Optimizing EGR and Air Mixing Uniformity in Intake Manifold through CFD Simulations

Mingbo Cao

doi:10.54097/80y90793

Authors

Mingbo Cao

DOI:

https://doi.org/10.54097/80y90793

Keywords:

Exhaust Gas Recirculation (EGR); Intake manifold; Mixing uniformity; Computational Fluid Dynamics (CFD); Engine emission reduction.

Abstract

Optimizing exhaust gas recirculation (EGR) mixing in the intake manifold is a crucial step for reducing nitrogen oxides (NOx) emissions in multi-cylinder engines while maintaining combustion stability. In this study, the computational fluid dynamics (CFD) method was used to systematically evaluate the impact of EGR introduction strategies (injection position, angle, and EGR ratio) on the uniformity of EGR and air mixing in the intake manifold of a four-cylinder engine. The results show key trade-off relationships and design principles. With a higher EGR ratio, distribution uniformity improves, but local mixing quality degrades. EGR introduction should be placed far from the plenum, as a longer flow path can enhance turbulent dispersion. Most notably, an against-flow injection has a significant impact on mixing. Compared with the vertical-flow and the co-flow, EGR can mix more thoroughly with air using against-flow injection. These research findings provide practical and feasible insights for designing efficient exhaust gas recirculation systems. The overall optimization approach is highlighted in the future EGR system design process (optimizing the injection strategy alongside different intake manifold structures).

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