Simulation Study on EGR Condensate Flow and Uniformity of Each Cylinder in the Intake Manifold

<div class="section abstract"><div class="htmlview paragraph">As engine technology developed continuously, engine with both turbocharging and EGR has been researched due to its benefit on improving the engine efficiency. Nevertheless, a technical issue has raised up while utilizing both turbocharging and EGR at the same time: excess condensed water existed in intake manifold which potentially trigger misfire conditions. In order to investigate the root-cause, a CFD model (conducted by CONVERGE CFD software) was presented and studied in this paper which virtually regenerated intake manifold flow-field with EGR condensed water inside. Based on the simulated results, it concluded that different initial conditions of EGR condensed water could significantly change the amount of water which deposited in each cylinder. Thus, a coefficient of variation of deposited condensed water amount among these cylinders, was marked as the evaluation reference of cylinder misfire. Theoretically, as this coefficient of variation reduced, the EGR condensed water from intake manifold would be distributed homogeneously in each cylinder, and thus less possibility of cylinder misfire should be observed. As concluded from the presented multiple simulated results, the coefficient of variation of deposited condensed water amount was above 30% statically for the existing intake manifold, which meant the existing intake manifold had tremendous room for optimization. The result showed that the fluctuation of the inner surface of the intake manifold had a great impact on the flow of condensate water, so different surface shapes could be designed in the intake manifold to organize the flow of condensate water, so as to make the condensate water of each cylinder more uniform, and reduce the occurrence of fire.</div></div>