Influence of tunnel slope on the one-dimensional spread of smoke transportation and temperature distribution in tunnel fires
Zihe Gao, Mingge Liu, Pengju Zhao, Changbin Yan
Abstract
As a widely used fundamental transportation facility, tunnels always have a specific longitudinal slope, which may significantly affect smoke transportation, but the knowledge of smoke transportation in the sloped tunnel is relatively insufficient. In this work, a series of numerical simulations are performed to explore the influence of longitudinal slope on smoke transportation and temperature distribution in tunnels. The heat release rate ranges from 3 MW to 10 MW, and the tunnel slope varies from 0 % (horizontal tunnel) to 8 %. The outcomes of this work reveal that as tunnel slope and heat release rate rise, due to the growth of the induced air inflow velocity at the lower tunnel entrance, the fire plume and the high-temperature combustion region incline downstream of the tunnel. Consequently, the ceiling smoke needs to propagate a farther distance for approaching the one-dimensional spread stage. Moreover, a correlation to predict the smoke ceiling temperature distribution along the tunnel longitudinal direction is established by selecting the one-dimensional spread stage starting position as the reference point. Finally, for validating the applicability and reliability of the predictive equation, it is compared with the outcomes of previous small-scale and full-scale studies in horizontal and sloped tunnels.