Under-ventilated wall fire behaviour during the post-flashover period

This study assessed evolved behaviour of a strongly contained wall fire in an enclosure during the post flashover period. It characterised fire intensity decay up to extinction of a wall fire by lack of O2 and the effect of a sudden door opening on formation of an air gravity wave capable of causing the back-draft phenomenon. To better understand these 2 sequential fire scenarios, work was divided into 2 complementary parts performed 2012 in the same laboratory scale experimental set-up. The first part stabilised a steady wall fire at the rear of the compartment and followed its evolution when a door closes the aperture leaving only a thin slot opened to limit air entrance. Formation of a ghosting flame was observed moving through the compartment before dying at the aperture. By supposing the continuation of fuel solid pyrolysis after flame extinction due to radiation of the hot environment, fuel vapours continue to fill the compartment. The second part assessed the effect of re-opening the door. The formation and propagation of a gravity wave through the enclosure was observed and characterised. This development was representative of the first stage of a back-draft. Tests measured the aerodynamic properties of flow behaviour.

Authors: Most, J. M.; Saulnier, J. B ;Full Source: Journal of Applied Fluid Mechanics 2011, 4(2), 129-135 (Eng) ;