Asymptotic Analysis of Flame Structure with Real Chemistry

本研究采用渐近方法，涉及扩展 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。 通过 无量纲化的守恒方程，大， 识别小参数。这些参数包括 导致活化能渐近的活化能， 导致达姆科勒数的反应速率的大小 渐近性，以及导致速率的反应速率比- 比率渐近性 基本步骤的速率参数为 取自反应速率实验的文献。 的 参数极限值的确定简化了 守恒方程，并使解决方案， 在很大程度上是通过分析获得的，而不需要借助于数值计算。 完整的守恒方程组的积分。 的 研究将解决预混物之间的结构差异 烃氧氮火焰和扩散火焰 涉及一氧化碳、氢气和 氧，以及固有的稳定性和影响 为这些火焰而紧张。 将特别注意 有效的简化格式的推导和应用 氢-氧系统，用于含卤素的系统，用于 高级烃，也可能用于甲醇。 这些方法通常会导致公式的数量 兴趣，如燃烧速度，和公式通常 包含由数值积分确定的参数 常微分两点边值问题 方程 由于这些微分方程非常复杂， 比初始微分方程更简单，完整 参数解，而不是解 仅限于特定条件。 因此，更好的 了解火焰的结构， 的燃烧过程被确定，并不重要， 消除了不起重要作用的并发症。

This research applies asymptotic methods, involving expansions for large and small values of parameters appearing in differential equations, to the analysis of structures of flames in real combustible mixtures. Through nondimensionalization of the conservation equations, large and small parameters are identified. These parameters involve activation energies leading to activation-energy asymptotics, magnitudes of reaction rates leading to Damkohler-number asymptotics, and ratios of reaction rates leading to rate- ratio asymptotics. Rate parameters for elementary steps are taken from the literature on reaction rate experiments. The identification of limiting values of the parameters simplifies the conservation equations and enables solutions to be obtained largely analytically without resort to numerical integration of the full set of conservation equations. The research will address structural differences between premixed flames and diffusion flames for hydrocarbon-oxygen-nitrogen systems for systems involving carbon monoxide, hydrogen and oxygen, as well as the intrinsic stability and influences of strain for these flames. Special attention will be paid to the derivation and application of useful reduced schemes for hydrogen-oxygen systems, for systems containing halogens, for higher hydrocarbons, and possibly also for methanol. The methods typically lead to formulas for the quantities of interest, such as burning velocities, and the formulas usually contain parameters determined by numerical integrations of two-point boundary-value problems for ordinary differential equations. Since these differential equations are much simpler than the starting differential equations, full parametric solutions are obtained, rather than solutions restricted to specific conditions. As a consequence, a better understanding of flame structure ensues, the essential aspects of the combustion processes are identified, and inessential complications that play no significant role are eliminated.