Fire Plume in a Sharply Stratified Ambient Fluid
Abstract
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, the temperatures of the layers 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 > 0.88. This stratification
parameter is a function of the fire heat release, the density interface location and the
ambient stratification. The model also allows the plume height to be determined analyti-
cally. The comparison with the numerical data shows an excellent agreement. For practical
purposes, we finally propose a simplified correlation to estimate the height of the trapped
plume as a function of the interface height, the temperatures of the layers and the fire heat
release rate.
Domains
Reactive fluid environment
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