Aerodynamic Effects Produced by a High-Speed Train Traveling through a Tunnel Considering Different Car Numbers

• Published in: Symmetry (Basel) 2022-03, Vol.14 (3), p.479
• Main Authors: Du, Jian-Ming, Fang, Qian, Wang, Gan, Wang, Jun, Li, Jian-Ye
• Format: Article
• Language: English
• Subjects: aerodynamic pressure; car number; Field study; High speed rail; high-speed train; micropressure wave; Railroad cars; railway tunnel; Reynolds number; Simulation; Trains; Tunnel linings; Turbulence models
• ISSN: 2073-8994; 2073-8994
• DOI: 10.3390/sym14030479

The geometrical configurations of high-speed trains and tunnels are symmetric. However, the aerodynamic pressure acting on tunnel walls induced by high-speed trains passing through is unsymmetric. The study of the aerodynamic effects produced by high-speed trains traveling through tunnels can be treated as the theoretical basis for safety evaluations of tunnel structures and operational trains. There is still no consensus regarding the use of three or four cars, as opposed to eight, in evaluations aerodynamic effects. To solve this problem, three-dimensional simulations were conducted to evaluate the effects of car number on the aerodynamic pressures of the tunnel lining and micropressure waves due to tunnel portals. The input parameters of our simulation were verified by comparing with field monitoring data obtained by other researchers. The results indicate that the root cause of the differences in the aerodynamic pressures of the tunnel lining and the micropressure waves of tunnel portals according to car number is that the wave diagrams of different car numbers inside tunnels present significant differences. The differences in the maximum positive and negative pressure peaks experienced by the tunnel lining between a three- and an eight-car model are 11.70% and 44.0%, respectively, while the differences in the same scenario are as high as 48.6% and 46.4% after train tail leaves the tunnel. When the car number increases from three to eight, the time to reach the maximum negative pressure peak of the micropressure wave is periodically delayed. The delay period can be defined as T = loc/v (loc: single train carriage length, v: train speed).