LARGE EDDY SIMULATION OF HIGH-VELOCITY FUEL SPRAYS: STUDYING MESH RESOLUTION AND BREAKUP MODEL EFFECTS FOR SPRAY A

Large eddy simulation (LES) of the nonreacting Spray A target conditions, as defined by the Engine Combustion Network, are carried out and compared to high-quality, experimental validation data. The investigated test case is characterized by a high injection pressure, small nozzle hole diameter, and inert ambient gas conditions at high-temperature and high-pressure. In the present study, implicit LES is used together with the Lagrangian particle tracking approach for the liquid phase to (i) investigate the effect of mesh resolution and (ii) study the influence of droplet breakup modeling on the local and global flow characteristics. Two breakup models are compared at four different mesh resolutions. The results are quantitatively analyzed with respect to integral spray quantities and validated against the experimental data. Qualitative characterization of the local velocities and mixture formation is presented. A good agreement of simulated and measured liquid/vapor penetration is achieved for both breakup models, given a sufficient mesh resolution. However, local differences in droplet diameter and vapor mass are observed between the breakup models in the nozzle vicinity. The overall mixture formation shows little dependency on the breakup modeling approach yet a strong dependency on the mesh resolution.