When is the fire spreading and when it travels? – Numerical simulations of compartments with wood crib fire loads

Rahul Kallada Janardhan; Simo Hostikka

doi:10.1016/j.firesaf.2021.103485

When is the fire spreading and when it travels? – Numerical simulations of compartments with wood crib fire loads

Rahul Kallada Janardhan, Simo Hostikka^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › Scientific › peer-review

16 Citations (Scopus)

264 Downloads (Pure)

Abstract

The requirements for the occurrence of travelling fires and their distinction from previously recognized stages of fire development are not well understood. Here we present a CFD method that couples a fuel-area correction to a single-step wood pyrolysis model. The model was validated using SP medium-scale tunnel, demonstrating 19% under-prediction in peak HRR, and BST/FRS large-scale compartment where the predicted temperatures were within ±6% of the measurements. Detailed simulations of compartment geometries identified three modes of fire propagation: (1) With high ceiling heights, the ignition was followed by a fuel-controlled spread/travelling at speeds <1 cm/s (2) With lower ceiling heights, we observed a rapid (1–9 cm/s) spread towards the opening, driven by the smoke layer radiation and leading to a ventilation -controlled fire. (3) Finally, fire travelled back to the compartment interior at speed 0.1–0.9 cm/s, driven by large flames and controlled by the fuel-burnout. The analytical travelling fire model is designed to describe the first mode, but could also be used for modelling the back-travelling stage. Comparison between the CFD simulation and the analytical model indicates that further development of the analytical model is needed to account for the compartment's heating history and tunnel -like geometries.

Original language	English
Article number	103485
Number of pages	20
Journal	Fire Safety Journal
Volume	126
DOIs	https://doi.org/10.1016/j.firesaf.2021.103485
Publication status	Published - Dec 2021
MoE publication type	A1 Journal article-refereed

Funding

This work was funded by the Academy of Finland project no: 289037 and the Finnish Fire Protection Fund ( Palosuojelurahasto ). The authors would also like to acknowledge CSC-IT center for Science, Finland and Aalto Science-IT project for the large amount of computational resources provided for the study. We would also like to thank Prof. Haukur Ingason and Dr. Rickhard Hansen for providing us with test data for the SP tunnel fire tests. This work was funded by the Academy of Finland project no: 289037 and the Finnish Fire Protection Fund (Palosuojelurahasto). The authors would also like to acknowledge CSC-IT center for Science, Finland and Aalto Science-IT project for the large amount of computational resources provided for the study. We would also like to thank Prof. Haukur Ingason and Dr. Rickhard Hansen for providing us with test data for the SP tunnel fire tests.

Keywords

FDS
Fire spread
Single-step pyrolysis
Travelling fire
Ventilation
Wood cribs

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10.1016/j.firesaf.2021.103485Licence: CC BY

1-s2.0-S0379711221002277-mainFinal published version, 17.8 MBLicence: CC BY

Cite this

@article{74d19f70c5e343bf9347d4f607373903,

title = "When is the fire spreading and when it travels? – Numerical simulations of compartments with wood crib fire loads",

abstract = "The requirements for the occurrence of travelling fires and their distinction from previously recognized stages of fire development are not well understood. Here we present a CFD method that couples a fuel-area correction to a single-step wood pyrolysis model. The model was validated using SP medium-scale tunnel, demonstrating 19\% under-prediction in peak HRR, and BST/FRS large-scale compartment where the predicted temperatures were within ±6\% of the measurements. Detailed simulations of compartment geometries identified three modes of fire propagation: (1) With high ceiling heights, the ignition was followed by a fuel-controlled spread/travelling at speeds <1 cm/s (2) With lower ceiling heights, we observed a rapid (1–9 cm/s) spread towards the opening, driven by the smoke layer radiation and leading to a ventilation -controlled fire. (3) Finally, fire travelled back to the compartment interior at speed 0.1–0.9 cm/s, driven by large flames and controlled by the fuel-burnout. The analytical travelling fire model is designed to describe the first mode, but could also be used for modelling the back-travelling stage. Comparison between the CFD simulation and the analytical model indicates that further development of the analytical model is needed to account for the compartment's heating history and tunnel -like geometries.",

keywords = "FDS, Fire spread, Single-step pyrolysis, Travelling fire, Ventilation, Wood cribs",

author = "Janardhan, \{Rahul Kallada\} and Simo Hostikka",

note = "Funding Information: This work was funded by the Academy of Finland project no: 289037 and the Finnish Fire Protection Fund ( Palosuojelurahasto ). The authors would also like to acknowledge CSC-IT center for Science, Finland and Aalto Science-IT project for the large amount of computational resources provided for the study. We would also like to thank Prof. Haukur Ingason and Dr. Rickhard Hansen for providing us with test data for the SP tunnel fire tests. Funding Information: This work was funded by the Academy of Finland project no: 289037 and the Finnish Fire Protection Fund (Palosuojelurahasto). The authors would also like to acknowledge CSC-IT center for Science, Finland and Aalto Science-IT project for the large amount of computational resources provided for the study. We would also like to thank Prof. Haukur Ingason and Dr. Rickhard Hansen for providing us with test data for the SP tunnel fire tests. Publisher Copyright: {\textcopyright} 2021 The Authors",

year = "2021",

month = dec,

doi = "10.1016/j.firesaf.2021.103485",

language = "English",

volume = "126",

journal = "Fire Safety Journal",

issn = "0379-7112",

publisher = "Elsevier",

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T1 - When is the fire spreading and when it travels? – Numerical simulations of compartments with wood crib fire loads

AU - Janardhan, Rahul Kallada

AU - Hostikka, Simo

N1 - Funding Information: This work was funded by the Academy of Finland project no: 289037 and the Finnish Fire Protection Fund ( Palosuojelurahasto ). The authors would also like to acknowledge CSC-IT center for Science, Finland and Aalto Science-IT project for the large amount of computational resources provided for the study. We would also like to thank Prof. Haukur Ingason and Dr. Rickhard Hansen for providing us with test data for the SP tunnel fire tests. Funding Information: This work was funded by the Academy of Finland project no: 289037 and the Finnish Fire Protection Fund (Palosuojelurahasto). The authors would also like to acknowledge CSC-IT center for Science, Finland and Aalto Science-IT project for the large amount of computational resources provided for the study. We would also like to thank Prof. Haukur Ingason and Dr. Rickhard Hansen for providing us with test data for the SP tunnel fire tests. Publisher Copyright: © 2021 The Authors

PY - 2021/12

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N2 - The requirements for the occurrence of travelling fires and their distinction from previously recognized stages of fire development are not well understood. Here we present a CFD method that couples a fuel-area correction to a single-step wood pyrolysis model. The model was validated using SP medium-scale tunnel, demonstrating 19% under-prediction in peak HRR, and BST/FRS large-scale compartment where the predicted temperatures were within ±6% of the measurements. Detailed simulations of compartment geometries identified three modes of fire propagation: (1) With high ceiling heights, the ignition was followed by a fuel-controlled spread/travelling at speeds <1 cm/s (2) With lower ceiling heights, we observed a rapid (1–9 cm/s) spread towards the opening, driven by the smoke layer radiation and leading to a ventilation -controlled fire. (3) Finally, fire travelled back to the compartment interior at speed 0.1–0.9 cm/s, driven by large flames and controlled by the fuel-burnout. The analytical travelling fire model is designed to describe the first mode, but could also be used for modelling the back-travelling stage. Comparison between the CFD simulation and the analytical model indicates that further development of the analytical model is needed to account for the compartment's heating history and tunnel -like geometries.

AB - The requirements for the occurrence of travelling fires and their distinction from previously recognized stages of fire development are not well understood. Here we present a CFD method that couples a fuel-area correction to a single-step wood pyrolysis model. The model was validated using SP medium-scale tunnel, demonstrating 19% under-prediction in peak HRR, and BST/FRS large-scale compartment where the predicted temperatures were within ±6% of the measurements. Detailed simulations of compartment geometries identified three modes of fire propagation: (1) With high ceiling heights, the ignition was followed by a fuel-controlled spread/travelling at speeds <1 cm/s (2) With lower ceiling heights, we observed a rapid (1–9 cm/s) spread towards the opening, driven by the smoke layer radiation and leading to a ventilation -controlled fire. (3) Finally, fire travelled back to the compartment interior at speed 0.1–0.9 cm/s, driven by large flames and controlled by the fuel-burnout. The analytical travelling fire model is designed to describe the first mode, but could also be used for modelling the back-travelling stage. Comparison between the CFD simulation and the analytical model indicates that further development of the analytical model is needed to account for the compartment's heating history and tunnel -like geometries.

KW - FDS

KW - Fire spread

KW - Single-step pyrolysis

KW - Travelling fire

KW - Ventilation

KW - Wood cribs

UR - https://www.scopus.com/pages/publications/85118847820

U2 - 10.1016/j.firesaf.2021.103485

DO - 10.1016/j.firesaf.2021.103485

M3 - Article

AN - SCOPUS:85118847820

SN - 0379-7112

VL - 126

JO - Fire Safety Journal

JF - Fire Safety Journal

M1 - 103485

ER -

When is the fire spreading and when it travels? – Numerical simulations of compartments with wood crib fire loads

Abstract

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Keywords

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Robustness of advanced multi-storey steel-frame building in fire

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When is the fire spreading and when it travels? – Numerical simulations of compartments with wood crib fire loads

Abstract

Funding

Keywords

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Other files and links

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Robustness of advanced multi-storey steel-frame building in fire

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Science-IT

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