An experimental study on the effect of fire growth in a lower-floor compartment on fire evolution and facade flame ejection from an upper-floor compartment

The present study investigated the effect of fire growth in a lower-floor compartment on fire evolution and the characteristics of facade flame ejection from an upper-floor compartment. Experiments were performed using two floors with identical compartments (0.4 m cubic with an opening of 0.2 m x 0.2 m). A 0.2-m square porous propane burner was used as fire source in each compartment. Results showed that the growth of facade fire plume from the lower-floor compartment significantly affected the ventilation conditions for the opening of upper-floor compartment hence its fire evolution and facade flame ejection characteristics. These evolutions were found to be of three distinct types with HRR increasing in the lower-floor compartment: (I) in the case of relatively small upper-floor compartment fires under well-ventilated conditions. the flame was gradually weakened and finally extinguished; (II) in the case of medium upper-floor compartment fires under well-ventilated conditions, the flame inside the compartment (well-ventilated) turned to eject through the opening (under-ventilated), and the facade flame height decreased slightly till the flame was extinguished; (III) in the case of relatively large upper-floor compartment fires in under-ventilated conditions, the facade flame was sustained, and once the lower-floor compartment fire was involved, the flame height first increased significantly, then decreased, and finally increased again after the two facade flames from the two floors merged. The critical HRR of lower-floor compartment for realising flame ejection from upper-floor compartment (type II) was lower as the HRR of the upper-floor compartment is higher. The critical HRR of the lower-floor compartment for realising flame extinction of upper-floor compartment was found to be independent of the HRR of upper-floor compartment for type-I evolution while it increased with the HRR of the upper-floor compartment for type-II evolution. These new observations are essential for understanding building fire involving compartments of two floors. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.