A comparison of diesel sprays CFD modeling approaches: DDM versus Sigma-Y Eulerian atomization model

Abstract

[EN] A comparison between the Σ-Y atomization model and a classical DDM approach has been carried out for diesel spray CFD simulations. The Σ-Y model, originally proposed by Vallet and Borghi (1999), is based on an Eulerian representation of the spray atomization and dispersion by means of a single-fluid variable density turbulent flow. The locally homogeneous flow approach has been applied in order to develop a spray vaporization model based on state relationships. A finite-volume solver for model equations has been created using the OpenFOAM CFD open-source C++ library (GarcíaOliver et al., 2013). In the case of the Lagrangian-DDM approach, the original dieselFoam solver of OpenFOAM is used. Model predictions have been compared to experimental measurements of free diesel sprays under vaporizing conditions from the database of the Engine Combustion Network (ECN). Accurate predictions of liquid and vapor spray penetration, as well as mixture fraction can be achieved for the nominal condition with both models, although DDM simulations tend to be less accurate. Additionally, near nozzle flow structure of the Spray A condition of ECN is also studied with both models. The conclusion is a more accurate prediction of the near-field internal structure of the spray in the case of the Eulerian model, due to both a higher mesh resolution and a more adequate modelling approach. Consequently, results shown in this work put in evidence the benefits of using an Eulerian model to predict qualitatively and accurately the diesel spray behaviour under different ambient conditions and injection pressures.