Browse Publications Technical Papers 2010-01-0359

The Effects of Injection Timing and Piston Bowl Shape on PHCCI Combustion with Split injections 2010-01-0359

To reduce diesel engine emissions, a split injection strategy with PHCCI combustion in a diesel engine was investigated with simulation. A multidimensional CFD application, Star-CD coupled with a modified 2-D flamelet was used to simulate multiple injection combustion. Several mass ratios of the first injection and second injection conditions compared to the conventional pilot and main injection strategy were evaluated. The injection angle and the injection timing of the first injection were fixed to 150° and 55° BTDC, respectively. Because of the early injection, the in-cylinder pressure and temperature were much lower than those of normal injection conditions, and the fuel could not fully evaporate. As a result, wall impingement can be occurred, and THC and CO would be increased. To eliminate the wall impingement, the injection timing of the first injection was then retarded to 35-30° BTDC, and the piston bowl geometry was modified to capture droplets in the piston bowl. Subsequently, NOx and soot were reduced substantially. Finally, the piston bowl shape was modified again for spray re-entrance. In these results, NOx and soot were significantly reduced in all split conditions. The modified piston bowl shape was produced and validated in the engine experiment.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 40% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.