Premixed Flame Propagation in the Flamelet Regime

本研究的目的是了解层流火焰中发生的复杂火焰流相互作用，但对预混湍流燃烧有直接影响，特别是在小火焰状态下。用渐近技术和数值方法研究了模拟这些系统的模型。在这项工作中，考虑了两个问题。首先，研究了含有温度梯度或浓度梯度的混合物中预混边缘火焰的结构、动力学和消光。因为焓的变化会影响火焰温度，从而影响热敏化学反应的速率，它们会影响燃料消耗、火焰熄灭和化学污染物的排放；由于路易斯数、化学计量和热膨胀的影响也被检查。第二个问题是关于波塞维尔流中火焰的传播，其中火焰的传播取决于下伏流场的强度和规模。总燃烧速率、火焰形状和传播速度是我们感兴趣的参数，特别是在没有或存在热损失的情况下抑制闪回的条件下。

The objective of this research in to understand complex flame-flow interactions that occur in laminar flames but have direct implications to premixed turbulent combustion, particularly in the flamelet regime. Models simulating these systems are investigated using both asymptotic techniques and numerical methods. In this work, two problems are considered. In the first, the structure, dynamics, and extinction of premixed edge flames in mixtures containing gradients of temperature or concentration are investigated. Because enthalpy variations affect the flame temperature and hence the rates of thermally sensitive chemical reactions, they influence fuel consumption, flame quenching, and emission of chemical pollutants; effects due to Lewis number, stoichiometry, and thermal expansion are also examined. The second issue concerns flame propagation in Poiseuille flow in which flame propagation depends on the intensity and scale of the underlying flow field. Total burning rate, flame shape, and propagation speed are parameters of interest, especially under conditions in which flashback is suppressed in the absence or presence of heat losses.