Fire Plume in a Sharply Stratified Ambient Fluid

International audienceThe present work analyses theoretically and numerically fire plumes evolving in a two-layerstratified environment. The ambient fluid consists of a lower cold (heavy) layer and an upperwarm (light) layer with a sharp interface. The fire plume is controlled by the fire heat releaserate Q. Depending on the density interface location, the temperatures of the layers and onthe fire source conditions, the fire plume can rise indefinitely or can be captured by thedensity stratification. To determine a criterion between these two situations, a theoreticalmodel is proposed. With this model, it is found that the trapping/escaping criterion of thefire plume is determined in terms of a stratification parameter lambda > 0.88. This stratificationparameter is a function of the fire heat release, the density interface location and theambient stratification. The model also allows the plume height to be determined analyti-cally. The comparison with the numerical data shows an excellent agreement. For practicalpurposes, we finally propose a simplified correlation to estimate the height of the trappedplume as a function of the interface height, the temperatures of the layers and the fire heatrelease rate