Local A/F Measurement by Chemiluminescence OH*, CH* and C2* in SI Engine

The chemiluminescence emission intensity can be measured with high temporal resolution, leading to understanding the chemical reaction. Time-series chemiluminescence measurements of OH*, CH* and C₂* were carried out to understand flame propagation speed, its thickness and A/F ratio of combustion status. The optical piston head (quartz) allows us to visualize combustion chamber. It is found that the chemiluminescence intensity ratio of CH*/OH* and C₂*/OH* can estimate local A/F. The A/F measured by O₂ sensor was used for evaluation and the results indicate this method can be applicable to estimate A/F.