Laser Diagnostics of Soot Formation Processes in Diesel Spray Flame

By: Tetsuya Aizawa

28 February 2011

In order to develop clean next-generation diesel engines with ultra-low exhaust particulation emission, it is important to fully understand the soot formation processes occuring in the spray flame in the engine cylinder. The authors employed laser spectroscopy and imaging techniques to examine when and where the formation and growth of soot precursors occur in the diesel spray flame. The chemical composition and the growth processes of the soot precursors were further investigated by a newly-developted laser-spectroscopic technique called Excitation-Emission Matrix (EEM) using a multi-wavelength excitation laser source. The examination of diesel spray flame using the EEM technique revealed that the formation and growth of soot precursors can be delayed or suppressed by lowering the ambient temperatures and oxygen concentration in the cylinder.

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