Numerical analysis for aerodynamics of high-speed trains passing tunnels

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Numerical analysis for aerodynamics of high-speed trains passing tunnels

Zhao, Jing / Li, Renxian

High-speed trains running at 200~350km/h will be operated on Chinese high-speed railways after 2010. Some of the high-speed railways in China will be built in mountainous areas. Many tunnels have to be constructed for the railways. However, the tunnel aerodynamic effect of high-speed trains is not very clear, especially the aerodynamic influence when the train is running in or out of tunnels. Examples are the effect of air pressure impulse on the train window strength and on the ear films of passengers, the relationship between the tunnel section size and the aerodynamic force acted on the train body, the relationship between the buffer structure of the tunnel entrance and the intensity of air pressure impulse, and so on. Based on Reynolds average Navier-Stokes equations of viscous incompressible fluid, and on two equation turbulent models, the aerodynamic effect of high-speed train in tunnels was investigated by means of the technology of moving grids in computational fluid dynamics method. Flow fields of high-speed train for 4 running speeds (200, 250, 300, 350km/h), 3 sizes of tunnel sections and 2 kinds of buffer structures for tunnel entrance were calculated. The results show that the aerodynamic effect of the tunnel's blockage ratio is larger than that of train's speed when the tunnel section size is smaller than a finite blockage ratio; the buffer structure for a tunnel entrance may reduce the aerodynamic influence effectively. Based on the simulation results of the investigation, some suggestion values between tunnel blocking ratio and train running speed were presented.