CO₂物理作用对甲烷扩散火焰燃烧特性影响
The Influence of CO₂ Physical Effects on the Combustion Characteristics of Methane Diffusion Flames

本文以天然气的烟气再循环技术为研究背景，主要研究CO₂气体的加入对CH₄/空气同轴射流层流扩散燃烧火焰影响。采用数值模拟方法，对CO₂气体的物理特性对火焰温度，CH₄反应速率峰值和火焰尺寸的影响分别进行分析，为深入研究CH₄火焰燃烧特性提供基础模拟理论的分析依据。研究结果显示，当空气中的部分N₂被CO₂代替后，火焰的燃烧温度会随着当量比的增加而降低，随着CO₂体积分数的增加而降低，并且无论是在贫燃料燃烧还是在富燃料燃烧，这种变化趋势保持一致。而CO₂的加入因其自身的高比重使得CO₂进入燃烧室后具有较大的分子动量，更有利于燃料与氧化剂混合发生反应，因此使得CH₄/空气反应速率的峰值升高，但并没有提高CH₄的燃烧效率。火焰尺寸不因CO₂的加入而发生变化，但随着当量比的增加而减小。
This study investigates the influence of CO？ addition on CH？/air coaxial jet laminar diffusion flames within the context of flue gas recirculation (FGR) technology for natural gas combustion. Numerical simulations were conducted to analyze the effects of CO？ physical properties on flame temperature, peak CH？ reaction rate, and flame dimensions, providing foundational theoretical insights for further research on CH？ flame combustion characteristics. Results indicate that substituting N？ in air with CO？ leads to a reduction in flame temperature, which decreases with both increasing equivalence ratio and CO？ volume fraction. This trend remains consistent under both fuel-lean and fuel-rich combustion conditions. The introduction of CO？ enhances the peak CH？ reaction rate due to its higher molecular momentum, which promotes fuel-oxidizer mixing. However, no significant improvement in CH？ combustion efficiency is observed. Flame dimensions remain unaffected by CO？ addition but decrease with increasing equivalence ratio.