Air flow and differential pressure characteristics in the vacuum tube transportation system based on pressure recycle ducts

Based on the k−ωSST two-equation turbulence model, 2D physical models of the Vacuum Tube Transportation system with pressure recycle ducts were established. Numerical simulation was carried out in the different supersonic state. The air flow characteristics of the VTT with PRD and the influence of the interval length and opening width of PRD on the differential pressure were studied. The results show that the differential pressure is proportional to the square of the train speed and it increases with the increase of the blockage ratio when the system pressure is constant. The existence of PRD can effectively reduce the differential pressure between the train head and tail and it can be reduced by up to 30% when the system pressure is 10 kPa and the blockage ratio is 0.30 and the velocity of train is 1.18Ma. The greater the system blocking ratio is, the more effective the decompression effect of PRD is in VTT. The greater the opening width and the shorter interval length are, the more obviously the influence on the differential pressure in the VTT with PRD. 3E triangle model for evaluating VTT was proposed in this paper, which lays the foundation for the construction of VTT in the future.