Investigation of Nitric Oxide Kinetics in Diffusion Flames with Laser-Induced Fluorescence Spectroscopy and Detailed Modeling

这个联合项目涉及密歇根大学、帝国理工学院（伦敦）和桑迪亚国家实验室（利弗莫尔），目的是提高对扩散和富燃料火焰中有利的提示（Fenimore）途径形成一氧化氮（NO）的理解和预测能力。测量了对提示机制至关重要的化学物质，并与详细的动力学模型的结果进行了比较。在稳定的扩散火焰中，使用非侵入式激光诊断测量NO、CH自由基和氧原子的温度和浓度。所研究的火焰是在tsuji型逆流燃烧器上稳定的甲烷/空气扩散火焰。用纳秒和皮秒激光诱导荧光（LIF）进行物种测量。用相干反斯托克斯拉曼光谱（CARS）测量温度，通过解析皮秒LIF信号的时间衰减直接测量淬火。使用瑞利散射（CH， o -原子）或通过测量已知数量的掺杂剂（NO）进行校准。调整火焰应变速率（空气和燃料流量）以提供各种反应条件，并将一氧化氮添加到燃料中以测量与碳氢化合物（再燃烧）反应对NO的破坏。减少污染物的排放，特别是氮氧化物的排放，是设计能源转换装置的关键问题，包括汽车发动机、燃气轮机和家庭采暖炉。根据火焰条件的不同，一氧化氮的形成可以通过两种不同的机制进行：热（Zeldovich）机制或提示（Fenimore）机制。热机制在燃料稀薄的预混系统中占主导地位，它的特性很好。然而，这一提示机制尚不清楚。

The objective of this joint project involving the University of Michigan, Imperial College (London), and Sandia National Laboratory (Livermore) is to improve understanding and predictive capability of nitric oxide (NO) formation from the prompt (Fenimore) pathway favored in diffusion and fuel-rich flames. Chemical species critical to the prompt mechanism are measured and compared to the results from detailed kinetic models. Temperature and concentrations of NO, CH radical, and oxygen atoms are measured in a stable diffusion flame using nonintrusive laser-based diagnostics. The flame studied is a methane/air diffusion flame stabilized on a Tsuji-type counterflow burner. Species measurements are made with nanosecond and picosecond laser-induced fluorescence (LIF). Temperatures are measured with coherent anti-Stokes Raman spectroscopy (CARS) and quenching is measured directly by resolving the temporal decay of the picosecond LIF signal. Calibration is performed using Rayleigh scattering (CH, O-atom) or by measuring known amounts of dopant (NO). Flame strain rates (air and fuel flows) are adjusted to provide various reaction conditions, and nitric oxide is added to the fuel to measure destruction of NO by reaction with hydrocarbons (reburn).Reduction of pollutant emissions, especially nitrogen oxides, is a key issue in the design of energy conversion devices including automobile engines, gas turbines, and home heating furnaces. Depending on flame conditions, formation of nitric oxide can proceed by two different mechanisms: the thermal (Zeldovich) mechanism or the prompt (Fenimore) mechanism. The thermal mechanism, which dominates in fuel-lean, premixed systems, is fairly well characterized. However, the prompt mechanism is poorly understood.