A Study of HCCI Combustion Using In-Cylinder Flame Visualization and Ultraviolet Absorption Spectroscopy (Understanding the Rapid HCCI Combustion by Observing the In-Cylinder Flame Behavior)

Abstract

This study investigated the characteristics of the HCCI combustion process in detail by means of in-cylinder visualization of the entire bore area and ultraviolet absorption spectroscopic measurement in the combustion chamber. Special attention was focused on the influence of the equivalence ratio and ignition timing on the degree of local dispersion of autoignition and resultant rapid combustion. The results made clear the relationship between the production/consumption of formaldehyde (HCHO) in the autoignition process and flame development behavior in the combustion chamber. Additionally, it was found that changes in the equivalence ratio and/or ignition timing significantly influenced the degree of local dispersion of the autoignited flame in the combustion chamber. As a result, some cases showed rapid combustion accompanied by in-cylinder pressure oscillations.