An Investigation of the Effect of Charge Inhomogeneity on the Ignition and Combustion Processes in a HCCI Engine Using Chemiluminescence Imaging

Abstract

In the HCCI (Homogeneous Charge Compression Ignition) engines, inhomogeneity in fuel distribution and temperature in the pre-mixture exists microscopically and has possibility to affect the ignition and combustion process. In this study, the effect of charge inhomogeneity in fuel distribution on the HCCI combustion process was investigated. Pressure profiles were measured and two dimensional chemiluminescence images were captured by using a framing camera with a 4-stroke optically accessible engine in order to understand the spatial distribution of the combustion. DME (di-methyl ether) was used as the test fuel. By changing the way of mixing air and fuel in the intake manifold, inhomogeneity in fuel distribution in the pre-mixture was varied. The result shows that luminescence is observed in a very short time in a large part of the combustion chamber under the homogeneous condition, while luminescence appears locally with considerable time differences under the inhomogeneous condition. It is also shown that the local luminescence durations are almost the same under both conditions.

Keywords

• internal combustion engine
• premixed combustion
• hcci engine
• homogeneity
• di-methyl ether
• chemiluminescence
• radical