Characterizing Firebrand Exposure from Wildland-Urban Interface (WUI) Fires: Results from the 2007 Angora Fire
Characterizing Firebrand Exposure from Wildland-Urban Interface (WUI) Fires: Results from the 2007 Angora Fire
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DOI：
10.1007/s10694-012-0295-4
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发表时间：
2014-01-01
期刊：
影响因子：
3.4
通讯作者：
Foote, Ethan I. D.
中科院分区：
文献类型：
--
作者：
Manzello, Samuel L.;Foote, Ethan I. D.
本研究探讨了在2007年安哥拉火灾，严重的荒地，城市界面火灾在加州的火把暴露的尺寸分布和其他特征。在401所直接接触界面火灾的房屋中，61%被摧毁，30%根本没有燃烧。一段时间以来，人们一直观察到风力驱动的火把雨点燃建筑物，以及野火发生前未燃烧植被中的“点火”。经验上量化暴露的严重程度或描述有多少、多大、持续时间和距离的火种引起关注的点火问题还不可能。然而，在安哥拉大火之后的几天里，一个从实际界面火灾中收集经验性纵火犯数据的独特机会出现了。对暴露于安哥拉火灾的材料的燃烧模式进行了数字分析，以确定燃烧物的尺寸分布。由于逐渐燃烧或熔化，某些燃烧模式的面积可能大于燃烧带，但假设燃烧模式面积的总体尺寸分布代表实际燃烧带尺寸。通过将安哥拉火灾中收集的材料部分暴露于实验室中使用独特的NIST Dragon放样和点火研究设施（NIST Dragon的LAIR设施）产生的风力驱动的火把，对这一假设进行了研究。将报告的燃烧剂粒度分布与NIST最近进行的实验室建筑点火研究和历史燃烧剂现场研究中的实验燃烧剂生成的燃烧剂粒度分布进行比较。这些数据是必要的，以形成有效和适当的界面火灾风险缓解措施的基础，以及模拟火灾蔓延。比较目前的野火保护建筑施工法规和测试标准。这项研究的最突出的结果是文件的一贯小尺寸的火把和密切相关的这些结果与实验产生的火把的大小。
This study examines the size distribution and other characteristics of firebrand exposure during the 2007 Angora fire, a severe wildland-urban interface fire in California. Of the 401 houses that received direct interface fire exposure 61% were destroyed and 30% did not burn at all. The ignition of buildings by wind-driven firebrand showers and the starting of "spot fires" in unburned vegetation ahead of wildfires have been observed for some time. Empirically quantifying the exposure severity or describing how many firebrands of what size and over what duration and distance cause ignition problems of concern has not yet been possible. However, a unique opportunity to gather empirical firebrand data from an actual interface fire evolved in the days immediately following the Angora fire. Digital analyses of burn patterns from materials exposed to the Angora fire were conducted to determine firebrand size distributions. It is probable that some burn patterns were larger in area than the firebrands due to progressive combustion or melting, but it was assumed that the overall size distributions of burn pattern areas were representative of actual firebrand sizes. This assumption was investigated by exposing sections of materials collected in the Angora fire to wind driven firebrands generated in the laboratory using the unique NIST Dragon's lofting and ignition research facility (NIST Dragon's LAIR facility). The firebrand size distributions reported were compared to firebrand size distributions from experimental firebrand generation in both recent laboratory building ignition studies conducted by NIST and from historical firebrand field studies. Such data is needed to form the basis of effective and appropriate interface fire hazard mitigation measures as well as modeling fire spread. Comparisons are made to current wildfire protection building construction regulations and test standards. The most salient result of this study is documentation of the consistently small size of firebrands and the close correlation of these results with the sizes of experimentally generated firebrands.