Aerodynamic Behavior And Influence Parameter Identification Of Transonic Maglev Train In Evacuated Tube Train

Evacuated tube transportation is one of the important development directions of green,energy-saving and high-speed transportation technology in the future.The pneumatic environment in the tube is an important factor to ensure the safe operation of vehicles.Based on shear stress transfer(SST)k-ω,the aerodynamic characteristics of evacuated tube maglev transportation system in transonic stage are simulated by turbulence model method,the numerical simulation method is verified,and the grid independence is analyzed.This thesis introduces the method of orthogonal experimental design into the flow field analysis of evacuated tube train,and identifies the sensitivity and interaction of key characteristic parameters when the train is running in the tube.Based on the traditional aerodynamic analysis,the channel and gap are added in the tube train,and its aerodynamic characteristics,gas flow and heat transfer in the tube during the complete transonic operation cycle are analyzed and evaluated.The results show that the blockage ratio has the greatest influence on the flow field distribution in front of and in the wake of the train,and the vehicle speed is the most key characteristic parameter affecting the gas flow and heat transfer characteristics behind the train.The air pressure in the tube mainly affects the air wake behind the rear of the train.The aerodynamic phenomena such as congestion and expansion wave become more significant with the increase of speed and blockage ratio,which must be considered in the design of tube train.The aerodynamic resistance will increase with the increase of the three,among which the resistance is approximately linear with the velocity,which is significantly different from the open atmospheric environment.The maximum temperature in the tube will decrease with the increase of air pressure.The minimum temperature decreases with the increase of velocity,blockage ratio and air pressure in the tube.After introducing the channel and gap,it is found that the influence of the use of the channel on the train pressure resistance is mainly significant at the end of the deceleration stage.The friction resistance increases with the addition of axial channel in the acceleration and deceleration stages,and decreases with the addition of axial channel in the deceleration process.The flow field around the rear of the train will be more affected by the axial channel.In different operation stages,the influence of radial clearance on the flow field in radial clearance is different,especially the pressure field.The addition of radial clearance is not conducive to improve the surrounding flow field,especially in the deceleration process.In addition,it is found that the aerodynamic shape design of the channel outlet is very important,and the train speed must be considered.Based on the analysis of convection field environment and aerodynamic behavior,this paper systematically studies the sensitivity of key characteristic parameters of evacuated tube train and its influence on the flow and aerodynamic heating characteristics in the tube,and reveals the unsteady aerodynamic characteristics of tube train in transonic stage.The research results will provide guidance for the aerodynamic shape optimization design of evacuated tube train and the reasonable matching of key characteristic parameters.