Flame behavior and fire-induced flow field characteristic in building corridor fire with longitudinal partition

Corridors are of remarkable significance in connecting architectural space and improving urban operation efficiency for modern building systems, whereas the infrastructures are highly vulnerable to major fire accidents due to the high-density population and poor ventilation conditions. In this study, the flame behavior and fire-induced flow field characteristics in a 24-m corridor fire are numerically studied considering the effects of fire Heat Release Rate (HRR) and corridor layout. A special fire spread phenomenon, namely ghosting flame, is observed in the multi-room corridor. The result and theoretical analysis reveal that the ghosting flame is essentially triggered when the fire becomes ventilation-controlled at the innermost room but keeps fuel-controlled for the whole corridor from a global view. The ghosting flame occurrence and spread distance are determined by the required air supply rate and the actual air supply rate. When a ghosting flame occurs, the air supply rate is independent of the partition number and only increases with the HRR. An optimized estimation to the air inflow in the multi-rom corridor is proposed by modifying the flow coefficient Cd, and the density coefficient by considering the effects of Paired Vortex Structure (PVS) and smoke stratification, respectively. Based on the principle, a novel indicator, R, which represents the ratio of the required air supply rate and the air supply capability, is proposed to predict ghosting flame behaviors. The effectiveness of the proposed method is further validated by the previous experimental results. This work deepens the understanding of special fire spread phenomena in corridor spaces, improving the fire safety level for urban buildings.