Smoke distributions from fire plumes in uniform downdraft from a ceiling

This paper describes a reduced-scale study of the contamination field (“smoke”) arising from a fire source in a space where air normally flows vertically at uniform velocity in a near-laminar state from ceiling to floor, as in many industrial clean rooms. While the flames of the fire source were not visually affected by the downdraft of air, the distribution of combustion products (“smoke”), as assessed from the penetration of fire-generated carbon dioxide into the fire space, was strongly affected. The combustion products distributed into umbrella-shaped smoke clouds around the fire source, outside of which the air was not contaminated. The boundaries have been plotted in scaled coordinates, applicable to arbitrary ceiling height and, in one version, also a range of downdraft velocities.