Heat fluxes and flame heights in façades from fires in enclosures of varying geometry

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.

Section: Matec Web Of Conferencesmentioning

confidence: 99%

Section: The Global Non-dimensional Factor Kmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Tang

et al. 2013

“…A lot of work has been carried out to investigate the window-ejected flame and plume upon the exterior walls above the opening [4][5][6][7][8]. Correlations were also developed to characterize flame heights, plume temperatures and heat fluxes upon the facade based on a large amount of small-scale tests [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Experimental study of window-ejected flame and plume on glass curtain walls

Lei

2016

Abstract. This research presents an experimental study to investigate the performance of glass curtain walls exposed to exterior flame and plume ejected from windows. A test facility with 3-storey in height was constructed using steel frame to perform full-scale tests. Ventilation-controlled fire scenarios were designed to generate exterior flame and plume ejected from the burning room through a window opening. To characterize potential threats from window-ejected flame and plume to the glass curtain walls of upper floors, temperature, heat flux and air velocity at different heights above the opening upon curtain walls were measured during each test. The effects of window aspect ratio, horizontal projection were studied. It was found that the window with large aspect ratio provided more severe threat to the curtain walls on upper floors. A horizontal projection of 0.5m in depth was able to protect the glass on the upper floor from breaking.

“…For ignition source factor, Lee [3][4][5] has analyzed of the spreading mechanism of window fires (the external wall insulation system fire is usually started by window fires) and proposed a new length scale for correlating window fire's flame height, plume temperature and heat flux. Himoto [6] considered pressure gradient effect of window fire plume, and proposed a model for predicting the trajectory of window flame ejected from a fire compartment.…”

Section: Introductionmentioning

confidence: 99%

Experimental study and advanced CFD simulation of fire safety performance of building external wall insulation system

Yan¹,

Zhao

Liu

et al. 2013

Abstract. Large scale fire tests of building external wall insulation system were conducted. In the experiment, thermal-couples were mounted to measure the insulation system surface temperature and the gas temperature inside rooms at the second and third floors. Photos were also taken during the fire tests. The measurement provides information of the ignition and fire spread of the external insulation system which consists of surface protection layer, glass fibre net, bonding thin layer, anchor and the load bearing wall.Comprehensive simulations of the fire tests were carried out using an advanced CFD fire simulation software Simtec (Simulation of Thermal Engineering Complex) [1,2], which is now released by Simtec Soft Sweden, with the turbulent flow, turbulent combustion, thermal radiation, soot formation, convective heat transfer, the fully coupled three dimensional heat transfer inside solid materials, the 'burn-out' of the surface protection layer and the pyrolysis of the insulation layer, etc, all computed.The simulation is compared with experimental measurement for validation. The simulation well captured the burning and fire spread of the external insulation wall.