Influence of Recirculation Zones on Flaming Ignition of Porous Wood Fuel Beds
Understanding environmental factors that control the ignition of fuel beds exposed to firebrands is necessary to help reduce the risk of losses of structures. Ignition by firebrands has been reported to be sensitive to wind, but identification and quantification of the physical cause(s) of such sens...
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MDPI AG
2025-03-01
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| Series: | Fire |
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| Online Access: | https://www.mdpi.com/2571-6255/8/4/141 |
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| author | Derek Bean David L. Blunck |
| author_facet | Derek Bean David L. Blunck |
| author_sort | Derek Bean |
| collection | DOAJ |
| description | Understanding environmental factors that control the ignition of fuel beds exposed to firebrands is necessary to help reduce the risk of losses of structures. Ignition by firebrands has been reported to be sensitive to wind, but identification and quantification of the physical cause(s) of such sensitivities are still limited. The objective of this study was to quantify the influence of wind speed and direction on the ignition of a fuel bed exposed to firebrands and to understand the causes of this sensitivity. Fuel beds of Douglas fir shavings were exposed to a firebrand surrogate (i.e., a resistive heater) to determine flaming ignition probability and time to ignition for three different wind speeds and three wind directions. Increases in wind speed above quiescent reduced the temperature required for flaming ignition. However, a wind speed threshold above which ignition probability decreased was observed for some wind directions. The temperatures required for flaming ignition to occur and the time to ignition were sensitive to the wind direction. High-speed images and corresponding CFD calculations indicated that ignition occurred in the regions with the most prominent recirculation zones. Thus, sensitivities to wind speed and direction are attributable to differences in the pyrolysate residence time as controlled by recirculation zones. The results indicate that the local flow characteristics can significantly influence ignition, and characterization of the freestream velocity alone may not be sufficient. |
| format | Article |
| id | doaj-art-6b6c82ffc3b44aac8eb2d5f357bb5829 |
| institution | OA Journals |
| issn | 2571-6255 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
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| series | Fire |
| spelling | doaj-art-6b6c82ffc3b44aac8eb2d5f357bb58292025-08-20T02:28:20ZengMDPI AGFire2571-62552025-03-018414110.3390/fire8040141Influence of Recirculation Zones on Flaming Ignition of Porous Wood Fuel BedsDerek Bean0David L. Blunck1School of Mechanical, Industrial, and Manufacturing Engineering, Oregon State University, Corvallis, OR 97331, USASchool of Mechanical, Industrial, and Manufacturing Engineering, Oregon State University, Corvallis, OR 97331, USAUnderstanding environmental factors that control the ignition of fuel beds exposed to firebrands is necessary to help reduce the risk of losses of structures. Ignition by firebrands has been reported to be sensitive to wind, but identification and quantification of the physical cause(s) of such sensitivities are still limited. The objective of this study was to quantify the influence of wind speed and direction on the ignition of a fuel bed exposed to firebrands and to understand the causes of this sensitivity. Fuel beds of Douglas fir shavings were exposed to a firebrand surrogate (i.e., a resistive heater) to determine flaming ignition probability and time to ignition for three different wind speeds and three wind directions. Increases in wind speed above quiescent reduced the temperature required for flaming ignition. However, a wind speed threshold above which ignition probability decreased was observed for some wind directions. The temperatures required for flaming ignition to occur and the time to ignition were sensitive to the wind direction. High-speed images and corresponding CFD calculations indicated that ignition occurred in the regions with the most prominent recirculation zones. Thus, sensitivities to wind speed and direction are attributable to differences in the pyrolysate residence time as controlled by recirculation zones. The results indicate that the local flow characteristics can significantly influence ignition, and characterization of the freestream velocity alone may not be sufficient.https://www.mdpi.com/2571-6255/8/4/141ignitionfirebrandfirewildfirewindWUI |
| spellingShingle | Derek Bean David L. Blunck Influence of Recirculation Zones on Flaming Ignition of Porous Wood Fuel Beds Fire ignition firebrand fire wildfire wind WUI |
| title | Influence of Recirculation Zones on Flaming Ignition of Porous Wood Fuel Beds |
| title_full | Influence of Recirculation Zones on Flaming Ignition of Porous Wood Fuel Beds |
| title_fullStr | Influence of Recirculation Zones on Flaming Ignition of Porous Wood Fuel Beds |
| title_full_unstemmed | Influence of Recirculation Zones on Flaming Ignition of Porous Wood Fuel Beds |
| title_short | Influence of Recirculation Zones on Flaming Ignition of Porous Wood Fuel Beds |
| title_sort | influence of recirculation zones on flaming ignition of porous wood fuel beds |
| topic | ignition firebrand fire wildfire wind WUI |
| url | https://www.mdpi.com/2571-6255/8/4/141 |
| work_keys_str_mv | AT derekbean influenceofrecirculationzonesonflamingignitionofporouswoodfuelbeds AT davidlblunck influenceofrecirculationzonesonflamingignitionofporouswoodfuelbeds |