论文标题
点火和燃烧活燃料的阶段和时间尺度
Phases and Time-Scales of Ignition and Burning of Live Fuels
论文作者
论文摘要
Wildland大火影响全球生态系统和社区。许多野火在生活中燃烧或生活和衰老植被的混合物。因此，有必要了解活燃料的燃烧行为，而仅仅是死亡或干燃料，以更有效地支持消防管理决策。在这项研究中，评估了放置在对流热通量中的针头的点火和燃烧行为。 The species included longleaf pine (Pinus palustris), Douglas-fir (Pseudotsuga menziesii), western red cedar (Thuja plicata), ponderosa pine (Pinus ponderosa), western larch (Larix occidentalis), pacific yew (Taxus brevifolia), white spruce (Picea glauca), and sagebrush (Artemisia三叉戟）。点火和燃烧行为与活燃料水分含量（LFMC），飞行员火焰温度和对流热通量有关。使用高速成像捕获了点火和燃烧的不同阶段。通常，可以观察到四个燃烧阶段：液滴射血和燃烧，过渡阶段，燃烧燃烧和闷烧的燃烧。仅在活燃料中持续燃烧点火之前，可以在液滴的燃烧和随后的燃烧。对于某些物种（例如，长叶松树，黄松，白云杉）液滴弹性和燃烧可以减少相对于LFMC干燥燃料的点火时间。通常，过渡阶段倾向于比火焰和液滴相需要更长的时间（当发生时）。在过渡阶段，燃料被加热并发生热解。点火的时间尺度和点火和燃烧的不同阶段在现场燃料中而不是死亡和干燥的燃料。该结论表明，其他参数，例如燃料的化学组成和结构形态，可能会显着影响活燃料的燃烧。
Wildland fires impact ecosystems and communities worldwide. Many wildfires burn in living or a mixture of living and senescent vegetation. Therefore, it is necessary to understand the burning behavior of living fuels, in contrast to just dead or dried fuels, to more effectively support fire management decisions. In this study, the ignition and burning behaviors of needles placed in convective heat flux were evaluated. The species included longleaf pine (Pinus palustris), Douglas-fir (Pseudotsuga menziesii), western red cedar (Thuja plicata), ponderosa pine (Pinus ponderosa), western larch (Larix occidentalis), pacific yew (Taxus brevifolia), white spruce (Picea glauca), and sagebrush (Artemisia tridentate). The ignition and burning behaviors were related to live fuel moisture content (LFMC), pilot flame temperatures, and convective heat fluxes. The different phases of ignition and burning were captured using high-speed imaging. In general, four burning phases can be observed: droplet ejection and burning, a transition phase, flaming combustion, and smoldering combustion. Ejection and subsequent burning of droplets can occur prior to sustained flaming ignition only in live fuels. For some species (e.g., longleaf pine, ponderosa pine, white spruce) droplet ejection and burning can reduce ignition times relative to dried fuel with lower LFMC. In general, the transition phase tends to take longer than the flaming and droplet phases (when these occur). During the transition phase, the fuels are heated and pyrolysis occurs. Time-scales to ignition and the different phases of ignition and burning vary more among live fuels than dead and dried fuels. This conclusion indicates that other parameters, such as chemical composition and structural morphology of the fuel, can significantly influence the burning of live fuels.
