Influence of external wind on fire characteristics and smoke dynamics in a stairwell adjacent to a room

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A range of fire experiments were conducted to explore fire characteristics and smoke dynamics in a 1/6-scale stairwell adjacent to a room at different external wind velocities. The results indicated that the flame volume during the initial stage and the time taken for combustion to enter the steady stage both decrease with the increasing wind velocity. There are two opposite effects of the external wind on the fire combustion in a burning room adjacent to a stairwell. The inhibition effect plays an important role at lower wind velocities, leading to a decrease in the mass loss rate (MLR) of the pool fire. Conversely, the promotion effect dominates at higher wind velocities, resulting in an increase in the MLR. Stack effect and external wind demonstrate a synergistic relationship during experiments, and a correlation of the airflow velocity, wind velocity and heat release rate (HRR) is established. There are intersections in temperature curves at different wind velocities due to the smaller temperature decay rate in the stairwell and the lower smoke temperature near the pool fire at a higher velocity. Furthermore, a prediction model is also proposed for the smoke temperature distribution inside the stairwell, taking into account the wind velocity and HRR.