Turbulent Diffusion Flames Far from Chemical Equilibrium

这项工作的发展，测试，并使用湍流燃烧 一个解释远离平衡效应的模型， 包括局部灭绝。 工作的出发点 是联合概率的模型传输方程 速度和成分的密度函数（pdf）。 在 以前的工作这个方程已经解决了一个蒙特卡罗 一种计算近平衡点性质的方法 湍流扩散火焰 为了能够说明 对于远离平衡的效应，这种pdf方法是 延伸到两个方面。 第一，改进的混合模型， 说明反应对混合的影响，将是 开发、测试和整合。 第二，四步 将纳入甲烷/空气燃烧方案。 柴油机燃烧中的一些重要现象， 燃气轮机燃烧室与远离 平衡效应 例如点火、熄火、 重新点燃，排放大量的一氧化碳和 未燃烧的碳氢化合物。 虽然这项研究涉及 特别是湍流火焰，成功将有一个 对各种相关问题的影响， 湍流力学 改善湍流 反过来，建模将对推进系统产生影响 （内燃机、火箭和涡轮机），酸 雨（无论是在物种的形成和随后的 在整个环境中的扩散），有毒废物的处置， 半导体和超导体制造技术，以及 医学，举几个例子。

This work develops, tests, and uses a turbulent combustion model that accounts for far-from-equilibrium effects, including local extinction. The starting point of the work is the modelled transport equation for the joint probability density function (pdf) of velocity and compositions. In previous work this equation has been solved by a Monte Carlo method to calculate the properties of a near-equilibrium turbulent diffusion flame. In order to be able to account for far-from-equilibrium effects, this pdf approach is extended in two respects. First, an improved mixing model, that accounts for the effects of reactions on mixing, will be developed, tested, and incorporated. Second, a four-step scheme for methane/air combustion will be incorporated. Some important phenomena in diesel-engine combustion and in gas-turbine combustors are associated with far-from- equilibrium effects. Examples are ignition, blow-out, relight, and the emission of significant amounts of CO and unburnt hydrocarbons. Although this research deals specifically with turbulent flames, success will have an impact on related problems that span the wide spectrum of turbulent fluid mechanics. Improved turbulence modeling would have, in turn, an impact on propulsion systems (internal combustion engines, rockets, and turbines), on acid rain (both in formation of species and their subsequent dispersion throughout the environment), disposal of toxic wastes, semiconductor and superconductor fabrication techniques, and medical science, to cite a few.