颗粒群对森林可燃物的点燃特性影响研究

Spotting Ignition of Forest Fuels by Multiple Hot Steel Particles

摘要

飞火颗粒点燃森林可燃物是导致森林大火及森林-城镇交界域火灾发生的重要潜在途径.该研究重点关注在不同含水率和环境风作用下,不同初始质量的直径为 2 mm 热颗粒点燃松针燃料床的点燃现象及临界点燃极限.当环境风速为 2 m/s 时,随着燃料床含水率的增加,则需要更大的颗粒群总质量才能成功点燃松针燃料床.而随着风速的增加(0.5～8 m/s),颗粒群可以在更宽的散落区域面积内成功点燃.实验过程中未观察到点燃延滞时间与颗粒群散落区域面积间存在显著的关系,点燃延滞时间总体上随风速的增加而减小,但在 4～8 m/s 较高风速范围内趋于稳定.

Abstract

Ignition of forest fuels by firebrand particles is considered an important potential pathway for the occurrence and propagation of large wildfires and wildland-urban interface (WUI) fires. In this study, the ignition behavior and critical ignition limits of pine needle beds ignited by 2 mm hot particles with different initial total masses were investigated under varying fuel moisture contents and ambient wind conditions. At the wind speed of 2 m/s, successful ignition generally required a larger total mass of hot particles as the fuel moisture content increased. As the wind speed increased from 0.5 to 8 m/s, successful ignition was achieved over a wider dispersion area of hot particles. No significant dependence of ignition delay time on the dispersion area was observed. However, the ignition delay time decreased overall with increasing wind speed and tended to remain nearly constant at higher wind speeds of 4—8 m/s.

关键词

森林-城镇交界域火灾 / 热颗粒群 / 临界点燃极限 / 颗粒分布

Key words

WUI fires / hot steel particles / spotting ignition limit / particle distribution

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基金资助

国家重点研发计划资助项目(2023YFC3081600)

国家自然科学基金资助项目(52176113)