Fire smoke dispersion inside and outside of a warehouse building in moderate and strong wind conditions

Abstract

A moderate-sized (8 MW) fire was modelled in a warehouse located in an urban area with diverse architecture, in wind conditions. The investigation includes the effects of neighbouring architecture on the wind field, and in consequence on the smoke control performance and the smoke dispersion in the near-field of the building. Overall, 25 CFD simulations were performed with ANSYS Fluent CFD code, for wind velocities of 5 m/s (moderate), 10 m/s (strong) at 12 wind angles each (0°–330°, 30° increment), and at 0 m/s for reference. The building smoke venting system's performance was affected by the wind, reaching 74%–114% and 78%–158% of the reference mass flow at the moderate and strong wind velocities, respectively. Surprisingly, in multiple cases the exhaust flow rate of ventilators was increased, rather than hindered by the wind. We attribute this to the arrangement of inlets and outlets on façades and the resulting pressure difference between the wall and roof openings. The smoke plume was highly dependent on the wind angle, and the type of architecture up- and downwind of the fire. Significant urban canyon effects and large vortices forming behind tall buildings were observed, leading to smoke accumulation in a large distance from the fire.