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Note on Improving Corridor Floor Predictions in a Zone Fire Model.


pdf icon 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.