Implementation and Validation of a n-Heptane Kinetic Combustion Model for 3D-CFD Codes by Means of Numerical Calculations and Single Cylinder Engine Experiments

An integrated numerical-experimental research activity has been carried out, in order to investigate the reliability of a modified, parallel version of KIVA3V, coupled with detailed kinetics, as an additional tool for the analysis of experimental results. In the proposed approach, fixed chemical species included in the reaction mechanism are used as markers for selection of the numerical methods to be used, aiming at exploiting, in every phase of the calculation, the most suitable solver.

For validation purposes, pure n-Heptane was chosen as representative fuel model, both in experiments and computations. Calculated values are compared with experimental data collected on a single-cylinder diesel engine fuelled with pure n-heptane, in order to allow the direct use of a reaction mechanism for a single-component fuel. The single-cylinder research diesel engine employed in the work has the same architecture of a four-cylinder automotive engine currently on production, the FIAT 1.9 litre Multi-Jet engine. The selected reaction mechanism is the scheme developed by Liu et al. [1]. The measures are collected varying both the operative conditions and the engine compression ratio. The comparison between results from the simulations and measured data shows a very good agreement for conventional combustion conditions, confirming the model capability of capturing the CI combustion process behavior. Less accurate results are obtained in low temperature autoignition process simulations.