Numerical simulations of Diesel engine combustion by means of OpenFOAM CFD ToolBox

The present work is focused on multidimensional simulations of combustion in Diesel engines, using detailed kinetics reaction schemes. The selected reaction mechanism is the scheme developed by Liu et al. [1].The simulations are performed through the open source CFD Toolbox OpenFOAM (Open Field Operation and Manipulation). OpenFoam uses finite volume methods to solve systems of partial differential equations ascribed on any 3D unstructured mesh of polyhedral cells. A preliminary analysis relevant for diesel combustion studies is performed in constant volume homogeneous conditions. Here the treatment of the stiff ordinary differential equations arising from the usage of detailed kinetics reaction mechanisms and the performance of different solvers are investigated. The CVODE package has been integrated in OpenFOAM, as an alternative solver to the one provided by the original version of the code.

Then the predictive capabilities of the application available in the software for diesel engines combustion simulations are verified comparing computed pressure profiles with experimental data. The measurements are collected from a single cylinder Diesel engine with the same architecture of the real four-cylinder FIAT 1.9 litre Multi-Jet engine. The engine is fuelled with pure n-heptane, in order to allow the direct use of reaction mechanisms for a single-component fuel.