Firebrand ignition of wildland fuels is an important pathway of initiation and propagation of wildland and wildland-urban interface fires. The ambient wind plays an important role in smouldering ignition of wildland fuels by firebrands, but its influence is poorly stated. In this work, the effect of ambient wind on the ignition of a moist pine needle fuel bed by a glowing firebrand was investigated. Two ignition outcomes, smouldering or failed ignition, were observed. Wind was found to have a significant impact on the ignition process by affecting the glowing combustion state of the firebrand. As the wind velocity increased from zero to 4 m/s, the smouldering ignition probability firstly increased and then decreased, while the smouldering ignition delay time decreased. Under the same wind conditions, the ignition probability decreased while the smouldering ignition delay time increased as the fuel moisture content increased from 5.9% to 53.2%. A theoretical model based on the glowing combustion rate of firebrand and heat transfer between the firebrand and the fuel bed under the effect of wind was proposed. The model predicted the variation trend of the smoldering ignition delay time with the wind velocity well when FMC was less than 20%, but poor at higher FMC. It also predicted that the square root of ignition delay time had a good linear relationship with FMC. This work is a step forward in understanding of spot fires initiated by glowing firebrands.

荒地燃料的火种点燃是荒地和荒地-城市界面火灾引发和蔓延的重要途径。环境风在火把阴燃点燃野地燃料方面发挥着重要作用，但其影响却很少被阐明。在这项工作中，研究了环境风对发光火种点燃潮湿松针燃料床的影响。观察到两种点火结果：阴燃或点火失败。研究发现，风会影响火种的炽热燃烧状态，从而对点火过程产生重大影响。随着风速从0增大到4 m/s，阴燃着火概率先增大后减小，而阴燃着火延迟时间则减小。相同风力条件下，随着燃料含水量从5.9%增加到53.2%，着火概率降低，阴燃延迟时间增加。提出了基于风作用下火源炽热燃烧速率和火源与燃料床之间传热的理论模型。该模型在FMC小于20%时较好地预测了阴燃延迟时间随风速的变化趋势，但在较高FMC时则较差。并预测点火延迟时间的平方根与FMC具有良好的线性关系。这项工作在理解由发光火把引起的现场火灾方面向前迈出了一步。