Fully Coupled Three-Dimensional Simulation of Downward Flame Spread over Combustible Material
Abstract
:1. Introduction
2. Experiment
2.1. Flame Spread
2.2. Surface Incident Radiation and Surface Emissivity
3. Modeling and Simulations
3.1. Problem Setup
3.2. Solid Phase Model
3.2.1. Heat and Mass Transfer
3.2.2. Formal Kinetics of Material Decomposition
- The first-order reaction model should be discarded for this experimental dataset.
- For ≈ 2 ( = 76.8 kJ/mol), the simulated curves attain its maximum at approximately the same temperatures as the experimental counterparts.
- Maximum reaction rates are best reproduced at = 2.5 ( = 98.9 kJ/mol).
- The decomposition onset is best replicated at = 3 ( = 122.6 kJ/mol).
- A further increase of the reaction order ( > 3) does not facilitate better agreement between the simulated and measured cures.
3.3. Gas Phase Model
4. Result
4.1. The Effect of Volatile Oxidation Kinetics
4.2. The Effect of Decomposition Kinetics of Combustible Material
4.3. The Effect of External Heating
4.4. Flame Impact on the Burning Material
5. Concluding Remarks
Author Contributions
Funding
Institutional Review Board Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
Nomenclature
pre-exponential factor (s−1) | |
specific heat (J/(kg·K)) | |
apparent activation energy (J/mol) | |
expansion factor (-) | |
conversion function (-) | |
incident radiation (kW/m2) | |
heat transfer coefficient (W/(m2·K)) | |
thermal conductivity (W/(m·K)) | |
mass flux of volatiles at the specimen surface (kg/(m2·s)) | |
molar mass (kg/mol) | |
heat flux (W/m2) | |
specific heat release rate per unit mass of virgin material (W/kg) | |
heat of combustion of volatile oxidation per unit mass of virgin material (J/kg) | |
pyrolysis reaction rate (s−1) | |
matrix polymer decomposition rate ((kg/s)/m2) | |
universal gas constant, 8.314 J/(mol∙K) | |
laminar burning velocity (m/s) | |
time (s) | |
volume of the mesh element (m3/m2) | |
flame propagation velocity (m/s) | |
gas flow velocity (m/s) | |
weighting factor (-) | |
flame front coordinate (m) | |
mass fraction (-) | |
Greek | |
conversion (-) | |
heating rate (K/s) | |
emissivity (-) | |
porosity (-) | |
absorption coefficient (m−1) | |
mass fraction of matrix polymer converted to volatiles (-) | |
density (kg/m3) | |
Stefan–Boltzmann constant, 5.67 × 10−8 W/(m2·K4) | |
time scale (s) | |
Subscripts | |
convective | |
char | |
conductive | |
critical | |
flame | |
fiber | |
heat flux sensor | |
gas; gasification | |
incident | |
solid component (mp, fib, ch) | |
reaction number | |
matrix polymer | |
net value (radiative plus convective) | |
pyrolysis | |
radiative | |
solid residue | |
solid | |
surface | |
thermocouple | |
initial; ambient | |
final | |
Abbreviations | |
CFD | computational fluid dynamics |
MCC | microscale combustion calorimetry |
TGA | thermogravimetric analysis |
TC | thermocouple |
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Reaction | , kJ/mol | , kJ/kg | |||
---|---|---|---|---|---|
1 | 1.7 | 20.98 | 116.0 | 0.314 | 5.95 |
2 | 1.8 | 29.43 | 168.2 | 0.509 | 9.64 |
3 | 1.5 | 11.78 | 101.8 | 0.177 | 3.36 |
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Snegirev, A.; Kuznetsov, E.; Korobeinichev, O.; Shmakov, A.; Paletsky, A.; Shvartsberg, V.; Trubachev, S. Fully Coupled Three-Dimensional Simulation of Downward Flame Spread over Combustible Material. Polymers 2022, 14, 4136. https://doi.org/10.3390/polym14194136
Snegirev A, Kuznetsov E, Korobeinichev O, Shmakov A, Paletsky A, Shvartsberg V, Trubachev S. Fully Coupled Three-Dimensional Simulation of Downward Flame Spread over Combustible Material. Polymers. 2022; 14(19):4136. https://doi.org/10.3390/polym14194136
Chicago/Turabian StyleSnegirev, A., E. Kuznetsov, O. Korobeinichev, A. Shmakov, A. Paletsky, V. Shvartsberg, and S. Trubachev. 2022. "Fully Coupled Three-Dimensional Simulation of Downward Flame Spread over Combustible Material" Polymers 14, no. 19: 4136. https://doi.org/10.3390/polym14194136