Study on the Effects of EGR Supply Configuration on Cylinder-to-Cylinder Dispersion and Engine Performance Using 1D-3D Co-Simulation

摘要

Exhaust Gas Recirculation (EGR) is widely used in IC combustion engines for diluting air intake charge and controlling NO_x emission. The rate of EGR required by an engine varies by the speed and load and control of the right amount entering the cylinders is crucial to ensure good engine performance and low NO_x emission. However, controlling the amount of EGR entering the intake manifold does not ensure that EGR rate will be evenly distributed among the engine's cylinders. This can many times lead to cylinders operating at very high or low EGR rates which contradictory can deteriorate particulate matter and NO_x emission. The present study analyses the cylinder-to-cylinder EGR dispersion of a 4 cylinder 2.2L EUROV Diesel engine and its effects on the combustion stability. A 1D-3D coupling simulation is performed using GT-Power and STAR-CCM+ to analyze the effects of intake manifold geometry and EGR supply configuration on the EGR homogeneity and cylinder-to-cylinder distribution. The results confirm that the EGR supply configuration plays a key role on the intake air charge homogeneity and as a result to the EGR cylinder-to-cylinder distribution and combustion stability. The turbulence flow created at the point of EGR diffusion was found to be the governing factor influencing the performance of an EGR mixer. Small air-EGR “contact” areas, Venturi shape and high pressure differences contribute towards the increase of turbulence kinetic energy at the EGR injection area.