Study on the smoke movement and downstream temperature distribution in a sloping tunnel with one closed portal

In this paper, downstream temperature distribution and smoke movement were investigated in a slopping tunnel with one ended-portal, experimentally and numerically. A series of experimental and simulation tests were conducted in a 1:10 small scale model tunnel. According to the results, two typical behaviors of smoke movement were found out: 1) the fire plume tended to incline towards the end wall in the tunnel with or without slope when the fire was located near the end wall. Moreover, for the tunnel with slope, the inclination was more severe as slope became larger. 2) when the fire occurs in an inclined tunnel, the interface of smoke layer downstream the fire is parallel to the horizontal level. During the smoke propagation, a clear stratification could be observed. Results also indicated that the dispersion of smoke would be more confined when the tunnel slope increased. By conducting a series of simulation cases, we carried out an empirical model to predict the downstream temperature distribution beneath tunnel ceiling, taking into consideration the sealing condition, tunnel slope and heat release rate. The prediction model revealed that the downstream maximum temperature decreased as the distance to fire source increased. Meanwhile, it followed an exponential decrease to 0.694 power of heat release rate and subjected to an exponential decrease when the tunnel slope increased.