EGR Mixer Optimization for Equal EGR Distribution to each Cylinder using 1D-3D CFD Coupled Simulation 2020-28-0390
Vehicles are main source of pollution contributor, producing substantial amounts of pollutants. Pollution causes the health problems, hence Emission legislations are becoming increasingly strict all over the world moving from Trem IIIA to Stage V for Off-highway vehicles. EGR has been successfully proved as a useful technology to reduce NOx by decreasing the oxygen concentration and the peak temperature of the combustion. Due to compact design and space restriction, the distance required for the homogeneous mixing of fresh air and EGR is not enough. Therefore the mixing of the EGR and distribution of the EGR over the cylinders is not equal. This non uniform mixing of the EGR and the fresh air leads to increase in the NOx and soot compared to the homogeneous mixture due to lower combustion efficiency.
1D simulations are used for system level studies due to benefits of less simulation time and more information at system level but 1D simulations cannot model accurately the 3D dynamics at component level. 3D flow dynamics of EGR mixing and distribution cannot be analyzed with 1D modelling only. 3D CFD simulations are useful for component level studies due to detail modelling. But 3D CFD cannot be used for EGR mixing due to different boundary conditions in the actual engine operation, also 3D CFD requires more simulation time. So, to balance between the advantages and disadvantages of the 1D and 3D, a 1D – 3D coupled simulation approach is used. In 1D – 3D coupled simulation, complex flow components are modelled in 3D and the rest of the components are modelled in 1D.
In this paper, intake manifold and EGR mixer is optimized for uniform distribution of EGR over the cylinders meeting the targets of intake manifold pressured drop, simple design for manufacturing and engine performance. 1D software GT power and 3D CFD software Converge-Lite is used for coupling. This study is carried out for 4 cylinder turbocharged Trem IIIA engine which is being developed for Stage V emission norms for off-highway applications.1D-3D CFD coupling is used to study the EGR distribution over the cylinders.