Theory of Combustion By Analytical Methods for Real Chemistry

本研究应用偏微分方程的数学方法来分析真实的可燃混合物燃烧过程的结构和稳定性。 扩散火焰，预混火焰和爆轰在不同的部分的研究。 速率参数的基本化学步骤进行评估，从文献上的化学动力学实验，并通过无量纲化的守恒方程，适当的大，小参数确定。 这些参数通常涉及活化能，导致活化能渐近，或反应速率的比率， 基本步骤，导致率比渐近。 参数的极限值的识别简化了守恒方程，并且使得能够在很大程度上解析地获得解，而不需要求助于守恒方程的完整集合的数值积分。 这些方法通常会导致感兴趣的量的公式，如燃烧速度，点火或熄灭应变率，以及稳定性的临界条件，并且公式通常包含由常微分方程的两点边值问题的数值积分确定的参数。 由于这些方程比初始方程简单得多，因此获得了全参数解，而不是仅限于特定条件的解。 因此，可以更好地了解火焰结构和稳定性，识别燃烧过程的重要方面，并消除不起重要作用的不必要的复杂情况。 这种方法现在已经完成了甲烷和氢气燃烧，例如，分别产生良好的四步和两步memchanisms。 新的研究将解决高级烃燃烧，高级醇燃烧，火焰中氮氧化物的产生，以及固有的爆震稳定性和应变对火焰的影响。 将特别注意有用的简化动力学方案的推导及其对火焰和爆震的影响。 此外，减少化学描述的影响卤素作为抑制剂或熄灭促进剂在氢火焰将得到解决。 结果与我们对火焰传播、火焰结构、火焰和爆轰不稳定性以及点火和熄火机理的认识相一致。

This research applies mathematical methods for partial differential equations to analysis of the structure and stability of combustion processes in real combustible mixtures. Diffusion flames, premixed flames and detonations are addressed in different parts of the research. Rate parameters for elementary chemical steps are evaluated from the 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, leading to rate-ratio asymptotics. 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 methods typically lead to formulas for the quantities of interest, such as burning velocities, ignition or extinction strain rates, and critical conditions for stability, 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 and stability is developed, the essential aspects of the combustion processes are identified, and nonessential complications that play no significant role are eliminated. This type of approach has now been completed for methane and hydrogen combustion, for example, yielding good four-step and two-step memchanisms, respectively. The new research will address higher hydrocarbon combustion, higher alcohol combustion, and production of oxides of nitrogen in flames, as well as intrinsic detonation stability and influences of strain on flames. Special attention will be paid to the derivation of useful reduced kinetic schemes and to their influences on flame and detonation. In addition, reduced chemistry for describing influences of halogens as inhibitors or extinction promoters in hydrogen flames will be addressed. The results constribute to our knowledge of mechanisms of flame propagation, flame structure, flame and detonation instabilities, and ignition and extinction.