Air distribution in long transportation tunnels of the Baikal-Amur Mainline (BAM)

This paper presents the research findings on air distribution due to piston effect in long railway tunnels. Modeling was performed for a freight train 1 km long in tunnels 3 and 6 km in length by way of numerical experimentation in the ANSYS Fluent environment. As a result, the relations of the air pressure on the front and back surfaces of the train to the train location in the tunnel were obtained, and the aerodynamic drag in the tunnel clearance was evaluated. The results were used to develop a quasi-dynamic model of piston effect for solving problems on static air distribution with network models. The air flow rates calculated for various cross-section tunnels with ANSYS Fluent and a network model exhibited satisfactory agreement. In the meanwhile, the time of solution for a tunnel 3 km long is 4·105 shorter with the network model than with 3D model, which is of practical importance in case of multi-variate calculations in ventilation deign for railway tunnels.