Effects of water spray on smoke layer in buildings with natural venting

Abstract

Fire safety is always an important issue in the indoor and built environment. There might be hidden conflicts among different systems such as suppression and smoke control. The effect of water spray on smoke movement in halls with natural venting system is reported in this paper. A series of scale modelling experiments were carried out to study the temperature variation under water spray. A small vent on the opposite side of fire source would intensify smoke stratification and result in a higher smoke temperature. Water spray would weaken the smoke stratification due to the cooling effect on the smoke and the downward drag on the smoke layer. The temperature development of smoke was the result of competition of these two effects on the smoke layer. When the effect of water spray was stronger, the average smoke temperature tended to be lower, and the temperature difference of the ceiling to the smoke layer interface was smaller. When the effect of the opening dominated, the results were reversed. These results would be useful for providing fire safety in indoor and built environment.