富氧气氛下碳氢燃料同轴射流扩散火焰的形态特性

Morphology Characteristics of Hydrocarbon Fuels Coflow Jet Diffusion Flame under Oxygen-enriched Atmosphere

采用碳氢燃料燃烧实验台,在不同燃料流量和氧浓度下研究甲烷、乙烯同轴射流扩散火焰的火焰形态和温度变化,利用场发射扫描电镜观测不同位置的碳黑样本.结果表明,氧浓度由21%(φ)升至100%(φ)时,甲烷、乙烯火焰高度下降79%,火焰边缘温度比中心温度分别高233.6和337.3℃,乙烯外焰的腰部位置出现"黄金区域".乙烯流量增至170 m L/min、氧浓度增至31%(φ)时,火焰尖端出现"焰翅",而甲烷火焰始终未见"焰翅".在乙烯火焰"黄金区域"大量积聚的碳黑颗粒具有很高的发射率,火焰亮度明显增强.

The flame morphology and temperature variation of methane and ethylene cofiow jet diffusion flame at different fuel flow and oxygen concentration were studied on a hydrocarbon fuel combustion apparatus, and the soot samples at different positions in the flame were observed by field emission scanning electron microscope. The results showed that the oxygen concentration increased from 21%（φ） to 100%（φ）, the flame height of methane and ethylene decreased by 79%, and the flame edge temperature was higher than the central temperature 233.6 and 337.3 ℃, respectively. In the waist of the outer flame of ethylene appears ＂golden area＂, when the ethylene flow rate increased to 170 mL/min and oxygen concentration increased to 31%（φ）, the flame tip appeared ＂flame wing＂, while the methane flame did not see ＂flame wing＂ at all. The large accumulation of soot particles in the ＂golden area＂ of the ethylene flame has a high emissivity, and thus the flame brightness is significantly enhanced.