The Effect of Subway Tunnel Section Shape on the Moving Train Fire Smoke Flow Characteristics

Abstract

Based on dynamic grid technology, established a full-size model of subway train and the tunnel, the influence of tunnel section shape (circle, rectangle and arch) on fire smoke flow characteristics during the braking and stop process of subway in tunnel after the fire broke out under the bottom of the vehicle while moving is simulated. The computational results show follows: The results show that the shape of the tunnel has a great influence on the flow velocity around the train under the piston wind and smoke characteristics. The range of high temperature smoke in the arch tunnel fire center upstream is smallest at stop instant. The lower bottom space of the rectangular section tunnel is not conducive to the initial high temperature smoke diffusion and even accelerates the combustion of the train. The narrow side waist of the rectangular section tunnel causes the smoke quickly encircling the train body and the piston wind would slow down faster, which will accelerate the smoke deposition, and is not conducive to the smoke flow downstream. The narrow upper space of the arch section tunnel is favorable for the smoke flow downstream, but the smoke flow back early at about 180s. At 360s, the total temperature and concentration of the arch section tunnel is the lowest, and the rectangle is the highest.