- Author
-
Cooper, L. Y.
- Title
- On the Significanes of a Wall Effect in Enclosures with Growing Fires.
- Coporate
- National Bureau of Standards, Gaithersburg, MD
- Journal
-
Combustion Science and Technology,
Vol. 40,
19-39,
1984
- Report
-
NBSIR 83-2730,
June 1983,
41 p.
- Distribution
- Available from National Technical Information Service
- Book or Conf
- American Society of Mechanical Engineers, Heat Transfer Division. Fire Dynamics and Heat Transfer. 21st National Heat Transfer Conference. July 24-28, 1983.,
American Society of Mechanical Engineers, New York,
Seattle, WA,
Quintiere, J. G., Alpert, R. L. and Altenkirch, R. A., Editors,
97-106 p.,
1983
- Keywords
-
compartment fires
|
enclosures
|
fire growth
|
mathematical modeling
|
smoke movement
- Abstract
- This paper studies the significance of a wall effect that has been obseved during the growth stage of enclosure fire experiments. Relative to the two-layer phenomenon which tends to develop during such experiments, the effect has to do with the near-wall downward injection of hot upper layer gases into the relatively cool uncontaminated lower layer. It is conjectured that these observed wall flows are buoyancy driven, and that they develop because of the relatively cool temperatures of the upper wall whose surfaces are in contact with the hot upper layer gases. For a growing fire (growth proportional to t(m); t being time and m is greater than or equal to 0) in an enclosed compartment, the conjectured mechanism for the wall flow leads to a time-dependent solution for the ratio of wall layer mass ejection rate from the upper layer, (M)w, to the fire plume mass injection rate to the upper layer, (m)p. The solution indicates that in practical fire scenarios m/m can be of the order of "several tenths" even prior to the time that the upper layer interface has dropped to an elevation midway between the ceiling and fire. In other words the results of the anlysis indicate the importance of taking the wall effect into account in two-layer zonal analyses of enclosure fire phenomena.