DIESEL ENGINE IN-CYLINDER CALCULATIONS WITH OPENFOAM

Abstract

The reduction of diesel engines emissions is a challenging task. Reducing both soot and NOx at the same time is quite difficult, especially with no fuel consumption penalty. Reducing them both is possible by enhancing the air-fuel mixing process in order to improve combustion. Experimental research still does not give us enough information about the very complex thermo-and fluid dynamic processes that are occurring in a diesel engine. In addition, experimental research is still quite expensive and time consuming. The objective of this work is to give support to experimental research by providing some insight into the complex phenomena that occur in the cylinder and the combustion chamber of diesel engines, using Computational Fluid Dynamics (CFD) modeling. The first task was to calculate the air flow through the inlet ports and cylinder of a diesel engine and the second one was to calculate combustion in a diesel engine. A steady flow test rig setup for diesel engine ports development has been successfully simulated with OpenFOAM (a free CFD software). The flow through the inlet ports was simulated at different valve lifts. The CFD calculated values of flow coefficients and swirl ratios agree fairly well with the experimental results. By sectioning the domain, a detailed description of the flow field can be obtained. A step forward was the simulation of combustion in a direct injection diesel engine. This is a much more complex task, but the calculated in-cylinder pressure corresponds to the measured pressure.