Algorithm for Estimating the Plume Centerline Temperature and Ceiling Jet Temperature in the Presence of a Hot Upper Layer.
Algorithm for Estimating the Plume Centerline
Temperature and Ceiling Jet Temperature in the Presence
of a Hot Upper Layer.
Davis, W. D.; Notarianni, K. A.; Tapper, P. Z.
NISTIR 6178; 27 p. June 1998.
Available from: National Technical Information Service
(NTIS), Technology Administration, U.S. Department of
Commerce, Springfield, VA 22161.
1-800-553-6847 or 703-605-6000;
Order number: PB98-146152
aircraft hangars; ceiling jets; fire models; fire
plumes; pool fires; zone models; sprinkler activation
The analysis of recent experiments (NIST TN 1423) using
JP-5 and JP-8 pool fires performed in 15 m and 22 m high
hangars suggest that plume centerline temperature
correlations found in the computer fire model FPETool
under predict the ceiling temperature for large fires.
The analysis was based on the results of thirty-three
fire tests which had heat release rates ranging from 100
kW to 33 MW and ambient temperatures ranging from 8 deg
C to 31 deg C. The ceiling jet correlation also requries
modification since a comparison of predicted sprinkler
activation using FPETool to measured sprinkler
activation met with only limited success. It is shown
that using Evans' virtual source method coupled with a
radiative fraction correlation that depends on pool
diameter provides plume centerline temperature
predictions that agree with experiment. A modified
version of Alpert's ceiling jet correlation is presented
to account for changes in r/H dependence as the upper
layer develops. When an upper layer does not form, both
Alpert's and Heskestad's correlations provide good
agreement with the measure ceiling temperatures.