Combustion characteristics and flame stability at the microscale: a CFD study of premixed methane/air mixtures
Combustion characteristics and flame stability at the microscale: a CFD study of premixed methane/air mixtures
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DOI：
10.1016/j.ces.2002.12.005
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发表时间：
2003-11
影响因子：
4.7
通讯作者：
D. G. Norton;D. Vlachos
中科院分区：
文献类型：
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作者：
D. G. Norton;D. Vlachos
建立了微燃烧器的二维椭圆计算流体动力学（CFD）模型，研究了微燃烧器尺寸、壁材电导率和厚度、外部热损失和操作条件对燃烧特性和火焰稳定性的影响。我们发现，壁的导电性和厚度是非常重要的，因为它们决定了上游的传热，这是火焰点火和稳定所必需的，以及通过控制热点的存在来控制材料的完整性。火焰熄灭有两种模式：一种是空间全局类型，适用于大的壁面导热系数和/或低流速和井喷。结果表明，在微燃烧器内存在一个允许持续燃烧的狭窄流速范围。在某些条件下，即使在这些小尺度上也可以观察到大的横向和轴向梯度。在高热损失的情况下，观察到周期振荡接近消光。工程图描绘火焰稳定性，熄灭，和井喷被构建。最后提出设计建议。
A two-dimensional elliptic, computational fluid dynamics (CFD) model of a microburner is solved to study the effects of microburner dimensions, conductivity and thickness of wall materials, external heat losses, and operating conditions on combustion characteristics and flame stability. We have found that the wall conductivity and thickness are very important as they determine the upstream heat transfer, which is necessary for flame ignition and stability, and the material's integrity by controlling the existence of hot spots. Two modes of flame extinction occur: a spatially global type for large wall thermal conductivities and/or low flow velocities and blowout. It is shown that there exists a narrow range of flow velocities that permit sustained combustion within a microburner. Large transverse and axial gradients are observed even at these small scales under certain conditions. Periodic oscillations are observed near extinction in cases of high heat loss. Engineering maps that delineate flame stability, extinction, and blowout are constructed. Design recommendations are finally made.