Search Results

Automated mechanism reduction is important in enabling the use of kinetics data in engineering design. In this work, we report on a mechanism-reduction technique that serves as a practical tool for automated mechanism reduction when applied to engine-simulation, with particular focus on compression-ignition engines. For this application, a multi-zone engine model has been developed, which can capture the stratification in the engine due to crevice and boundary-layer cooling effects. The multi-zone model serves as the workhorse for the mechanism-reduction algorithm. The reduction process is designed to operate on model-solution data from a parametric matrix of runs, in which the multi-zone model is run under different conditions. A more accurate reduction can therefore be achieved while accounting for spatial variations in the engine, temporal variations over the compression cycle, and variations in operating conditions.

While gasoline surrogate development has progressed in the areas of more complex surrogate mixtures and in kinetic modeling tools and mechanism development, it is generally recognized that further development is still needed. This paper represents a small step in supporting this development by providing comparisons between experimental engine data and surrogate-based kinetic models. In our case, the HCCI engine data comes from a port-injected, single-cylinder research engine with intake-air heating for combustion phasing control. Timing sweeps were run at constant fuel rate for three market gasolines and five surrogate mixtures. Modeling was done using the CHEMKIN software with a gasoline mechanism set containing 1440 species and 6572 reactions. Five pure compounds were selected for the surrogate blends and include iso-octane, n-heptane, toluene, methylcyclohexane, and 1-hexene.