Flow Characteristics Of A Two-Dimensional Diffuser Of Catalytic Converters Situated Close To Engines Using Simulation

A close-coupled catalytic converter is placed close to the engine to efficiently treat harmful exhaust gases during warm up. The engine exhaust obliquely enters the diffuser upstream of the catalyst monolith through an inclined inlet pipe in which affects the degree of flow separation in the diffuser as well as the conversion efficiency of the after-treatment system. With reliable mathematical models, the effect of the inlet pipe geometry can be evaluated prior to expensive manufacture and testing. The main objective of this research is to predict the steady-state oblique entry flow in the diffuser upstream of the monolith using computational fluid dynamics (CFD) alongside the flow maldistibution across the monolith. The CFD domains were simplified as planar systems to capture the internal flow through the converter. The monolith was represented as a porous medium whereas the resistance was measured with uniform air flow being presented at the front face of the monolith. The predictions were performed at steady state using Reynolds Averaged Navier-Stokes (RANS) equations at a range of Reynolds numbers (provide the value range). The results show a formation of an oblique entry jet traversing the diffuser along with a large recirculation. With respect to the velocity profile across the monolith, the maximum velocities can be observed at the region where the monolith being hit by the jet