Every passing year automotive engineers are challenged to attain higher fuel economy and improved emission targets. One widely used approach is to use Cooled Exhaust Gas Recirculation (CEGR) to meet these objectives. Apart from reducing emissions and improving fuel economy, CEGR also plays a significant role in knock mitigation in spark ignited gasoline engines.
Generally, CEGR is introduced into the intake manifold in SI gasoline engine. Even though the benefits of using CEGR are significant, they can be easily negated by the uneven CEGR flow distribution between the cylinders, which can result in combustion instability. This paper describes the application of co-simulation between one and three dimensional tools to accurately predict the distribution of CEGR to the cylinders and the effect of its distribution on engine performance. In order to understand the effect of uneven CEGR distribution on combustion and system performance, a three dimensional intake manifold model was used along with a one dimensional engine system model with a model developed in-house for knock prediction.
Two extreme scenarios for distribution of CEGR are considered for an SI engine, one with very low variation and one with very high variation between cylinders. This paper compares engine performance between these two cases and illustrates the importance of well distributed CEGR.