Facade flame height and horizontal extending distance from opening of compartment fire with external sideward wind

Abstract

The present study investigated facade flame height and horizontal extending distance from opening of compartment fire with external sideward wind (parallel to facade). These two important parameters determine essentially the critical conditions that how far the flame can touch and ignite the combustible above or especially beside the opening with external sideward wind, which have not been quantified in the literature. Experiments were carried out employing a 0.4 m cubic compartment fire model with an attached facade (width: 1.2 m; height: 1.6 m) subject to external sideward wind provided by a wind tunnel. A propane porous burner was set inside the compartment as fire source. The facade flame height and horizontal extending distance were measured for 203 test conditions involving eight opening sizes (or ventilation factors: AH, A and H is area and height of the opening, respectively) at various heat release rates with external sideward wind speeds up to 3.0 m/s. It was found that the facade flame height just decreased with increase in sideward wind speed. However, the flame horizontal extending distance increased for relative large openings, but first increased then decreased for relative small openings, with increase in sideward wind speed in this range. A non-dimensional analysis was performed based on the physical mechanism of air entrainment change and tilting of the flame caused by external sideward wind. These facade flame quantities were shown to correlate well to two proposed non-dimensional numbers based on the analysis, i.e., the ratio of air entrainment caused by the sideward wind to that induced by flame buoyancy itself with no wind, and the wind Froude number representing flame tilting caused by the sideward wind. The experimental data and proposed correlations in the present study provide an essential base for quantifying facade fire characteristics under external sideward wind conditions.