Flame Heights In Wall Fires: Effects Of Width, Confinement And Pyrolysis Length

Coutin, M.; Delichatsios, M.

doi:10.3801/iafss.fss.6-729

Cited by 35 publications

(21 citation statements)

References 6 publications

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“…A small difference subsists between the values of the present C coefficient and Quintiere and Stecker data fitting. This variation can be attributed to errors on air m & determination due to diagnostic accuracy, but also, on the one hand to the difference between the theoretical heat release and the effective output power: a part of the heat of reaction is dissipated out of the room, on the other hand, heat release rate is a function of the hydrocarbon combustion efficiency, A χ [17]. It would be more adequate to use the chemical heat quantity ch Q & in…”

Section: Two Zones Hydrostatic Model (Stratified Flow Cases)mentioning

confidence: 99%

Aerodynamic Characterization Of A Compartment Fire As A Function Of Its Behavior

Coutin¹

2003

Fire Safety Science - Proceedings of the Seventh International

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An experimental setup is realized to study the behavior of a confined fire when the fire source is placed in combustion products trapped by a soffit, or located at the lower part of the rear wall of an enclosure. As a function of the source position, the flame, the heat release rate and the ventilation factor are drastically modified. In the first configuration, different flame behaviors are identified corresponding to jet flames, horizontal flames on the whole room surface at the level of the soffit, or extinction. In the second one, the wall fire interacts with the burnt gases close to the ceiling. The outwards hot smoke layer at the aperture always occupies one third of the open height. Based on the analysis of Babrauskas et al [1], a two zones hydrostatic model is developed, and a relation between the input air mass flow rate entering the room, the ventilation factor F v and the heat release rate Q

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Section: Two Zones Hydrostatic Model (Stratified Flow Cases)mentioning

confidence: 99%

Aerodynamic Characterization Of A Compartment Fire As A Function Of Its Behavior

Coutin¹

2003

Fire Safety Science - Proceedings of the Seventh International

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“…A CCD camera and an image-processing technique were employed to map flame presence probability and to determine the extent of the external combustion [14,15]. The image processing technique (CCD camera) to determine locations where the flame presence probability is equal to 50% was validated both by determining the center of the maximum standard deviation of fluctuations and by measuring the local flame gas temperature to be 500 0 C [16,17].…”

Section: Flame Heightmentioning

confidence: 99%

“…2). Moreover, based on the same definition as for the mean flame height [2], the width of the combustion region has been determined at the location where the flame presence probability is equal to 50%. For example, the profile obtained by the contour of the probability of the flame presence is illustrated in Fig.…”

Section: Off-center Heat Flux and Maximum Flame Widthmentioning

confidence: 99%

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Heat Flux Distribution And Flame Shapes On The Inert Facade

Lee¹,

Delichatsios²,

Silcock³

2008

Fire Saf. Sci.

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Fire spread in high rise buildings from floor to floor occurs if flames emerge and extend on the façade of the building to cause ignition in the floor above the floor where flashover has developed. Even though considerable effort has been exerted to address this issue, proposed relations for heat fluxes on façade are incomplete and contradictory because the relevant physics have been poorly clarified. By systematically performing a series small scale experiments having various enclosure geometries, door-like openings and fire locations, the physics and new relations are underpinned for the emerging flames on inert facades in ventilation controlled (under-ventilated) fires at the floor of fire origin. To limit the variables and uncertainties, propane and methane gas burners create a controlled (theoretical) heat release rate at the source. Gas temperatures inside the enclosure and at the opening, heat fluxes on the façade wall, flame contours (by a Charge Coupled Device camera-CCD camera) and heat release rates (by oxygen calorimetry) inside and outside the enclosure have been measured. The gas temperatures inside the enclosure were uniform for aspect ratio (length to width) of the enclosure from one to one to three to one. Previous relations for the air inflow and heat release rate inside the enclosure were verified. The flames are highly radiative because soot can be formed at high temperatures inside the enclosure before the combustion gases and the unburned fuel exit the enclosure. The heat fluxes on an inert façade, both at the centreline and off-center above the opening, have been well correlated by identifying two length scales. One related to the effective area of the outflow ( 1 ), and the other represented the length after which the flames turn from horizontal to vertical ( 3 ). Finally, Correlation of the maximum flame width which is valid for the case having aspect ratio of the opening (width to height) between 0.375 and 2 was proposed in this paper. The results can be used for engineering calculations for real fires and for validation of new large eddy scale simulation models. KEYWORDS

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“…Recently, a model of facade flame heights has been brought up by Delichatsios et al [12][13][14][15][16][17]. The flames on the facade eject from the compartment opening when the heat release rate in the compartment is higher than the critical value (1500A √ H kW) with the mean facade flame height determined by the excess fuel burning outside the opening as well as by the opening geometry of the compartment.…”

Section: Introductionmentioning

confidence: 99%

Effects of side walls on facade flame entrainment and flame height from opening in compartment fires

Tang

et al. 2013

MATEC Web of Conferences

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Abstract. This paper presents an investigation of the side wall effects on facade flames ejected from the opening (such as a window) of an under-ventilated room fire. Experiments are carried out in a reduced-scale experimental setup, consisting of a cubic fire compartment having an opening with a vertical facade wall and two side walls normal to the façade wall. By changing the distance of the two side walls, the facade flame heights for different opening conditions (width, height) are recorded by a CCD camera. It is found that as the distance of the two side walls decreases the behavior the flame height can be distinguished into two regimes characterized by the dimensionless excess heat release rate,Q * ex , outside the opening: (a) for the "wall fire" (Q * ex ≤ 1.3), the flame height is shown to change little with decrease of side wall distance as the dominant entrainment is from the front direction (normal to the facade wall) independent of the side wall distances; (b) for the "axis-symmetrical fire" (Q * ex > 1.3), the flame height increases significantly with a decrease in side wall distance as both the entrainment from the two side directions (parallel to the facade wall) and that from the front direction (normal to the facade wall) together apply. A global physically based non-dimensional factor K is then brought forward based on the side wall constraint effect on the facade flame entrainment to characterize the side wall effect on the flame height, by accounting for the dimensionless excess heat release rate, the characteristic length scales of the opening as well as the side wall separation distance. The experimental data for different opening dimensions and side wall distances collapse by using this global non-dimensional factor.

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Flame Heights In Wall Fires: Effects Of Width, Confinement And Pyrolysis Length

Cited by 35 publications

References 6 publications

Aerodynamic Characterization Of A Compartment Fire As A Function Of Its Behavior

Aerodynamic Characterization Of A Compartment Fire As A Function Of Its Behavior

Heat Flux Distribution And Flame Shapes On The Inert Facade

Effects of side walls on facade flame entrainment and flame height from opening in compartment fires

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