Experiments and Numerical Simulations of Vertical Flame Spread on Charring Materials at Different Ambient Temperatures

Mangs, Johan; Hostikka, Simo

doi:10.3801/iaffs.fss.10-499

Cited by 4 publications

(14 citation statements)

References 10 publications

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“…In case of N2XCH cable, the highest coefficient of determination was 0.79, reflecting the fact that the temperature dependence of the rate of flame spread for this cable type was rather weak. Despite the slight deviation from the theoretical power law dependencies, the results are nevertheless consistent with the fact that the PVC cables are thermally thicker than the birch rods, which were previously characterized as thermally thin [13].…”

Section: Flame Spread Experimentssupporting

confidence: 87%

“…Horizontal 'error bars' on the right of the markers indicate maximum temperatures in the test channel before ignition of the propane burner (degree of cooling during test start-up). Vertical error bars for the PVC cable indicate one standard deviation as reported in [13].…”

Section: Flame Spread Experimentsmentioning

confidence: 99%

“…Figure 5 presents an example of a sequential temperature rise as the flame front proceeds along a PVC cable sample MCMK pre-heated to 190 C and an FRNC cable sample N2XCH pre-heated to 191 C. Because of the closed structure of the apparatus, direct visual observations of the flame are not possible. According to the numerical simulations of the birch rods [13], the flow inside the channel is mainly laminar but a transition to turbulent takes place in the fire plume. In the early phases of the test, the height of this transition is above the upper edge of the pyrolysis region but moves lower in course of time as the burning rate increases and the flow speed gets higher.…”

Section: Introductionmentioning

confidence: 99%

“…Cables studied were two types of PVC cables, MCMK and MMJ, and one cable type representing modern flame retardant non-corrosive (FRNC) cable technology, N2XCH. The experimental apparatus and initial results are reported in detail in [12] and also in [13].Another use of the new apparatus is to provide data for the validation of numerical simulation. The parameters of the pyrolysis models used in the simulations are usually determined from small-scale experiments, but the validation of the complete simulation tool must be performed in scenarios with strong coupling between the gas and solid phases.…”

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Vertical flame spread on charring materials at different ambient temperatures

Mangs

Hostikka

2012

Fire and Materials

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SUMMARY A new flame spread apparatus for the measurement of flame spread rates at different ambient temperatures is presented. A 2‐m long sample is pre‐heated with air to the desired temperature and ignited from its lower end with a small propane burner. The flame spread is traced with thermocouples in contact with the sample surface. The features and function of the new apparatus are described, as well as series of vertical flame spread experiments on cylindrical birch rods and electrical cables made of polyvinylchloride (PVC) and flame retardant non‐corrosive (FRNC) materials. Vertical flame spread rates 6–62 mm/s (temperature range 22–271 °C) were determined for birch samples, 3–24 mm/s (22–190 °C) for PVC cable samples, and 0–4 mm/s (22–293 °C) for FRNC cable samples. Small‐scale experiments with thermogravimetric analysis and cone calorimeter were performed to characterize the sample materials in terms of their thermal and fire behaviour. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Flame Spread Experimentssupporting

confidence: 87%

Section: Flame Spread Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Vertical flame spread on charring materials at different ambient temperatures

Mangs

Hostikka

2012

Fire and Materials

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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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A modified zone model on vertical cable tray fire in a confined compartment in the nuclear power plant

Huang

Ren

et al. 2018

Journal of Fire Sciences

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Room fire with vertical cable tray involves upward flame spread along the cable. Assessing the vertical cable tray fire hazard in confined spaces has been challenging because of the strong coupling between flame spread and heat transfer. Long computing time is required in using sophisticated field model with computational fluid dynamics. Therefore, developing an appropriate zone model in a cable room fire with experimental validation is required for engineering applications. In this study, a vertical cable tray fire in a confined compartment was simulated using a modified zone model along three new areas on having temporal variations of the fire position, upwardspreading cable flame considered as a burning source moving at a constant speed, and validated through full-scale experiments on vertical cable tray fire with two typical cable-line spacing. The modified zone model can predict accurately the upper-layer temperature in the compartment. The accuracy is at least 25% higher than the model with fixed fire position. The measured temperature at different heights started to decrease at different times, which was due to the vertical spreading of the cable flame. For interface height, the relative error and normalized Euclidean distance in the time-varying fire position model can be improved by 50%.

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Experiments and Numerical Simulations of Vertical Flame Spread on Charring Materials at Different Ambient Temperatures

Cited by 4 publications

References 10 publications

Vertical flame spread on charring materials at different ambient temperatures

Vertical flame spread on charring materials at different ambient temperatures

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

A modified zone model on vertical cable tray fire in a confined compartment in the nuclear power plant

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