- Author
-
Cooper, L. Y.
- Title
- Heat Transfer in Compartment Fires Near Regions of Ceiling-Jet Impingement on a Wall.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Journal
-
Journal of Heat Transfer,
Vol. 111,
455-460,
May 1989
- Keywords
-
walls
|
heat transfer
|
compartment fires
|
ceiling jets
|
stagnation point
|
flow rate
- Abstract
- The problem of heat transfer to walls from fire plume-driven ceiling jets during compartment fires is introduced. Estimates are obtained for the mass, momentum, and enthalpy flux of the ceiling jet immediately upstream of the ceiling-wall junction. An analogy is drawn between the flow dynamics and heat transfer at ceiling jet/wall impingement and at the line impingement of a wall and a two-dimensional, plane, free jet. Using the analogy, results from the literature on plane, free jet flows and corresponding wall-stagnation heat transfer rates are recast into a ceiling-jet/wall-impingement-problem formulation. This leads to a readily useable estimates for the heat transfer from the ceiling jet as it turns downward and begins its initial descent as a negatively buoyant flow along the compartment walls. Availble data from a reduced-scale experiment provide some limited verification of the heat transfer estimate. Depending on the proximity of a wall to the point of plume-ceiling impingement, the result indicate that for typical full-scale compartment fires with energy release rates in the range 200-2000 kW and fire-to-ceiling distances of 2-3 m, the rate of heat transfer to walls can be enhanced by a factor of 1.1-2.3 over the heat transfer to ceilings immediately upstream of ceiling jet-wall impingement.