CO2 addition and pressure effects on laminarand turbulent lean premixed CH4 air flames

摘要

An experimental study on CH4–CO2–air flames at various pressures is conducted by using both laminarand turbulent Bunsen flame configurations. The aim of this research is to contribute to the characterizationof fuel lean methane/carbon dioxide/air premixed laminar and turbulent flames at different pressures, bystudying laminar and turbulent flame propagation velocities, the flame surface density and the instantaneousflame front wrinkling parameters. PREMIX computations and experimental results indicate adecrease of the laminar flame propagation velocities with increasing CO2 dilution rate. Instantaneous flameimages are obtained by Mie scattering tomography. The image analysis shows that although the height ofthe turbulent flame increases with the CO2 addition rate, the flame structure is quite similar. This impliesthat the flame wrinkling parameters and flame surface density are indifferent to the CO2 addition. However,the pressure increase has a drastic effect on both parameters. This is also confirmed by a fractal analysisof instantaneous images. It is also observed that the combustion intensity ST/SL increases both withpressure and the CO2 rate. Finally, the mean fuel consumption rate decreases with the CO2 addition ratebut increases with the pressure.