Atomization and Sprays, Vol.28, No.12, 1081-1100, 2018
NUMERICAL INVESTIGATION OF THE PRIMARY BREAKUP REGION OF HIGH-PRESSURE SPRAYS
The experimental limitations of the current diagnostics in the near-nozzle region of high-speed sprays led researchers to seek complementary information about the atomization process and the droplet formation from high-fidelity simulations. Detailed simulations can deliver crucial information of these complex processes to improve the global understanding as well as engineering models. We performed detailed simulations of the Engine Combustion Network Spray A case, an ideal target supported by an impressive experimental and numerical data set. An open source code solving the incompressible Navier-Stokes equations was used to investigate the stages of the atomization processes under the challenging conditions of high-pressure sprays. The simulations demonstrated mass conservation and reasonable agreement with the experiments for macroscopic parameters such as spray penetration and spray dispersion. Analysis of the simulation results showed that an unperturbed liquid region was observed in all simulated domains and grid spacing, extending several millimeters downstream of the nozzle exit. Information on droplet size was extracted and compared to experimental data from optical microscopy, but despite good agreement with the experiments for a specific numerical resolution, the distributions showed that grid size convergence was not achieved for the present simulations. The analysis of the results supports that highly detailed computations are needed to understand droplet formation, and confirm that the conditions of modern diesel injection processes represent a highly challenging problem to modelers.