富氧条件下乙醇喷雾燃烧特性的实验研究

Experimental study on ethanol spray combustion characteristics under oxy-fuel conditions

利用McKenna型平面火焰燃烧器搭建乙醇喷雾燃烧实验台架,研究富氧条件下乙醇喷雾的燃烧特性.通过数字图像处理技术提取喷雾火焰特征参数和CH*自由基分布特征参数.其中,火焰特征参数包括火焰面积、火焰高度、火焰平均亮度.分析伴流气体O_2浓度、伴流气体CO_2浓度、乙醇与雾化N_2质量流量比对喷雾火焰特性及CH*自由基分布特性的影响.研究表明,在O_2浓度为21%~55%时,随着O_2浓度的增加,火焰高度和火焰面积均呈降低趋势,而火焰平均亮度呈升高趋势.通过对CH*自由基分布特性的分析发现,O_2浓度越高,燃烧反应区域的分布范围越小,反应强度越大.CO_2浓度对喷雾火焰尺寸与火焰平均亮度的影响与O_2浓度的影响相反,并且CO_2浓度对喷雾火焰平均亮度的影响明显大于其对喷雾火焰尺寸的影响.随着乙醇与雾化N_2质量流量比的增加,火焰尺寸及燃烧反应强度均呈显著升高趋势.

The combustion characteristics of ethanol spray under oxy-fuel conditions were investigated in the spray combustion test rig conducted using a McKenna flat flame burner.The flame feature parameters and CH*free radical distribution feature parameters were extracted based on image processing technology.The flame height,flame area and flame average brightness were proposed to characterize the flame features.The study focused on the effect of O2 concentration,CO2 concentration and ethanol/N2 mass flow rate ratio on spray flame and CH*free radical distribution characteristics.Results show that,in the O2 concentration range of 21%to 55%,the flame height and the flame area both decrease with the increase of O2 concentration on while the flame average brightness shows the opposite tendency.Higher O2 concentration leads to smaller reaction distribution region and higher combustion intensity according to the CH*radical distribution characteristics.The effect of CO2 concentration on flame size and flame average brightness is opposite to that of O2 concentration,and the effect of CO2 concentration on flame average brightness is more remarkable than that on flame size.In addition,the increasing trends of flame size and combustion intensity are observed with increasing ethanol/N2 mass flow rate ratio.