Experimental Study on Flame Length of Sidewall Fire with Different Aspect Ratios and Orientations in an Arched Tunnel

In this study, a series of sidewall fire experiments were carried out in an arched tunnel, and the effect brought by the fire source height, the shape and the orientation of oil pool on flame length and transverse temperature were investigated. The results show that when the long side of oil pool is parallel to sidewall, the height change of oil pool has less influence on flame under the arched ceiling, while it has a large influence under the horizontal ceiling in previous studies; when the long side of oil pool is perpendicular to sidewall, the flame bifurcates with a large aspect ratio and entrains more fresh air, and the mass loss rate increases dramatically. The height change of oil pool has less influence on the flame when the long side of oil pool is parallel to sidewall, while it has great influence when the long side of oil pool is perpendicular to sidewall. Besides, the dimensionless heat release rates of fire source are modified and the flame length formulas are obtained under the two orientations of oil pool. The equation of the transverse temperature distribution under arched ceiling was obtained by modifying the lateral travelling distance of the plume.