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TOWARD A THREE-DIMENSIONAL CFD MODEL FOR HCCI COMBUSTION IN DIESEL ENGINES

With the aim of simulating homogeneous charge compression ignition (HCCI) combustion the three-dimensional computational fluid dynamics (CFD) model AIM2Z is presented. AIM2Z allows for the fact that a mixture is not necessarily homogeneous at the subgrid-scale level. In each cell this model distinguishes a zone where fuel and air are not yet mixed from a zone where turbulence yields a mixture that is assumed to first order to be homogeneous. It is only in the latter zone that chemical kinetics—in the form of reduced schemes to limit CPU time in three-dimensional CFD applications—are applied. After the description of the model formulation, we evaluate a simple kinetic scheme for autoignition of n-heptane and iso-octane mixtures. Then basic implementation tests on simple diesel engine configurations are presented: a homogeneous case and a stratified case with liquid injection are simulated with AIM2Z and the simple scheme. They demonstrate the feasibility of AIM2Z and its a priori satisfactory behavior in an engine environment.