Combustion of hydrogen-enriched methane in a lean premixed swirl-stabilized burner

The combustion characteristics of a premixed, swirl-stabilized flame were studied to determine the effects of enriching methane with hydrogen under fuel-lean conditions. The burner consisted of a center-body with an annular, premixed fuel-air jet. Swirl was introduced to the flow using 45-degree swirl vanes. The combustion occurred within an air-cooled quartz chamber at atmospheric pressure. Flame stability and blowout maps were obtained for different amounts of hydrogen addition at several fuel-air flow rates. Gas probe measurements were obtained to demonstrate reductions in GO concentration with hydrogen addition, without adversely affecting the NOx emissions. The flame structure near the lean stability limit was described by direct luminous photographs and planar laser-induced fluorescence measurements of the OH radical. Results show that the addition of a moderate amount of hydrogen to the methane/air mixture increased the peak OH concentration. Hydrogen addition resulted in a significant change in the flame structure, indicated by a shorter and more robust appearing flame. The observed trends concur with the strained opposed premixed flame analysis using RUN-1DL. The computations revealed that enriching the methane with hydrogen increased the strain resistance of the flame as well as the OH levels in the flame.