Research On Heat Transfer Simulation Of Low Vacuum Tube Maglev Train Based On Fluid-solid Coupling

In order to break through the speed limit of the train in the open atmospheric environment,the low vacuum tube maglev train is given great expectation.Although this concept can achieve higher train speed in theory,it also brings new problems such as piston effect and heat dissipation.Although the study about the low vacuum tube maglev train has been in progress,most of the achievements focus on the study about flow field,pressure field and aerodynamic heating in the tube,and the study about heat transfer between heat source in the tube is relatively less.These heat transfer problems will directly affect the train operation safety.In this paper,the study is based on Fluid-Solid coupling,the heat transfer of the low vacuum tube maglev train in the tube is regarded as research object.The threedimensional numerical calculation model of the low vacuum tube maglev train is established on the conditions of three-dimensional and compressible by using Fluent.The temperature field of the low vacuum tube maglev train is studied under the conditions of different blockage ratios(0.15,0.2,0.25,0.3,0.35,0.4),different vacuum degrees(0.01 atm ～ 1atm)and different train speeds(400 ～ 1000km/h)during steady-state operation.This paper analyzes the surface temperature rise of maglev train when it runs at high speed in low vacuum tube and the changes law of surface temperature rise of main heat source under the influence of blockage ratio,vacuum degree and train speed.The temperature field of the low vacuum tube maglev train is studied when blockage ratio is0.3,vacuum degree is 0.01 atm or 0.1atm,and train speed is 600km/h,800km/h or1000km/h during 10 minutes interval-state operation and braking-state operation,and the temperature rise of train surface is deeply investigated.The simulation results show that when the train speed and the blockage ratio are constants,the temperature of train surface increases with the vacuum degree.The temperature of the train surface decreases gradually with the increasing blockage ratio when the vacuum degree is high or the vacuum degree is low but the train speed is low.When the vacuum degree is low but the train speed is high,the temperature of the train surface increases with the blockage ratio.When the blockage ratio is constant,the temperature of the train surface decreases gradually with the increasing train speed in the case of the high vacuum degree;the temperature of the train surface increases gradually with the train speed in the case of the low vacuum degree.Under several steady-state simulation conditions of 600km/h or more,the highest train surface temperature is630.8766 K,when vacuum degree is 0.01 atm,train speed is 600km/h and blockage ratio is 0.15.If there are no additional cooling measures,the surface temperature of heatproducing equipment in the tube increases in the form of proportional function with the number of trains departing under the condition of train operation and braking.The main innovations of this paper are as follows: In this paper,the heat transfer of low vacuum tube maglev train is simulated and analyzed by comprehensively considering the heating of equipment on the train,the heating of track,the aerodynamic heating and the blocking effect,and the laws of temperature rise variation in the tube are obtained.In this paper,the temperature rise law of low vacuum tube maglev train in the process of interval-state operation and braking-state operation is studied,and the laws of the temperature rise variation in the tube during the interval-state operation and braking-state operation process are obtained.It provides a reference for the heat transfer theoretical research,design,manufacture and engineering construction of low vacuum tube maglev train.