Characteristics of Externally Venting Flames and Their Effect on the Façade: A Detailed Experimental Study

Abstract

In a compartment fire, Externally Venting Flames (EVF) may significantly increase the risk of fire spreading to adjacent floors or buildings; EVF-induced risks are constantly growing due to the ever-increasing trend of using combustible materials in building facades. The main aim of this work is to investigate the fundamental physical phenomena associated with Externally Venting Flames (EVF) and the factors influencing their dynamic development. In this context, a series of fire tests is conducted in a medium-scale compartment-façade configuration; an n-hexane liquid pool fire is employed, aiming to realistically simulate an "expendable" fire source. A parametric study is performed by varying the fire load density (127.75, 255.5 and 511 MJ/m 2) and opening factor (0.071 and 0.033 m 3/2). Emphasis is given to characterization of the thermal field developing adjacent to the façade wall. Experimental results suggest that the three characteristic EVF phases, namely "internal flaming", "intermittent flame ejection" and "consistent external flaming", are mainly affected by the opening dimensions, whereas the fuel load has a notable impact on the fuel consumption rate and heat flux to the façade. Fuel consumption rates were found to increase with increasing fire load and opening area, whereas the global equivalence ratio increases with decreasing opening factor. The obtained extensive set of experimental data can be used to validate CFD fire models as well as to evaluate the accuracy of available fire design correlations.

Assessing smoke toxicity of burning combustibles by four expressions for fractional effective dose

“…The following can be observed: Based on Group A cone data, FED 4max gives the highest FED values, as shown in Figure 1. Some values of FED 2 and FED 3max in Group A are higher than FED 4avg based on cone data, as shown in Figure 2. Based on Group B data, some values of FED 3max are higher than FED 4max as shown in Figure 3. Those data were on armchair, 17 tunnel tests on wood and plastics, 22 and n ‐hexane tested in Reference 24 as highlighted in Table 2. Many values of FED 1 , FED 2 , FED 3max , and FED 3avg in Group B are higher than FED 4avg as shown in Figure 4. …”

“…Literature results 17‐27,39‐41 on toxic gases data are used to compute the FED values from the four equations. These include the cone calorimeter data on PMMA, 18 PE, 19 PU and PA6, 23 pine needles, 20 and fir wood 27 ; full‐scale burning tests data on armchair, 17 cardboard boxes with ABS and PSF 25 ; tunnel full‐scale tests data on plastic pallets and wood pallets, 21 wood, PE and PU 22 ; fiber reinforced polymer (FRP) and others 39‐41 …”

“…Many literature results are reported on toxic gases data 17‐27 measured by oxygen consumption method. Selected data of cone calorimeter on burning polymethyl methacrylate (PMMA), polyethylene (PE), polyurethane (PU), polyamide 6 (PA6), pine needles, polyester PES, and fir wood; of full‐scale burning tests on armchair, polystyrene (PS) and PU, aircraft cabin, aerosol, wood, Acrylonitrile Butadiene Styrene (ABS), PS foam (PSF), and PES; and of tunnel full‐scale tests on plastic pallets, wood pallets, wood, PE, and n ‐hexane 17‐27 were used to calculate FED from different equations. An appropriate method is then proposed to review the available expressions of FED for assessing smoke toxicity.…”

Assessment of Fire Engineering Design Correlations Used to Describe the Geometry and Thermal Characteristics of Externally Venting Flames

“…Externally Venting Flames are essentially flames that traverse an opening of the fire compartment and emerge to the ambient environment [7,20]. The basic compartment fire phenomena and resulting EVF shapes, as described in the majority of the currently available design guidelines, e.g.…”

“…The flame thickness is estimated, assuming a triangular EVF shape [9], using Eq. (20). Equation (19) is also used to estimate the convective heat transfer coefficient, by neglecting the last term, associated with the shape of the receiving surface (1/d eq = 1.0) [9].…”