LAUSR

Abstract In this study, a series of experiments were conducted with varying number of pool fires and opening location (floor with ventilation openings) in a 21-story full-scale office building to study the transport phenomena and stratification of hot smoke in the stairwell. The experiments show that the flame of the pool fire inclines away from the side lobby door as pushed by the side air entrainment. The strength of stack effect in the stairwell initially increases, then decreases with the opening height increases. The rise in temperature in the stairwell can be divided into a lower and an upper region, depending on the location and attenuation effect of the upper opening. In the lower region, both the stack effect and turbulent mixing play important roles in the movement of hot smoke, whereas in contrast, in the upper region, turbulent mixing dominates. The equivalent heat release rate for hot smoke in the upper region is determined through theoretical analysis, and an integrated correlation is proposed for predicting the rise time of the smoke plume in the stairwell. These unique full-scale experiments provide crucial experimental data and empirical correlations that help the design of safer smoke ventilation systems for stairwells in a high-rise building.