Large outdoor fires are an increasing danger to the built environment. Wildfires that spread into communities, labeled as Wildland-Urban Interface (WUI) fires, are an example of large outdoor fires. Other examples of large outdoor fires are urban fires including those that may occur after earthquakes as well as in informal settlements. When vegetation and structures burn in large outdoor fires, pieces of burning material, known as firebrands, are generated, become lofted, and may be carried by the wind. This results in showers of wind-driven firebrands that may land ahead of the fire front, igniting vegetation and structures, and spreading the fire very fast. Post-fire disaster studies indicate that firebrand showers are a significant factor in the fire spread of multiple large outdoor fires. The present paper provides a comprehensive literature summary on the role of firebrand mechanisms on large outdoor fire spread. Experiments, models, and simulations related to firebrand generation, lofting, burning, transport, deposition, and ignition of materials are reviewed. Japan, a country that has been greatly influenced by ignition induced by firebrands that have resulted in severe large outdoor fires, is also highlighted here as most of this knowledge remains not available in the English language literature. The paper closes with a summary of the key research needs on this globally important problem.

中文翻译：

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火源燃烧在大型室外火灾蔓延中的作用

大型户外火灾对建筑环境的威胁越来越大。蔓延到社区的野火被称为荒地与城市交界处 (WUI) 火灾，是大型室外火灾的一个例子。大型户外火灾的其他例子是城市火灾，包括地震后可能发生的火灾以及非正规住区的火灾。当植被和建筑物在室外大火中燃烧时，会产生燃烧材料（称为火把），并被风吹起。这会导致风驱动的火炬阵雨可能落在火锋之前，点燃植被和建筑物，并使火势迅速蔓延。火灾后研究表明，火势阵雨是多起大型室外火灾蔓延的重要因素。本文提供了关于火源机制在大规模室外火灾蔓延中的作用的全面文献总结。回顾了与材料的火种生成、放样、燃烧、运输、沉积和点燃相关的实验、模型和模拟。日本是一个深受火把引燃影响的国家，导致了严重的大型户外火灾，这里也强调了这一点，因为大部分这方面的知识在英语文献中仍然无法获得。本文最后总结了这一全球重要问题的关键研究需求。