Spectroscopic investigation of the combustion process in an LPG lean-burn SI engine

摘要

Band spectrum images for CH, OH and CHO were taken in a heavy-duty-type LPG lean-burn SI engine, to investigate the combustion process as it pertains to the pollutant formation process in the post flame region. Full spectra and band spectrum flame images were observed with a bottom-view, single-cylinder research engine and two high-speed cameras. NO_x emissions were also measured for excess air ratios ranging from 1.0 to 1.6. A thermodynamic model, including the detailed chemical kinetic mechanism for LPG and NO_x formation reactions, was developed to predict the major reaction species in the post flame region, and NO_x emissions during the combustion process. The model qualitatively described the flame images for each band spectrum and could predict the measured NO_x emissions very well.