Combined WAVE-VECTIS simulation of an intake manifold of V6 PFI gasoline engine

This paper describes the analysis of the flow in the intake manifold of a V6 gasoline engine performed using WAVE 1D engine cycle simulation program alone first, and then using WAVE coupled with 3D CFD VECTIS. The work shows how modeling in 3D selected components of the inlet manifold embedded within the 1D flow network leads to improvements in prediction accuracy.
The main purpose of this work was to improve the WAVE model of the V6 3.2l engine, scheduled for installation in the GTA version of the popular Alfa Romeo 156 vehicle. Moreover, this work was also part of a comparative study between two intake manifolds differing in shape and volume.
Whilst the performance of an engine is typically investigated using the 1D engine cycle simulation program WAVE alone, for this application the authors believe that only the use of the 3D CFD code VECTIS coupled with WAVE can accurately capture how the manifold influences the behaviour of the engine.
The WAVE model of this engine was derived from the V6 3.0l engine model which powers the Alfa Romeo 166 vehicle.
The use of the 3D mesh has been limited to specific components of the intake system that are likely to generate a very complex, 3D flow. This allows to minimize the unavoidable increase in runtime associated with CFD. The calculation provided interesting engine performance results (such as overall and individual cylinder volumetric efficiency, mass flow rate and power) when compared with the WAVE simulation alone, and very useful insights into the 3D flow patterns inside the intake system.

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