Detailed Analysis of Mixture and Combustion of Diesel Jets by Laser Induced Fluorescence Techniques

The evolution of Diesel engines in the last decades has been driven by the stringent pollution legislation and increasing environmental concern. In this context the Diesel engine appears like a very good candidate due to its naturally high efficiency. However, in order to further reduce engine out pollutant and green house gases to the required limits, a detailed study of the fuel-air mixing and combustion processes is necessary. An investigation of those processes by Laser Induced Fluorescence (LIF) techniques is presented. The mixing process is studied by tracer LIF, enabling a statistical analysis of the mixture structure and of the effect of injection parameters. The combustion process is studied by simultaneous formaldehyde, Poly-Aromatic-Hydrocarbons (PAH) and OH LIF, giving access to detailed information on the combustion process. A strong coupling is observed between the two processes.