Abstract
To characterize and model the combustion of a reactant mixture in a
spark-assisted compression ignition (SACI) engine, one-dimensional
reaction front propagation into end-gas mixtures with varying degrees of
reaction progress is simulated using a skeletal iso-octane mechanism
with variable transport properties. The dominant mechanism for the
end-gas auto-ignition and combustion is identified based on a ratio of
the corresponding flame to homogeneous ignition time scales, as a means
to distinguish the transport-controlled and chemistry-controlled
combustion regimes. The results indicate that reaction fronts
propagating into end-gases are deflagrative provided that the
temperature at the reaction front base is below 1100 K, while
beyond this temperature, transport has little effect on the
one-dimensional solution, indicating that reaction front propagation is
chemistry-controlled. The results suggest that reaction front combustion
regimes are strongly influenced by and can be separated with the
end-gas temperature at the base of the reaction front.