Maximum gas temperature rise beneath the ceiling in a portals-sealed tunnel fire

Abstract

Sealing tunnel portals is an important approach to control tunnel fires. The maximum gas temperature rise beneath the ceiling was studied under the effects of both fire location and size in a portals-sealed tunnel model. Previous studies showed that the maximum gas temperature rise decreases when fire source is away from the tunnel center, companied with increasing flame inclination angle. In this study, based on dimensional analysis, an empirical model was developed to predict the maximum gas temperature rise beneath the ceiling in a portals-sealed tunnel. It is known that this model can provide reasonably good predictions to different fire scenarios considering fire location and size. A 3/4-power relationship was shown between maximum gas temperature rise and dimensionless fire size, while the normalized maximum gas temperature rise follows an attenuation law of e-φ with the fire location. The focus of the study is more of an academic nature than practical. This is an academic study with pioneering character, which in future may be solved in a more practical way than presented here. However, the outcomes from this study can provide a better understanding for the fire behavior in the portals-sealed tunnel fires and credible prediction about maximum gas temperature under related fire scenarios.