Sample width and thickness effects on horizontal flame spread over a thin PMMA surface

Jiang, Lin; Miller, Colin H.; Gollner, Michael J.; Sun, Jinhua

doi:10.1016/j.proci.2016.06.157

Cited by 69 publications

(16 citation statements)

References 18 publications

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“…It is also found that the trends of X p in the warp and weft directions increase non-linearly until the pyrolysis front reaches the edge of the sample. This trend is different from some other studies using simultaneous ignition along one entire edge, 11,17,24 in which the horizontal flame spreading can attain a steady state after a short initial period. This discrepancy may primarily be due to the difference in ignition source and flame structure.…”

Section: Flame Spread Ratecontrasting

confidence: 99%

“…Fang et al 10 investigated horizontal flame spread characteristics over thin paper under varied oxygen concentrations and found a transition point for flame illumination, radiative heat flux and flame spread rate. Jiang et al 11 systematically studied the combined effects of sample width and thickness on horizontal flame spread over thin polymethyl methacrylate (PMMA), and demonstrated that the total heat flux first decreased and then increased as the width of samples increased. It can be seen that a minimum flame spread rate exists under a certain range of sample width for steady burning horizontal flame spread.…”

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confidence: 99%

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Experimental study of moisture content effects on horizontal flame spread over thin cotton fabric

Gao

Zhu

Hui

et al. 2018

Textile Research Journal

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In this paper, moisture content effects on horizontal flame spread were experimentally investigated using 0.245 mm thick, 28 cm tall and 28 cm wide untreated cotton fabric sheets with various moisture contents varying from 0 to 34%. The pyrolysis spread rates, flame heights and ignition times were obtained and analyzed. The corresponding results are as follows: as moisture content increases, the flame height and spread rate first increase and then decrease. In contrast, the ignition time shows an opposite trend with moisture content. The extreme values are observed in cases of 2% moisture content samples. Moreover, the flame spread rate in the warp direction is larger than that in the weft direction. For horizontal flame spread, the moisture content has the effect of consuming part of the heat feedback, which can play a role in reducing the flame spread rate; simultaneously, the moisture content can enlarge flame size and increase the convective heat transfer coefficient, thereby resulting in an increase in flame spread rate. The non-monotonous trend in pyrolysis spread rate is the result of competition between these effects.

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Section: Flame Spread Ratecontrasting

confidence: 99%

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confidence: 99%

Experimental study of moisture content effects on horizontal flame spread over thin cotton fabric

Gao

Zhu

Hui

et al. 2018

Textile Research Journal

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“…The PMMA was laser cut into samples of 70 cm in length of different widths (20 cm, 30 cm and 40 cm) as shown in table 1. The sample width was varied as the flame emissivity, according to Kirchhoff's law, is derived from the emission coefficient and the characteristic length of the sample [29], [31], [32]. Hence, the radiative fraction became more dominant when the sample width was increased, which according to Jiang et al [29], leads to an increased FSR, when they studied PMMA samples with widths between 5 and 10 cm.…”

Section: Dimensions Installation and Ignition Of The Pmma Samplesmentioning

confidence: 99%

Experimental study of flame spread underneath photovoltaic (PV) modules

Kristensen

Faudzi

Jomaas

2021

Fire Safety Journal

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The horizontal flame spread underneath a photovoltaic (PV) module (or a plate) was studied for various gap heights to understand the fundamental fire dynamics between it and a flat roof construction. In a number of experiments, an opaque black polymethyl methacrylate (PMMA) and a black stainless-steel plate were used as surrogate fuel and module, respectively. Additional experiments were conducted with actual PV modules to analyse the reproducibility of the surrogate results and to study the potential effect of the small fuel contribution from the PV modules. PMMA samples (70 cm long) of varying widths (20 cm, 30 cm and 40 cm) were ignited at one end, and flame spread rate, mass loss, radiative heat flux and temperatures were recorded. For the 30 cm wide samples, a reduction in gap height from 20 cm to 17 cm resulted in a significant increase in the flame spread rate (from 0.37 mm/s to 2.41 mm/s). A similar critical gap height (transition into a much faster flame spread rate) was identified for all widths. Thus, introducing gap height requirements into PV installation standards could offer an inexpensive and elegant design that could reduce the fire risk associated with PV modules on flat roofs significantly.

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“…Flame spread leads to fire growth and enlargement and it is a natural consequence of simultaneous heat and mass transfer processes between flames and fuels. Accurate predictive flame spread models for combustible materials in different configurations have been sought for long [1] and many computational studies have been conducted for various materials with different in-house [2]- [12] and open-source codes [13]. Although a better understanding on the flame spread dynamics has been gained in the last few decades, accurate modelling of a bench-scale experiment is still challenging because of the multi-physics and multi-scale nature of the problem.…”

Section: Introductionmentioning

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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Sample width and thickness effects on horizontal flame spread over a thin PMMA surface

Cited by 69 publications

References 18 publications

Experimental study of moisture content effects on horizontal flame spread over thin cotton fabric

Experimental study of moisture content effects on horizontal flame spread over thin cotton fabric

Experimental study of flame spread underneath photovoltaic (PV) modules

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

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