Optical analysis of homogeneous charge compression ignition combustion

In this study, we applied luminous spectroscopic analysis and Planar Laser Induced Fluorescence (PLIF) method on lean Homogeneous Charge Compression Ignition (HCCI) combustion to obtain some ideas of ignition timing control and combustion rate control methods in HCCI engines. In the tests, we used an optical access engine and n-C₁₂H₂₆ as a fuel. Inlet air temperatures and inlet oxygen concentrations were changed as the test parameters, and the following conclusions were obtained: (1) After low temperature reaction, LIF signal from hydrocarbon was disappeared. This was because that hydrocarbon was changed to another molecules or per oxides. (2) In high temperature reaction region, OH radical was appeared across a wide area in the combustion chamber.