Aerodynamic forces and moments on high-speed trains passing by each other

The aerodynamic forces and moments on two high-speed trains passing by in opposite directions have been calculated to examine their effect on the running safety of the trains. Three dimensional unsteady Navier-Stokes equation has been employed to obtain the unsteady-state flow solution around the EMU-320 trains passing by each other in the open air as well as in the tunnel. The pressure-ward rolling moment has been introduced as a method to assess the running safety of the trains. The results show that the maximum repulsive rolling moment was observed at the 1st vehicle, while the maximum attractive rolling moment was observed at the last vehicle. By comparing the maximum rolling moment according to various track conditions and train speeds, it was found that the maximum repulsive moment in tunnel was the most threatening force. Additionally, the pressure-ward rolling moment increased with higher train speed, narrower track spacing, and smaller tunnel cross-sectional area. As a result of applying quasi-static three mass model method, it was confirmed that the maximum pressure-ward rolling moment was amounted up to 40 % of the sustaining rolling moment of the EMU-320 train when driving at 400 km/h in the tunnel of Honam High-Speed Railway.