Fire Safety Science Digital Archive

Detailed velocity and temperature measurements using cross-correlation velocimetry were obtained for unconfined ceiling jets under ceiling transient and steady-state conditions. Small fires of 0.5 to 2.0 kW were produced with a premixed methane-air burner. These measurements represent one of the most detailed studies of unconfined ceiling jets to date and seem to be in general agreement with large-scale data. Empirical correlations for the steady-state ceiling jet temperature and velocity profi1es are described herein. The correlations compare we1 1 with, and have improved, results from previous works. The maximum temperature may not be scaled as a function of fire-to-ceiling heights for large radial distances. Furthermore, the Gaussian and boundary 1ayer thermal and momentum thicknesses of the ceiling jet are not equal, contrary to the assumptions made in other works.