Computational Fluid Dynamics Simulation of Diesel Engines with Sophisticated Injection Strategies for In-Cylinder Pollutant Controls

This work presents a computational fluid dynamics (CFD) methodology to simulate diesel combustion in high-pressure common-rail engines, which employ sophisticated injection strategies with rate shaping to reduce the in-cylinder pollutant formation and achieve the emission legislation EU6 and US Tier2 Bin 5. The physics of the mixture formation and its effects on combustion and, hence, on emission formation needs to be correctly described by the numerical tool. At the same time, in order to be used in a design and optimization stage of a new engine, the CFD methodology must be very efficient in terms of time requirements. For these purposes, the authors propose and assess the capabilities of the characteristic time-scale combustion model (CTC). The Shell autoignition model is used to predict autoignition, while the standard CTC model was improved by introducing a new expression to compute the characteristic time scale to be applied also in the presence of very high EGR rates. Soot emissions were predicted ...