The numerical and experimental analysis of upward flame spread over the flat surface and the wavy surface

Zhu, Xiaotao; Jiang, Yong; Wang, Zilong; Xiong, Caiyi; Xia, Yu; Xu, Wu

doi:10.1016/j.jhazmat.2019.01.056

Cited by 14 publications

(2 citation statements)

References 30 publications

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“…For sample width greater than 5 cm, lateral diffusion (along the sample width) of the combustible gas product was deemed negligible. 29 However, flow entrainment and flame heat loss from the sides to the ambient and to the sample holders can still play a role on the burning characteristics. 30 In this work, only one sample width was tested.…”

Section: Methodsmentioning

confidence: 99%

Upward flame spread over discrete thin solids separated by heat-absorbing inert materials

Cui

Sharma

Liao

2023

Journal of Fire Sciences

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Flame spread over discrete solid fuels has been of key research interest in the past few decades. Most studies considered an array of discrete fuels separated by air gaps or heat-insulating inert materials. The effects of heat loss due to the discrete configuration are not well understood. The present study aims to bridge this knowledge gap. A series of experiments are performed using a vertical array of thin discrete fuels separated by heat-absorbing inert materials of different thicknesses. For comparisons, experiments are also performed using discrete fuels separated by air gaps and using continuous fuel. The flame base spread rate is found to be generally higher in discrete fuel than in continuous fuel configurations, due to a reduced fuel load per unit length. It is also found that the air and inert gaps have opposite effects on the solid burning rates. The air gaps break the no-slip boundary, allowing the laterally entrained buoyancy flow (normal to the sample surface) to push the flame closer to the samples. This leads to an enhanced heat flux on the sample surface and an increased solid burning rate. On the other hand, the inert materials retain the flow boundary profile and act as a heat sink during flame spread, thereby reducing the solid burning rate. As the inert thickness increases, flame spread rate and solid burning rate decrease. Based on these observations, an existing model for flame spread rate is updated by incorporating the heat-absorbing effects of the gaps. The correlation is validated using the experimental data.

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Section: Methodsmentioning

confidence: 99%

Upward flame spread over discrete thin solids separated by heat-absorbing inert materials

Cui

Sharma

Liao

2023

Journal of Fire Sciences

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“…The hot source is 0.02 m long and the length orients parallel to the y ‐axis. Prior to the simulation, a time step was set as 1 × 10 −4 seconds 34,35 . To improve the simulation efficiency and save computational time, the entire computational domain was equally separated into 10 small domains along the fuel length.…”

Section: Numerical Modelmentioning

confidence: 99%

Concurrent flame spread over vertically oriented paper sheet: The effect of sample thickness

2021

Self Cite

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Summary Packing or printing paper made out of cellulose is widely produced and used in daily life. The thickness of thin material affects the burning process significantly. Concurrent flame spread is an effective approach when analyzing and evaluating the fire hazard for combustible materials. Conducting this work will provide further understanding of the flame spread mechanism and reduce fire hazard. It will also enable investigation of the effect of sample thickness on concurrent flame spreading over the thin paper sheets experimentally. Numerically examining concurrent flame spread over thin paper sheet with varied thicknesses is also performed using Direct Numerical Simulation, which can provide more details on flame spread process. Qualitatively, the model predictions agree reasonably with the experiment in terms of the flame contour, burn duration, and flame spread rate. The moving rates of the flame base and pyrolysis front decrease with sample thickness both experimentally and numerically. The relationship between net heat flux, flame standoff distance, and solid burning rate is analyzed, with the burning rate exhibiting a similar trend to that of the net heat flux. A correlation of the flame net heat flux with the normalized distance in the pyrolysis region is also established where the flame heat flux displays a decay trend with the normalized space.

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Experimental Dimension and Boundary Analysis of Upward Flame Spread Over U-Shaped Facade in Energy-Saving Building Fires

Chen,

Nie,

Zhang

et al. 2024

Fire Technol

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The numerical and experimental analysis of upward flame spread over the flat surface and the wavy surface

Cited by 14 publications

References 30 publications

Upward flame spread over discrete thin solids separated by heat-absorbing inert materials

Upward flame spread over discrete thin solids separated by heat-absorbing inert materials

Concurrent flame spread over vertically oriented paper sheet: The effect of sample thickness

Experimental Dimension and Boundary Analysis of Upward Flame Spread Over U-Shaped Facade in Energy-Saving Building Fires

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