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对层流和轻度湍流条件下拉伸、贫油、预混火焰进行实验表征;（2）评估预混碳氢化合物对火焰稳定性和贫油燃烧极限的增强作用（甲烷或丙烷）火焰，通过添加氢气或氢气/一氧化碳混合物;（3）开发和验证简化机制，以预测甲烷/氢气/一氧化碳燃料混合物的火焰行为（包括熄灭）;（4）开发对具有不同刘易斯数的多组分燃料如何影响火焰稳定性的分析理解。 数值模型的实验研究和随后的验证依赖于逆流、对向射流、预混火焰的详细表征。 燃料进料中的氢和一氧化碳浓度的独立变化提供了探索和影响贫预混烃燃烧中的化学途径的新手段，特别是接近熄灭的化学途径。 为了测量逆流火焰中的熄灭条件，用激光多普勒测速仪探测流场，用灵敏的红外相机观察微米级颗粒的排放来测量温度场。 沿着火焰中心线的激光诱导荧光（LIF）通过测量羟基和甲醛的荧光信号来探测火焰结构。 以前的研究表明，燃料流中的少量氢气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贫燃预混干式低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。 本研究进一步探讨了这一概念。

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.