Effect of horizontal projection's vertical location on the characteristics of externally venting flames

Abstract

The effect of the vertical position of horizontal projections on the thermal and flow characteristics of Externally Venting Flames (EVF) was investigated by using a ¼ scale compartment-façade experimental setup to perform five fire tests. A constant 144 kW fire power level was used in all fire tests; the fire source was a methane-fed porous burner, located at the geometrical centre of the compartment. A broad variety of measuring sensors was employed to determine the thermal and flow characteristics of the developing EVF. A parametric study was performed, aiming to evaluate the impact of the horizontal projection's “height above lintel” and “depth” on the EVF characteristics; two “height above lintel” and two “depth” values were investigated. Using an in-house developed image processing software tool, flame intermittency contour plots were produced, allowing the determination of EVF height, horizontal projection and width values. The EVF external dimensions were compared to the respective values predicted by correlations proposed in Eurocode (EN 1991-1-2); large discrepancies were found, especially for EVF projection and width. The Eurocode predictions for the EVF width and, occasionally, the EVF height, were found to yield markedly non-conservative values, thus rendering them inappropriate for fire engineering design purposes.