Validation of the VSB2 Spray Model against Spray A and Spray H

The modeling of spray breakup and evaporation is very complex, and several different models have been developed to describe the physical processes involved in these phenomena. However, problems of grid dependence, instability, and tuning issues remain to be adressed. Because the processes governing the breakup of dense sprays close to the nozzle are not fully understood, breakup models must be tuned to correctly predict vapor and liquid penetration, mixture fractions and their variances, droplet sizes, and so on. This work presents the Volvo Stochastic Blob and Bubble (VSB2) spray model and describes its performance in simulations of sprays A and H from the Engine Combustion Network (ECN). The predicted vapor penetration, liquid penetration, mixture fractions, and turbulence characteristics obtained using different computational grids and various simulated ambient conditions were analyzed. The VSB2 spray model accurately reproduced the experimental data for both sprays and correctly predicted their vapor and liquid penetration under various ambient conditions. The results demonstrate the importance of properly resolving the flow field. In addition, issues relating to spray modeling in general are discussed.