An Investigation of Different Ported Fuel Injection Strategies in HCCI Engines Using Chemiluminescence Imaging

摘要

The purpose of this study was to gain a better understanding of the effects of ported fuel injection strategies on the HCCI combustion processes. Experiments were conducted in a single-cylinder HCCI engine modified with windows in the combustion chamber for optical access. Two-dimensional images of the chemiluminescence were captured by using an intensified CCD camera in order to understand the spatial distribution of the combustion. N-heptane was used as a test fuel. The results of cylinder pressure, heat release rate, chemiluminescence images all indicate that the different ported injection strategies result in the different charge distribution in the combustion chamber, and thus affect the auto-ignition timing, chemiluminescence intensity, and combustion processes. Under the higher intake temperature condition, the injection strategies have less effect on the combustion processes due to the improved mixing. The injection during intake stroke and intake valve opening phase (-300 °ATDC) results in more homogeneous charge mixing, which will be benefit to the combustion control and fuel economy.