基于OH^(*)化学发光特性的CH4/O_(2)扩散火焰燃料稀释效应研究

Fuel Dilution Effect Based on OH^(*) Chemiluminescence in CH4/O_(2) Diffusion Flame

利用高分辨率相机成像系统获得了CO_(2)稀释的CH_(4)/O_(2)扩散火焰OH^(*)化学发光分布.揭示了不同稀释水平下OH^(*)层峰值特性以及外锋面半径的变化,并基于此探究了CO_(2)稀释燃料对火焰反应区和结构特性的影响.结果表明,OH^(*)化学发光峰值强度与CO_(2)稀释水平存在线性关系.当达到某一阈值稀释水平时,反应区从轴线处断开,火焰反应区分布形态的变化导致火焰高度迅速下降.随着稀释水平的提高,发生OH^(*)峰值的位移.OH^(*)表征的火焰外锋面可拟合为一段圆弧,拟合圆半径可用于表征火焰弯曲程度.随着稀释水平逐渐升高,火焰外锋面圆半径逐渐增大.

The OH^(*)chemiluminescence distributions of CO_(2)-diluted CH_(4)/O_(2)diffusion flame were obtained through a high-resolution camera imaging system.The peak properties of the OH^(*)layer and the changes of the outer front radius at different dilution levels were revealed.The influence of the CO_(2)dilution in fuel on the flame reaction zone and structural characteristics was further explored.The results show that there is a linear relationship between the peak intensity of OH^(*)chemiluminescence and the CO_(2)dilution level.When a certain threshold dilution level is reached,the reaction zone is disconnected from the axis,and the morphology change of flame reaction zone causes the rapid decrease of flame height.As the dilution level increases,a shift of the OH^(*)peak occurs.In addi-tion,the flame outer front indicated by OH^(*)can be fitted into a circular arc,and the degree of flame curvature can be the characterized by the radius of the fitted circle.With the gradual rise of the dilution level,the radius of the flame outer front gradually increases.