碳氢扩散火焰实验研究:燃烧气氛对火焰光谱与温度的影响

Experimental Investigation on Hydrocarbon Diffusion Flames:Effects of Combustion Atmospheres on Flame Spectrum and Temperature

辐射是各种燃烧过程中热传递的主要方式。在不同的火焰中,辐射光谱分布十分复杂。在这项工作中,利用光谱仪测量了可见光(200~900nm),近红外(900~1700nm)和中红外(2500~5000nm)波段火焰的光谱强度,分析了空气和富氧气氛下扩散火焰的光谱特征。并基于光谱分析,定量得到了火焰中碳烟以及气体发射的辐射力,计算了火焰的温度分布。结果表明,空气燃烧中的火焰温度低于富氧燃烧中的火焰温度。在空气气氛下,火焰中的碳烟和气体均对中的热辐射起着重要作用。而在富氧气氛下,气体对于火焰热辐射更为重要。在可见光和近红外波段,由于在空气气氛下火焰中碳烟的大量形成,光谱曲线显示出了良好连续性。而富氧气氛下火焰的辐射光谱降低。在中红外波段,空气气氛下火焰的气体辐射明显弱于富氧气氛下火焰的气体辐射。

Radiative heat transfer is the main mode of heat transfer in various combustion processes.The distribution of radiative spectra is complicated for different flames.In this work,the spectral intensities of a hydrocarbon diffusion flame invisible(200~900 nm),near-infrared(900~1700 nm)and middle-infrared(2500~5000 nm)wavebands were measured by spectrometers.The spectral characteristics of the flame in air and oxy-combustion atmospheres were analysed.Based on spectral analysis,flame temperature was calculated,and thermal radiation from soot particle and gases in the flame could be quantitively evaluated.The results show that flame temperature in air combustion is lower than in oxy-combustion.Both soot and gas in flames play an important role in thermal radiation in air combustion,and gas is more important for thermal radiation in oxy-combustion.In visible and near-infrared wavebands,the spectral curve shows good continuity in air-combustion due to soot formation,but the radiative spectrum reduces in oxy-combustion.In the midinfrared waveband,the gas radiation spectrum of air-combustion is obviously weaker than that of oxycombustion.