The Influence Of Blockage Ratio On Aerodynamic Heating And Heat Transfer Of The Evacuated Tube Transportation System

With the improvement of train’s velocity, the rubbing effect is more and more seriously between the train and the air. In the normal atmosphere, the proportion of air resistance is80%in the total resistance when the train’s velocity is bigger than400km/h. This is considered uneconomical, and this problem also blocks the improvement of train’s velocity at the same time. As a result, The Evacuated Tube Transportation (ETT) system is raised. Although the study about ETT has been in progress, the achievement by this time is only limited to the study about pressure field, and it doesn’t relate to the study about aerodynamic heating. The aerodynamic heating is no only effect the high speed and high efficiency working of the ETT system, but also relates to its safe working.In this paper, the aerodynamic heating and heat transfer in the ETT is regarded as research subject. Using Ansys workbench13.0, based on viscous fluid Navier-Stokes equation and k-ε turbulence model, for the first time establish three-dimensional physical model and mathematical model of the Evacuated Tube Transportation system on the conditions of three-dimensional and compressible. The ETT is numerical simulated for different blockage ratios on the conditions of steady and transient with one hour.The thermodynamic effect of high-speed train in evacuated tube is studied in three aspects. Firstly, there are two different pressure in the tube:0.1atm、0.5atm. Secondly, the train has two different velocities:150m/s>200m/s. Thirdly, the blockage ratios are four:0.18、0.23、0.32、0.46. The simulation results show that:when the speed of the train and the pressure of the system are constants, in the pressure field, the stagnation pressure is gradually increased with the increase of the blockage ratios, but the growth is getting slower; Vortex region pressure reduces gradually, and has accelerated the decreasing trend; as a result, the differential pressure between the head and the end of the train is linear increment. In the temperature field, the aerodynamic heating is getting more as the blockage ratios increases, and its trend is ascending parabolic with amplification gradually increasing growth. The aerodynamic heating is growing as ascending parabolic with amplification gradually decreasing growth with the time. When the time is short, the aerodynamic heating grows rapidly, and with the time longer, the trend become gently and up to a value.