Measurements and Prediction of Nitrogen Oxide Formation in Flickering Flames

摘要：建立了闪烁或时变火焰的数值模型；该模型旨在准确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)应用火焰文库方法预测碳、氢和氧的浓度；(3)对氮化学进行后处理，预测当地氮氧化物的水平和排放量。采用自适应谱元离散方法对串联和并联机上的守恒方程进行了火焰非定常结构的预测。现有的不可压缩谱元代码进行了修订，以允许可变密度。在过程的每一步，将模型预测与可调谐二极管激光吸收光谱（TDLAS）在甲烷燃料火焰上的浓度测量结果进行比较，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，以确定微量氮的浓度，包括一氧化氮，二氧化氮，氨和氰化氢。这一努力为污染物形成和火焰行为的建模引入了一种新的计算方法。

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.