Impact of Hydrogen and Carbon Monoxide on Lean Premixed Hydrocarbon Flames

本研究的目的是：(1)利用粒子测温和激光诱导荧光技术表征层流和轻度湍流条件下实验拉伸、稀薄、预混火焰的特征；(2)评估添加氢气或氢气/一氧化碳混合物对预混碳氢化合物（甲烷或丙烷）火焰的火焰稳定性和稀薄燃烧极限的增强作用；(3)开发和验证简化机制，以预测甲烷/氢/一氧化碳燃料混合物的火焰行为（包括熄灭）；(4)对不同刘易斯数的多组分燃料对火焰稳定性的影响进行分析。实验研究和随后的数值模型验证依赖于逆流、反向射流和预混火焰的详细表征。燃料进料中氢气和一氧化碳浓度的独立变化为探索和影响稀薄预混碳氢化合物燃烧的化学途径，特别是接近熄灭的燃烧提供了新的手段。利用激光多普勒测速仪探测了反流火焰的消光条件，利用红外敏感相机观测了微米级颗粒的辐射，测量了温度场。激光诱导荧光（LIF）沿着火焰中心线通过测量羟基和甲醛荧光信号来探测火焰结构。先前的研究表明，燃料流中少量的氢可以大大延长拉伸、预混火焰的稳定性极限，这表明这可能是一种提高精益、预混、干燥、低nox燃烧系统可操作性的方法。这种系统用于空间加热，发电和其他工业应用。本研究对这一概念进行了进一步的探讨。

The objectives of this study are (1) to characterize experimentally stretched, lean, premixed flames under laminar and mildly turbulent conditions using particle thermometry and laser-induced fluorescence; (2) to assess enhancement of flame stability and lean-burning limits in premixed hydrocarbon (methane or propane) flames by addition of hydrogen or hydrogen/carbon monoxide mixtures; (3) to develop and validate reduced mechanisms to predict flame behavior (including extinction) of methane/ hydrogen/ carbon monoxide fuel mixtures; and (4) to develop analytical understanding of how multicomponent fuels with different Lewis numbers impact flame stability. The experimental studies and subsequent validation of numerical models rely detailed characterization of counterflow, opposed-jet, premixed flames. Independent variation of the hydrogen and carbon-monoxide concentrations in the fuel feed offer a new mean of exploring and influencing the chemical pathways in lean, premixed hydrocarbon combustion, in particular near extinction. To measure extinction conditions in the counterflow flames, flow fields are probed with laser Doppler velocimetry and temperature fields are measured by observing emissions from micron-size particles with a sensitive infrared camera. Laser-induced fluorescence (LIF) along the flame centerline probes flame structure through measurements of hydroxyl and formaldehyde fluorescence signals. Previous studies have shown that small amounts of hydrogen in the fuel stream can substantially extend the stability limits of stretched, premixed flames, suggesting that this may be a way to enhance the operability of lean, premixed, dry, low-NOx combustion systems. Such systems are used for space heating, power generation, and other industrial applications. This concept is further explored in this study.