A Review of Turbulent Combustion Modeling for Multidimensional In-Cylinder CFD

Multidimensional computational fluid dynamics (CFD) has become an accepted and indispensible tool in the analysis and design of next-generation low-fuel-consumption, low-emissions internal combustion (IC) engines. Turbulent combustion models have been developed to deal with the wide variety of combustion phenomena that occur in spark- and compression-ignition, homogeneous- and stratified-charge engines. IC-engine combustion can vary from essentially premixed turbulent flame propagation, through turbulent-mixing-controlled nonpremixed combustion, to chemical-kinetics-controlled regimes, within a single device on a single engine cycle. In this review, an overview of the combustion systems of interest for reciprocating-piston IC engines is provided first. Then the underlying governing equations, and the manipulations and simplifications that lead to a tractable equation set suitable for engineering CFD calculations, are reviewed. Several turbulent combustion models are introduced in the context of multidimensional modeling case studies. The emphasis is on models that can accommodate multiple combustion regimes and detailed chemical kinetics; the coverage is not comprehensive. Strengths and shortcomings of current models are pointed out. The latter serve to provide direction for future research.