Laser extinction technique for measurements of carbon particles concentration during combustion

Particulate matter (PM) from diesel engines originate from soot particles which form during combustion and is notoriously a major source of concern as an airborne contaminant in the environment. The mechanisms by which soot is generated in diesel engines are still not completely understood and the use of optical techniques in a controllable environment is crucial for this purpose. This work focuses on the development and application of the laser extinction technique to the study of soot formation evolution in a rapid compression machine (RCM). A suitable optical arrangement to determine soot kinetics with high temporal resolution is presented together with the results obtained in the case of rich n-heptane, toluene and toluene/n-heptane mixtures under different conditions of pressure and temperature. The experimental investigation is focused on the fuel-rich premixed turbulent flame.

► An optical setup for measurements of soot formation in a rapid compression machine is proposed.
► Toluene/n-heptane mixtures with different toluene proportions are investigated.
► Tracking of soot concentration evolution with a time resolution of 10 μs is performed.
► The setup allows the study of soot formation is in the nucleation phase.