Simulation of aerodynamic drag of high-speed train in evacuated tube transportation

The aerodynamic drag of the high-speed train in the evacuated tube transportation (ETT) was modeled, approximated, and simulated in the dynamic mesh technique. The influence of the ETT conditions, including the pressure, compressibility of air, speed of a train, and blockage ratio, on the drag was analytically studied. In the simulation, the 2-D unsteady Navier-Stokes equations were solved. The simulated results show that the pressure and blockage ratio significantly affect the aerodynamic drag of the training running at high or super speeds in the evacuated tube. For instance, a small blockage ratio and a low pressure results in a weak drag of the train. Moreover, the impact of the tube diameter on the drag is much stron ger at a large blockage ratio than that at a small blockage ratio. As the pressure decreases, the linear dependence of the drag on the blockage ratio weakens, and the drag linearly depends on the square of speed.