Note on Improving Corridor Floor Predictions in a Zone Fire Model.
Note on Improving Corridor Floor Predictions in a Zone
Fire Model.
(433 K)
Forney, G. P.
NISTIR 6046; 32 p. July 1997.
Available from:
National Technical Information Service
Order number: PB97-196877
Keywords:
zone models; fire models; predictive models; corridors;
fire research; simulation
Abstract:
Presently, the Consolidated Fire and Smoke Transport
Model zone fire model (CFAST) assumes that smoke travels
instantly from one side of a compartment to another. As
a result, upper layers start forming in compartments
connected to the end of long corridor much sooner than
expected. This report documents a procedure for
estimating ceiling jet travel times so that initial
layer formation may be predicted more accurately in
compartments connected to long corridors. Standard
correlations are not suitable for predicting ceiling jet
velocities and temperatures in corridors because ceiling
jet time arrival at a distance r is proportional to r**2
in normal rooms (rooms with length to height ratio's
near one) and proportional to r in corridors (rooms with
large length to height ratios). Correlations are
derived by performing numerical experiments to estimate
ceiling jet arrival times, temperature fall off rates
and depths for cases with various initial ceiling jet
temperatures and depths. These correlations are used to
improve predictions of corridor smoke flow in the CFAST
zone fire model.
