Advanced CFD modeling of a diesel-like spray in reacting condition

Abstract

The aim of the present project is to study the turbulent combustion pro-cess in a diesel-like spray by means of CFD modeling. In order to do so a pre-existing unsteady flamelet / progress variable (UFPV) model based on the flamelet concept and pre-tabulated chemistry was used. The interaction between turbulence and chemistry was accounted for by means of the sta-tistical distribution of the main variables with presumed probability density function (PDF) modeling. Furthermore, the implementation of the core of the model, a Reynolds averaged Navier-Stoke (RANS) solver, was done in the CFD platform OpenFOAM. The application of this model to the spray considered in this work, namely “Spray A” defined by the Engine Combustion Network (ECN), had as objec-tive the study of the transient and stationary flame structure. First, a model validation by comparing numerical and experimental values for ignition de-lay and lift-o˙ length was undergone. Afterwards the inner flame structure was analysed during auto-ignition sequence and steady state by means of temperature and species distributions in physical coordinates as well as in intrinsic combustion coordinates. Finally two parametric studies over model parameters ˙ and the synchronisation approach were carried out. On the one hand these studies had the aim of testing the robustness of the model when variations over the original one were made. On the other, the sensitivity of the model to these perturbations was tested in order to address their validity as adjustment parameters to the experimental data.