CO_(2)稀释对甲烷反扩散火焰结构的影响研究

Effects of CO_(2) dilution on the structure of methane inverse diffusion flame

基于火焰光谱诊断平台,利用由高分辨率CCD相机成像系统和光纤光谱仪组成的光谱成像系统对甲烷反扩散火焰的光谱辐射特性进行研究。获得了不同氧燃当量比和CO_(2)稀释水平下CH4/O_(2)同轴射流反扩散火焰的OH^(*)、CH^(*)二维辐射分布并进行了Abel反卷积处理。结果表明:随氧燃当量比的增加,OH^(*)火焰逐渐中空,火焰锋面被拉伸,轴向高度和火焰面积均先增大后减小。CH^(*)火焰核心反应区位置和形状随当量比增加变化不明显。随CO_(2)稀释剂体积分数的增加,OH^(*)火焰被拉伸,并由完全包络状过渡为对称包络状,火焰面积逐渐减小。CH^(*)火焰被拉伸并靠近中央轴线,火焰面积逐渐增大。对比OH^(*)火焰层,CH^(*)火焰层较薄且峰值强度低。

Based on the flame spectrum diagnostic platform,a spectral imaging system composed of a high-resolution CCD camera imaging system and a fiber optic spectrometer is used to study the spectral radiation characteristics of the methane inverse diffusion flame.The OH^(*)and CH^(*)two-dimensional radiation distributions of the IDF with various oxygen-fuel equivalence ratios and CO_(2) dilution levels were obtained by the flame spectrum imaging system.The OH^(*)and CH^(*)emission data was deconvoluted by using an inverse Abel transform to analyze flame structure.The results show that the OH^(*)flame gradually became hollow,the flame front was stretched,and the axial height and flame area both increased first and then decreased with the increase of the oxygen-to-fuel equivalence ratio.The position and shape of the CH^(*)flame core reaction zone was unchanged significantly with the change of the equivalence ratio.The OH^(*)flame was stretched and transformed from a completely enveloped shape to a symmetrical envelope shape with the increase of the CO_(2) diluent volume fraction in the oxidant.The CH^(*)flame was stretched closer to the central axis.The OH^(*)flame area decreased and the CH^(*)flame area increased due to the influence of CO_(2) dilution.Compared with the OH^(*)flame layer,the CH^(*)flame layer was thinner and the peak intensity was low.