Measurements and Prediction of Nitrogen Oxide Formation in Flickering Flames

摘要-米勒CTS - 9729578 闪烁，或随时间变化，火焰的数值模型的开发，该模型的目的是准确和有效地预测氮氧化物的排放水平。 该模型由三个部分组成：（1）通过求解质量、动量、能量和混合分数守恒方程来预测火焰结构;（2）应用小火焰库方法来预测碳、氢和氧的浓度;（3）后处理氮化学来预测氮氧化物的局部水平和排放。 非定常火焰结构预测使用自适应谱元离散的守恒方程的串行和并行机。 对现有的不可压缩谱元程序进行了修改，使其允许变密度。 在该过程中的每个步骤中，模型预测与甲烷燃料火焰上的可调谐二极管激光吸收光谱（TDLAS）的浓度测量值进行比较，包括一氧化碳，二氧化碳和甲烷的原位测量，以及使用脉冲石英微探针对火焰进行有条件采样以确定痕量氮物质（包括一氧化氮，二氧化氮，氨和氰化氢）的浓度。 这项工作介绍了一种新的计算方法的污染物的形成和火焰行为的建模。

Abstract - Miller CTS - 9729578 A numerical model for a flickering, or time-varying, flame is developed; this model is intended to accurately and efficiently predict emission levels for nitrogen oxides. The model consists of three sections: (1) prediction of flame structure through solution of conservation equations in mass, momentum, energy, and mixture fraction; (2) application of a flamelet library approach to predict concentrations of carbon, hydrogen, and oxygen species; and (3) post-processing nitrogen chemistry to predict local levels and emissions of nitrogen oxide species. The unsteady flame structure is predicted using an adaptive spectral element discretization of the conservation equations on both serial and parallel machines. The existing incompressible spectral element code is revised to permit variable density. At each step in the process, model predictions are compared with measurements of concentration from tunable-diode laser absorption spectroscopy (TDLAS) on a methane-fueled flame, including in situ measurements of carbon monoxide, carbon dioxide, and methane and conditional sampling of the flame using a pulsed quartz microprobe to determine concentrations of trace nitrogen species including nitric oxide, nitrogen dioxide, ammonia, and hydrogen cyanide. This effort introduces a new computational approach for the modelling of pollutant formation and flame behavior.