A Comparative Study on Flame Length Using Numerical Analysis and Flame Visualization in Premixed Combustion

One promising technology for reducing emissions is the ultra-low NOx combustion systems, which have recently achieved a remarkable reduction in NOx emissions to as low as 7 ppm through lean combustion techniques. However, a significant challenge remains in simultaneously reducing both NOx and CO emissions due to the inverse relationship exhibited by these two pollutants. Therefore, there is a need for a solution that can determine the flame shape to reduce the emissions of NOx and CO in premixed flames. In this paper, a comparative study using numerical analysis and flame visualization was conducted to predict flame length and shape. Numerical analysis was performed to study the flame shape. In the experiments, the actual flame shape was obtained using the flame visualization technique, that was achieved by applying optical filter in specifically highlighting the CH wavelength band. As comparative results between simulation and experiments, the simulation flame lengths were 30 mm for residual fuel fractions of 1%. In contrast, the flame visualization showed a flame length of 14 mm. Therefore, there was about twice the length difference between the actual flame visualization and the simulation flame.