phenomena of Subsonic Evacuated Tube Train

doi:10.3901/JME.2021.04.182

Abstract

Abstract: Due to the complex operating environment of evacuated tube trains, it is of great significance to study the aerodynamic phenomena in the tube for the design and optimization of the evacuated tube train. Based on the theory of convergent-divergent intake, the choked flow in the evacuated tube is explained under the subsonic condition. A two-dimensional numerical model of a subsonic evacuated tube train is established with a suspension height, and the phenomena of choked flow in front of the running train in an evacuated tube and shock wave in the rear are studied using the overset meshes technology. The results show that the aerodynamic characteristics of the evacuated tube train can be simulated using the overset meshes technology. The length of the choked flow area in front of the train decreases with the increase of the running speed, and increases with the increase of time. The length of the high pressure area in the tube is linear with the running speed and time. There are expansion wave and shock wave in the rear of the train, and the length of the shock wave increases with the increase of the running speed. Due to the existence of the suspension gap, the shock wave at the rear of the train presents an asymmetry state. The mechanism of the aerodynamic choked flow in front of the train is presented and the asymmetry shock wave phenomena in the rear are obtained using the combination of theory and numerical simulations.

Key words: evacuated tube train, choked flow, shock wave, subsonic train, overset meshes technology

CLC Number:

U171

ZHANG Xiaohan, LI Tian, ZHANG Jiye, ZHANG Weihua. Aerodynamic Choked Flow and Shock Wave Phenomena of Subsonic Evacuated Tube Train[J]. Journal of Mechanical Engineering, 2021, 57(4): 182-190.

References

[1] 沈志云. 关于我国发展真空管道高速交通的思考[J]. 西南交通大学学报,2005,40(2):133-137.SHEN Zhiyun. On developing high-speed evacuated tube transportation in China[J]. Journal of Southwest Jiaotong University,2005,40(2):133-137.
[2] MUSK E. Hypperloop Alpha[R]. SpaceX,2013:13-14.
[3] TAYLOR,CATHERINE L,HYDE D J,et al. Hyperloop commercial feasibility analysis:High level overview[R]. United States Department of Transportation,2016.
[4] 刘加利,张继业,张卫华. 真空管道高速列车气动特性分析[J]. 机械工程学报,2013,49(22):137-143.LIU Jiali,ZHANG Jiye,ZHANG Weihua. Analysis of aerodynamic characteristics of high-speed trains in the evacuated tube[J]. Journal of Mechanical Engineering,2013,49(22):137-143.
[5] 周晓,张殿业,张耀平. 真空管道中阻塞比对列车空气阻力影响的数值研究[J]. 真空科学与技术学报,2008,28(6):535-538.ZHOU Xiao,ZHANG Dianye,ZHANG Yaoping. Numerical simulation of blockage rate and aerodynamic drag of high-Speed train in evacuated tube trans-portation[J]. Chinese Journal of Vacuum Science and Technology,2008,28(6):535-538.
[6] 米百刚,詹浩,朱军. 基于动网格的真空管道高速列车阻力计算方法研究[J]. 真空科学与技术学报,2013,33(9):877-882.MI Baigang,ZHAN Hao,ZHU Jun. Simulation of aerodynamic drag of high-speed train in evacuated tube transportation[J]. Chinese Journal of Vacuum Science and Technology,2013,33(9):877-882.
[7] KIM T,KIM K,KWON H. Aerodynamic characteristics of a tube train[J]. Journal of Wind Engineering and Industrial Aerodynamics,2011,99:1187-1196.
[8] OPGENOORD M M J,CAPLAN P C. Aero-dynamic design of the hyperloop concept[J]. AIAA Journal,2018,56(11):4261-4270.
[9] BRAUN J,SOUSA J,PEKARDAN C. Aerodynamic design and analysis of the hyperloop[J]. AIAA Journal,2017,55(12):4053-4060.
[10] ZHOU Peng,ZHANG Jiye,LI Tian,et al. Numerical study on wave phenomena produced by the super high-speed evacuated tube maglev train[J]. Journal of Wind Engineering & Industrial Aerodynamics,2019,190:61-70.
[11] 周鹏,李田,张继业,等. 真空管道超级列车激波簇结构研究[J]. 机械工程学报,2020,56(2):86-97.ZHOU Peng,LI Tian,ZHANG Jiye,et al. Research on shock wave trains generated by the hyper train in the evacuted tube[J]. Journal of Mechanical Engineering,2020,56(2):86-97.
[12] NIU Jiqiang,SUI Yang,YU Qiujun,et al. Numerical study on the impact of Mach number on the coupling effect of aerodynamic heating and aerodynamic pressure caused by tube train[J]. Journal of Wind Engineering & Industrial Aerodynamics,2019,190:100-111.
[13] 贾文广,董晨光,周艳,等. 基于阻塞比的真空管道交通系统热压耦合研究[J]. 工程热物理学报,2013,34(9):1745-1748.JIA Wenguang,DONG Chenguang,ZHOU Yan,et al. Study of thermal-pressure couple effect in the evacuated tube transportation system on blocking ratio[J]. Journal of Engineering Thermophysics,2013,34(9):1745-1748.
[14] LI Tian,ZHANG Xiaohan,JIANG Yao,et al. Aero-dynamic design of a subsonic evacuated tube train system[J]. Fluid Dynamics & Materials Processing,2020,16(1):121-130.
[15] YANG Yi,ZHANG Huida,HONG Zhaodi. Research on optimal design method for drag reduction of vacuum pipeline vehicle body[J]. International Journal of Computational Fluid Dynamics,2019,33(1-2):77-86.
[16] ZHANG Xiaohan,LI Tian,JIANG Yao. Effect of streamlined nose length on the aerodynamic performance of a 800 km/h evacuated tube train[J]. Fluid Dynamics & Materials Processing,2020,16(1):67-76.
[17] JANZEN R. TransPod ultra-high-speed tube transport-tation:dynamics of vehicles and infrastructure[J]. Procedia Engineering,2017,199:8-17.
[18] 赛义德•法罗基. 飞机推进[M]. 上海:上海交通大学出版社,2011.FAROKHI S. Aircraft propulsion[M]. Shanghai:Shanghai Jiao Tong University Press,2011.
[19] 林建忠,阮晓东,陈邦国,等. 流体力学[M]. 北京:清华大学出版社,2013.LIN Jianzhong,RUAN Xiaodong,CHEN Bangguo,et al. Fluid mechanics[M]. Beijing:Tsinghua University Press,2013.
[20] 理查德•布洛克利,史维. 航空航天科技出版工程:流体动力学与空气热力学[M]. 北京:北京理工大学出版社,2016.BLOCKLEY R,SHYY W. Encyclopedia of aerospace engineering:Fluid dynamics and aer-othermodynamics[M]. Beijing:Beijing Institute of Technology Press,2016.
[21] COOK P H,FIRMIN M C P,MCDONALD M A. Aerofoil RAE2822:Pressure distributions,and boun-dary layer and wake measurements[R]. AGARD Advisory Report No.138,1977.