TY - JOUR
T1 - Review of the Transition From Smouldering to Flaming Combustion in Wildfires
AU - Christensen, Eirik G.
AU - Yang, Jiuling
AU - Rein, Guillermo
AU - Santoso, Muhammad Agung
N1 - Funding Information:
The authors would like to thank the European Research Council (ERC) Consolidator Grant HAZE (682587) for research funding and the Doctoral Studies Scholarship funded by the Indonesia Endowment Fund for Education (LPDP).
Funding Information:
The authors are grateful for the fruitful discussions with Dr. Haixiang Chen from the University of Science and Technology of China and with Dr. Francesco Restuccia, Dr. Hafiz M. F. Amin, Yuqi Hu, Matthew Bonner, Franz Richter, Dwi M. J. Purnomo, and Benjamin Khoo from Imperial College London. Funding. The authors would like to thank the European Research Council (ERC) Consolidator Grant HAZE (682587) for research funding and the Doctoral Studies Scholarship funded by the Indonesia Endowment Fund for Education (LPDP).
Publisher Copyright:
© Copyright © 2019 Santoso, Christensen, Yang and Rein.
PY - 2019/9/18
Y1 - 2019/9/18
N2 - Wildfires are uncontrolled combustion events occurring in the natural environment (forest, grassland, or peatland). The frequency and size of these fires are expected to increase globally due to changes in climate, land use, and population movements, posing a significant threat to people, property, resources, and the environment. Wildfires can be broadly divided into two types: smouldering (heterogeneous combustion) and flaming (homogeneous combustion). Both are important in wildfires, and despite being fundamentally different, one can lead to the other. The smouldering-to-flaming (StF) transition is a quick initiation of homogeneous gas-phase ignition preceded by smouldering combustion, and is considered a threat because the following sudden increase in spread rate, power, and hazard. StF transition needs sufficient oxygen supply, heat generation, and pyrolysis gases. The unpredictable nature of the StF transition, both temporally and spatially, poses a challenge in wildfire prevention and mitigation. For example, a flaming fire may rekindle through the StF transition of an undetected smouldering fire or glowing embers. The current understanding of the mechanisms leading to the transition is poor and mostly limited to experiments with samples smaller than 1.2 m. Broadly, the literature has identified the two variables that govern this transition, i.e., oxygen supply and heat flux. Wind has competing effects by increasing the oxygen supply, but simultaneously increasing cooling. The permeability of a fuel and its ability to remain consolidated during burning has also been found to influence the transition. Permeability controls oxygen penetration into the fuel, and consolidation allows the formation of internal pores where StF can take place. Considering the high complexity of the StF transition problem, more studies are needed on different types of fuel, especially on wildland fuels because most studied materials are synthetic polymers. This paper synthesises the research, presents the various StF transition characteristics already in the literature, and identifies specific topics in need of further research.
AB - Wildfires are uncontrolled combustion events occurring in the natural environment (forest, grassland, or peatland). The frequency and size of these fires are expected to increase globally due to changes in climate, land use, and population movements, posing a significant threat to people, property, resources, and the environment. Wildfires can be broadly divided into two types: smouldering (heterogeneous combustion) and flaming (homogeneous combustion). Both are important in wildfires, and despite being fundamentally different, one can lead to the other. The smouldering-to-flaming (StF) transition is a quick initiation of homogeneous gas-phase ignition preceded by smouldering combustion, and is considered a threat because the following sudden increase in spread rate, power, and hazard. StF transition needs sufficient oxygen supply, heat generation, and pyrolysis gases. The unpredictable nature of the StF transition, both temporally and spatially, poses a challenge in wildfire prevention and mitigation. For example, a flaming fire may rekindle through the StF transition of an undetected smouldering fire or glowing embers. The current understanding of the mechanisms leading to the transition is poor and mostly limited to experiments with samples smaller than 1.2 m. Broadly, the literature has identified the two variables that govern this transition, i.e., oxygen supply and heat flux. Wind has competing effects by increasing the oxygen supply, but simultaneously increasing cooling. The permeability of a fuel and its ability to remain consolidated during burning has also been found to influence the transition. Permeability controls oxygen penetration into the fuel, and consolidation allows the formation of internal pores where StF can take place. Considering the high complexity of the StF transition problem, more studies are needed on different types of fuel, especially on wildland fuels because most studied materials are synthetic polymers. This paper synthesises the research, presents the various StF transition characteristics already in the literature, and identifies specific topics in need of further research.
KW - fire
KW - flame
KW - forest
KW - polymer
KW - wildland urban interface
UR - http://www.scopus.com/inward/record.url?scp=85082930063&partnerID=8YFLogxK
U2 - 10.3389/fmech.2019.00049
DO - 10.3389/fmech.2019.00049
M3 - Review article
AN - SCOPUS:85082930063
SN - 2297-3079
VL - 5
JO - Frontiers in Mechanical Engineering
JF - Frontiers in Mechanical Engineering
M1 - 49
ER -