Experimental Investigation on Temperature Profiles at Ceiling and Door of Subway Carriage Fire

Previous studies usually used the common tunnel model and paid little attention to the propagation characteristics of fire in the carriage structure with multiple lateral openings. In the current study, experiments were carried out in a reduced-scale (1:5) subway carriage model to study the propagation characteristics of carriage fire. The main focuses were on the temperature contour profiles and distribution laws under the ceiling and at different doors inside the carriage. Results show that although the status of the side door of the carriage does not have a significant effect on the mass loss rate of fuel combustion, the temperature distribution under the ceiling will be affected under the effect of the smoke overflow of the door opening. The effect of door status on the longitudinal ceiling temperature is mainly on the area between the fire source and the adjacent door. For the transverse ceiling temperature above the fire source, the effect of the status of the door is significant with the increase of the fire source. Besides, the temperature contour profile at the door shows regular distribution. In the process of gradually increasing the temperature as the height increases, the isotherm gradually changes from a horizontal straight line to two inverted triangular sides, the temperature at the door has been basically in the ambient temperature from the dimensionless height (normalized by the height of the door) below 0.6. The measured radiation at the upper part of the carriage end is about 5 times higher than that in the middle of the door adjacent to the fire source, and the ratio is not significantly affected by the heat release rate. The results of this study can be of use to the fire-protection community to better understand fire dynamics.