Full-scale experimental and numerical study of the influence of beams depth on the smoke flow characteristics in a long-closed channel with lateral opening

This paper aims to study the influence of beams depth on the smoke flow characteristics in a long-closed channel with lateral opening and multiple ceiling beams. A series of full-scale experiments and numerical simulations with different fire heat release rates and beam depths were carried out. The influence of beams depth on the smoke spreading, the longitudinal ceiling temperature distribution , the maximum ceiling excess temperature, and the smoke mass flow along the channel were analyzed. Results show that the existence of the ceiling beams in the long channel with closed ends makes the smoke accumulate, which causes the time of the ceiling jet stage increase with the increase of beams depth. The longitudinal ceiling temperature decays faster and the maximum ceiling temperature rise becomes higher with the increasing depth of beams. Additionally, the prediction correlations of longitudinal ceiling temperature distribution and the maximum ceiling temperature rise in the long channel with ceiling beams were established. Based on the dimensional analysis, a quantitative correlation to predict the smoke mass flow under the beam is proposed considering both beam parameters (depth, width, and the distance from the fire source) and HRR. The smoke mass flow decreases with increased depth of beams due to the weakening of air entrainment , this phenomenon is distinct from the gradual increase of smoke mass flow observed in long channels with open sides. This study is anticipated to contribute to fire prevention and the understanding of the smoke flow pattern in the long-closed channel with lateral opening and ceiling beams.