Effects of distribution of bulk density and moisture content on shrub fires
Effects of distribution of bulk density and moisture content on shrub fires
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DOI：
10.1071/wf12040
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发表时间：
2013-08
影响因子：
3.1
通讯作者：
Ambarish Dahale;Selina C. Ferguson;B. Shotorban;S. Mahalingam
中科院分区：
文献类型：
--
作者：
Ambarish Dahale;Selina C. Ferguson;B. Shotorban;S. Mahalingam
详细描述了一个基于物理模型的公式，该模型能够预测火在单个凸起的冠状灌木中的蔓延。通过对固体燃料的流体动力学、燃烧、换热和热降解等控制方程进行数值求解，得到的模型预测值与实验结果吻合较好。在这项研究中，我们利用基于物理的模型来探索两个参数--固体燃料体积密度的空间变化和固体燃料水分含量--对静止大气中孤立灌木燃烧的重要性。结果表明，当考虑密度的空间变化或燃料含水率的变化时，孤立灌木内的垂直火灾蔓延速率和树冠内的起火时间是两个显著影响的全局参数。燃料燃烧量是另一个受燃料水分含量变化影响的参数，特别是当火焰通过水分含量超过40%的固体燃料传播时。确定了在存在较高的堆积密度和水分含量时导致传播速度降低的具体机制。
Formulation of a physics-based model, capable of predicting fire spread through a single elevated crown-like shrub, is described in detail. Predictions from the model, obtained by numerical solutions to governing equations of fluid dynamics, combustion, heat transfer and thermal degradation of solid fuel, are found to be in fairly good agreement with experimental results. In this study we utilise the physics-based model to explore the importance of two parameters – the spatial variation of solid fuel bulk density and the solid fuel moisture content – on the burning of an isolated shrub in quiescent atmosphere. The results suggest that vertical fire spread rate within an isolated shrub and the time to initiate ignition within the crown are two global parameters significantly affected when the spatial variation of the bulk density or the variation of fuel moisture content is taken into account. The amount of fuel burnt is another parameter affected by varying fuel moisture content, especially in the cases of fire propagating through solid fuel with moisture content exceeding 40%. The specific mechanisms responsible for the reduction in propagation speed in the presence of higher bulk densities and moisture content are identified.