Fire plume in a two-layer stratified environment
Résumé
The present work analyses theoretically and numerically fire plumes evolving in a two-layer
stratified environment. The ambient fluid consists of a lower cold (heavy) layer and an upper
warm (light) layer with a sharp interface. The fire plume is controlled by the fire heat release
rate Q. Depending on the density interface location Hl and on the fire source conditions,
the fire plume can rise indefinitely or can be captured by the density stratification. To
determine a criterion between these two situations, a theoretical model is proposed. With
this model, it is found that the trapping/escaping criterion of the fire plume is determined in
terms of a stratification parameter lambda> C3 where the constant C3 ≈ 0.88. The stratification
parameter is a function of the fire heat release, the density interface location Hl and the
ambient stratification. Moreover, the model also allows the plume height to be determined
analytically. The comparison with the numerical data shows an excellent agreement.
Domaines
Sciences de l'ingénieur [physics]
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