Eulerian CFD modeling of nozzle geometry effects on ECN Sprays A and D: assessment and analysis

Diesel spray modeling is a multi-scale problem with complex interactions between different flow regions, that is, internal nozzle flow, near-nozzle region and developed spray, including evaporation and combustion. There are several modeling approaches that have proven particularly useful for some spray regions although they have struggled at other areas, while Eulerian modeling has shown promise in dealing with all characteristics at a reasonable computational effort for engineering calculations. In this work, the sigma -Y single-fluid diffuse-interface model, based on scale separation assumptions at high Reynolds and Weber numbers, is used to simulate the engine combustion network Sprays A and D within a Reynolds-averaged Navier-Stokes turbulence modeling approach. The study is divided into two parts. First of all, the larger diameter Spray D is modeled from the nozzle flow till evaporative spray conditions, obtaining successful prediction of numerous spray metrics, paying special attention to the near-nozzle region where spray dispersion and interfacial surface area can be validated against measurements conducted at the Advanced Photon Source at Argonne National Laboratory, including both the ultra-small-angle X-ray scattering and the X-ray radiography. Afterwards, an analysis of the modeling predictions is made in comparison with previous results obtained for Spray A, considering the nozzle geometry effects in the modeling behavior.