Abstract
4-stage-injection consisted of pilot-, pre-, main-, and after-injection was applied to a single cylinder direct injection heavy duty diesel engine to achieve lower emission under the condition of diffusive combustion. Soot suppression mechanism of 4-stage-injection was investigated using a 3D-CFD calculation. Since separately injected fuel effectively use oxygen unused for the main combustion, pilot- and pre-injection generates no soot and soot from after-injection is oxidized rapidly. Lower soot is formed from less main-injected fuel when 4-stage-injection is applied. These two effects provide reduction of soot emission.
