Vertical flame spread on charring materials at different ambient temperatures

Mangs, Johan; Hostikka, Simo

doi:10.1002/fam.2127

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…Before being rated through large-scale tests, cables and more especially sheath materials are often assessed using small-scale lab tests such as Limiting Oxygen Index (LOI) [2], cone calorimeter [3][4][5][6][7][8][9][10][11], thermal analysis [9,12,13] and more recently microscale calorimeter (MCC) [14][15][16][17][18]. Other less conventional small and intermediate scale tests or methods have been also developed and used [19][20][21][22][23][24]. With regard to LOI, a common statement reports that cable sheathing exhibiting LOI value over 30 enables cables to meet most of large scale tests [2].…”

Section: Introductionmentioning

confidence: 99%

Fire behaviour of electrical cables in cone calorimeter: Influence of cables structure and layout

Magalie

Caro

Rodolphe

et al. 2018

Fire Safety Journal

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The fire performances of small telecom halogen-free cables were measured using cone calorimeter by changing several test conditions (heat flux, number and spacing of cables) and cable properties (sheath thickness and insulation mass). An analytical phenomenological fitting was proposed to predict accurately main fire performances (time-to-ignition, peaks of heat release rate and time to peak of heat release rate) from a set of 42 tests. The phenomenological model also assesses quantitatively the influence of different test conditions and cable properties. It appears that time-to-ignition is only dependent on heat flux. Moreover the influence of sheath is pointed out to delay the occurrence of the main peak of heat release rate corresponding to the decomposition of non-flame retarded insulation. The fitting allows better predicting the fire hazard in case of cables burning.

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Section: Introductionmentioning

confidence: 99%

Fire behaviour of electrical cables in cone calorimeter: Influence of cables structure and layout

Magalie

Caro

Rodolphe

et al. 2018

Fire Safety Journal

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“…Two sets of experiments are used for model validation: the ones conducted in a concealed flame spread apparatus were reported in [16] and [42]. Another, previously unpublished set of experiments was carried out in free space at room temperature.…”

Section: Methodsmentioning

confidence: 99%

“…The flame spread was found turbulent while its rate was deduced from visualisation, photograph and a measured temperature of 300 °C criterion in the experiments. More details on the experiments and comparisons to DNS are provided in [16] [42]. Given the spreading flames at steady state are found mainly turbulent, as shown in Figure 2, the effect of flow field turbulence is modelled using LES.…”

Section: Methodsmentioning

confidence: 99%

Embedded flame heat flux method for simulation of quasi-steady state vertical flame spread

Hostikka

2019

Fire Safety Journal

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Flame spread has been an important but unsolved problem for decades as its numerical solution requires simultaneous accurate solutions in solid and gas phases.In the current study, a numerical model involving gas-phase Large Eddy Simulation (LES) and comprehensive solid pyrolysis model was built as the first step of the research with a sufficient resolution for reproducing the flame spread rates in a set of upward flame spread experiments on birch rods. In the current conditions, the flame spread is dominated by the convective heat transfer and the predicted spread rates are thus sensitive to the heat transfer model. The convective and radiative heat fluxes during steady state were then extracted from the model results and used to improve the accuracy of coarse mesh simulations by embedding them as thermal boundary conditions for the solid phase. Three alternative techniques were investigated:Normalizing the heat flux profile with the length of the pyrolysis zone (fully coupled technique) resulted in accurate spread rates only if the initial pyrolysis zone was specified precisely and the gas phase resolution remained sufficiently fine. In the second, uncoupled technique, the length of the pyrolysis zone was fixed. Accurate steady state flame spread rates were then achieved regardless of the mesh resolution and the initial length of the pyrolysis zone. Finally, the most promising technique involved a normalized heat flux profile within the pyrolysis zone and a generalized heat flux function within the preheating zone. Correct spread rates were achieved with up to ten times increase in cell size regardless of the initial pyrolysis zone properties.

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“…Previous researchers have studied the influence of various factors on fire behaviors of thermal insulation materials. Mangs and Hostikka 5 investigated the influence of ambient temperature on vertical flame spread behaviors. Zhang et al 6 explored the influence of sample width on the horizontal flame spread over XPS surface and derived the heat transfer mechanism of sample width causing the acceleration of flame spread.…”

Section: Introductionmentioning

confidence: 99%

Effect of shielding rates on upward flame spread over extruded polystyrene foam in vertical channel and heat transfer mechanism

Peng

Yin

et al. 2020

Fire and Materials

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SUMMARY Fire hazard of extruded polystyrene (XPS) thermal insulation materials has aroused public concern. In order to develop flame spread theory and the guideline for fire risk assessment of XPS, an experimental study on upward flame spread behavior and heat transfer mechanism of XPS in a vertical channel with different frontal shielding rates was conducted. Maximum temperature at the place 2 cm from XPS surface and at the center of channel first increase and then decrease as the shielding rate rises. The former is higher than the latter. Experimental value of average flame height rises as the shielding rate increases. A model for predicting the flame height is built, and the predicted results are consistent with the experimental results. Moreover, the relation between flame height and pyrolysis height under different shielding rates is obtained. The flame spread rate rises as the shielding rate increases. A prediction model of flame spread rate is established, and its prediction results are more accurate compared with those from previous models. The model also predicts that radiative heat transfer is the dominant heat transfer mode, accounting for 93% of the total heat transfer. This work is beneficial for fire risk assessment and fire safety design of building façade.

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Vertical flame spread on charring materials at different ambient temperatures

Cited by 8 publications

References 13 publications

Fire behaviour of electrical cables in cone calorimeter: Influence of cables structure and layout

Fire behaviour of electrical cables in cone calorimeter: Influence of cables structure and layout

Embedded flame heat flux method for simulation of quasi-steady state vertical flame spread

Effect of shielding rates on upward flame spread over extruded polystyrene foam in vertical channel and heat transfer mechanism

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