Asymptotic Analyses of Flames with Real Chemistry

这个程序应用了渐近方法--参数展开 对于出现在 微分方程--结构分析 真实的可燃混合物中的火焰。 速率参数 基本的化学步骤取自文献， 化学动力学实验， 守恒方程的无量纲化， 识别适当的大参数和小参数。 这些 参数通常涉及活化能，导致 活化能渐近，或反应速率比 基本步骤，产生率比渐近。 参数极限值的确定简化了 守恒方程，并允许获得解决方案 在很大程度上是分析性，而不诉诸数值积分 完整的守恒方程组。 的方法 通常会导致感兴趣的量的公式， 例如燃烧速度和消光应变率，以及 这些公式通常包含由下式确定的参数： 两点边值问题的数值积分 常微分方程。 由于这些方程 比初始方程简单得多，完全参数化 解决方案，而不是解决方案局限于 具体条件。 因此，更好地了解火焰结构是 燃烧过程的基本方面是 确定的，和非必要的并发症，发挥没有 重要角色被删除。 这种方法具有 已完成在以前的研究臭氧分解 火焰，甲烷火焰，氢火焰， 例如，产生良好的四步和两步机制， 最后两个火焰，分别。 目前的方案将 解决高级碳氢化合物火焰、氢火焰， 卤素、涉及氮化学的火焰和甲醇 火焰，以及解决内在稳定性问题 以及应变对火焰的影响。 将特别注意 用于推导简化动力学方案， 燃烧设计应用的实践工程师。 在 此外，研究结果将有助于我们的一般知识 火焰传播的机制，火焰结构， 灭绝

This program applies asymptotic methods--parameter expansions for large and small values of parameters appearing in differential equations--to the analysis of structures of flames in real combustible mixtures. Rate parameters for elementary chemical steps are taken from literature on chemical-kinetic experiments, and through nondimensionalization of the conservation equations, appropriate large and small parameters are identified. These parameters typically involve activation energies, leading to activation-energy asymptotics, or ratios of reaction rates of elementary steps, yielding rate-ratio asymptotics. Identification of limiting values of the parameters simplifies the conservation equations and allows solutions to be obtained largely analytically, without resort to numerical integration of the full set of conservation equations. The methods typically lead to formulas for the quantities of interest, such as burning velocities and extinction strain rates, and the formulas usually contain parameters determined by numerical integrations of two-point boundary-value problems for ordinary differential equations. Since these equations are much simpler than the starting equations, full parametric solutions are obtained, rather than solutions restricted to specific conditions. As a consequence, better understanding of flame structure is developed, the essential aspects of the combustion process are identified, and non-essential complications that play no significant role are eliminated. This type of approach has been completed in a previous study for the ozone decomposition flame, for methane flames, and for hydrogen flames, for example, yielding good four-step and two-step mechanisms for the last two flames, respectively. The current program will address higher hydrocarbon flames, hydrogen flames containing halogens, flames involving nitrogen chemistry, and methanol flames, as well as addressing issues of intrinsic stability and influences of strain on flames. Special attention will be paid to the derivation of reduced kinetic schemes of use to the practicing engineer in combustion design applications. In addition, the results will contribute to our general knowledge of mechanisms of flame propagation, flame structure, and extinction.