- Author
-
Emmons, H. W.
- Title
- Ceiling Jet in Fires.
- Coporate
- Harvard Univ., Cambridge, MA
- Sponsor
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
-
NIST GCR 90-582; Home Fire Proj. Tech. Rpt. 82
December 1990
51 p.
- Distribution
- Available from National Technical Information Service
- Contract
- NIST-GRANT-60NANB8D0845
- Keywords
-
ceiling jets
|
corridors
|
room fires
|
smoke movement
|
hydraulic approximation
- Abstract
- The steady ceiling jet is examined with a simplified "top hat" theory. Friction causes the jet to change downstream with flow, depth, and/or hydraulic jump adjustments to produce Richardson Number =1 at the corridor exit, just as in hydraulics. Entrainment has a qualitative effect identical to friction, although there are quantitative differences. Heat transfer has, however, the opposite effect; the Richardson Number moves away from 1 as the flow proceeds. When all effects are included, high friction cases are predictable, while low friction cases are not. New experimental studies are needed to locate the reasons.