Abstract: In order to study the aerodynamic characteristics of high-speed trains in the evacuated tube in the low-pressure environment, the fluid model, mathematical model and numerical model of aerodynamic computation of high-speed trains in the evacuated tube in the low-pressure environment are established. The effect of internal tube pressure(1.01×103-1.01×104 Pa), blockage ratio (0.2-0.7) and train speed (600-1 000 km/h) on the drag coefficient, aerodynamic drag force and aerothermal effect are studied. The computational results show that in the lower-pressure(1.01×103-1.01×104 Pa) environment, the air flow in the evacuated tube can be described by continuum model. The flow field of high-speed trains in the evacuated tube can be described by 3D compressible Navier-Stokes equation. The friction drag coefficient of high-speed trains is far smaller than the pressure drag coefficient. The pressure drag coefficient and aerodynamic drag coefficient is basically nothing to do with the internal tube pressure and train speed, but mainly depends on the blockage ratio. The aerodynamic drag force of high-speed trains is almost linear with the tube pressure, and almost square with the train speed, and also increases with the increase of blockage ratio. The maximum temperature on the surface of high-speed trains is essentially independent of the internal tube pressure, and mainly depends on the train speed and blockage ratio.

Key words: Aerodynamic drag force, Blockage ratio, Evacuated tube, High-speed train, Internal tube pressure