In-Cylinder Mechanisms of Soot Reduction by Close-Coupled Post-Injections as Revealed by Imaging of Soot Luminosity and Planar Laser-Induced Soot Incandescence in a Heavy-Duty Diesel Engine

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In-Cylinder Mechanisms of Soot Reduction by Close-Coupled Post-Injections as Revealed by Imaging of Soot Luminosity and Planar Laser-Induced Soot Incandescence in a Heavy-Duty Diesel Engine

O'Connor, Jacqueline / Musculus, Mark

Post injections have been shown to reduce engine-out soot emissions in a variety of engine architectures and at a range of operating points. In this study, measurements of the engine-out soot from a heavy-duty optical diesel engine have conclusively shown that interaction between the post-injection jet and soot from the main injection must be, at least in part, responsible for the reduction in engine-out soot. Extensive measurements of the spatial and temporal evolution of soot using high-speed imaging of soot natural luminosity (soot-NL) and planar-laser induced incandescence of soot (soot-PLII) at four vertical elevations in the piston bowl at a range of crank angle timings provide definitive optical evidence of these interactions.The soot-PLII images provide some of the most conclusive evidence to date that the addition of a post injection dramatically changes the topology and quantity of in-cylinder soot. As the post jet penetrates toward the bowl wall, it carves out regions from the main-injection soot structures, either through displacement of the soot or through rapid and progressive oxidation of the soot. Later in the cycle, the regions of main-injection soot on either side of the jet centerline, clearly present in the main-injection-only case, have all but disappeared when the post-injection is added - only the soot in the post-injection pathway remains. Evidence of this apparent late-cycle oxidation of main-injection soot appears in both the soot-PLII and soot-NL images, providing substantial support for the mixing mechanism of soot reduction with post injections. Implications of these findings and future work are also discussed.

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Title :

In-Cylinder Mechanisms of Soot Reduction by Close-Coupled Post-Injections as Revealed by Imaging of Soot Luminosity and Planar Laser-Induced Soot Incandescence in a Heavy-Duty Diesel Engine

Additional title:

Sae Int. J. Engines

Contributors:

O'Connor, Jacqueline (author) / Musculus, Mark (author)

Conference:

SAE 2014 World Congress & Exhibition ; 2014

Published in:

Sae International Journal of Engines ; 7 , 2 ; 673-693

Publication date :

2014-04-01

Size :

21 pages