NO_x and NO₂ Emission of Swirl-Stabilized Nonpremixed Flames of a H₂—CH₄ Mixture

Abstract

NO_x emission levels and the NO₂/NO_x ratios were studied in swirl-stabilized H₂—CH₄ flames and comparison was made with H₂ flames under similar conditions (i.e. system parameters such as Reynolds and swirl numbers, and the recirculation zone residence time). Changing the fuel composition from 100% H₂ to 50% H₂—CH₄ was found to have moderate effects on the NO_x emission level. The NO₂/NO_x ratios with CH₄. substitution can be significantly higher than pure H₂ flames (about 80–95% for H₂—CH₄ flames, compared to 35–60% for H₂ flames), partly explaining its high values in practical gas turbine combustors.

Keywords:

• Nitrogen oxides
• swirl
• nonpremixed flame