Study On Aerodynamic Characteristics Of Evacuated Tube Transport-high Temperature Superconducting Maglev

Incorporating both evacuated tube transport(ETT)concept and high temperature superconducting maglev(HTS Maglev)technology,evacuated tube transport-high temperature superconducting maglev(ETT—HTS maglev)system as an innovative transportation preponderats in low resistance,low noise,no friction and stable suspension.The ETT-HTS maglev system is likely to be high speed even ultra-high speed traffic ground,regarded as "the fifth transpotation for human" in future.The first ETT—HTS Maglev test platform "Super-Maglev" successfully developed at Southwest Jiaotong University in Chengdu,China in 2014,which receives much attention in the wide world and provides powerful hardware support for following experimental study.Utilizing this platform the fundamental characteristic of HTS maglev vehicle running at a low pressure environment would be investigated,such as aerodynamic characteristics,dynamic characteristics and magnetic properties.Limited to fund,technology and site,many researchers only simulated and analyzed aerodynamic characteristics of ETT-HTS maglev system,but there are fewer related experiments.Therefore,refering to previous studies in numerical simulation,the article firstly establishs the two-dimensional ETT-HTS Maglev numerical model by computational fluid dynamics(CFD)softwork.The aerodynamic drag of HTS maglev vehicle in tube with different pressures,blockage ratio and speed is simulated and compared with that in open.Combined with the mechanism of airflow influence,this paper proffers theoretical explanations of the changes in aerodynamic characteristics on the vehicle surface caused by above three factors.However,the real flow field is hard to simulated by numerical CFD softwork,and it is necessary to carry out experimental researches about flow characteristics of ETT-HTS maglev system in the "Super-Maglev" platform.This paper tests and records average speeds of the HTS maglev vehicle in inertial motion without the driving force,then focus on computing and analyzing air drag,to demonstrate that the air resistance is reducted clearly in low pressure environment.Further improving aerodynamic performance of the HTS maglev vehicle in evacuated tube,The paper finally investigates aerodynamic characteristics from two aspects in car body shap and pipe structure.The results of experiments and simulations demonstrate that both of car body shap and pipe structure impact aerodynamic performance,and the blockage ratio has larger influence on aerodynamic drag.Momeover,as air drag is relieved effectively by airshafts in experiment and simulation,the paper gives the suggestion that the reasonable design of airshafts should be recommended in the HTS Maglev-ETT application to improve stability and energy conservation.