Three-dimensional LES modeling of induced gas motion under the influence of injection pressure and ambient density in an ultrahigh-pressure diesel injector

Abstract

Detailed three-dimensional numerical simulations have been performed to analyze gas motion generated by dispersion of non-evaporating ultrahigh-pressure diesel spray. Fuel–air mixing is studied under different injection pressures and ambient densities, based on Eulerian–Lagrangian scheme. Large eddy simulation (LES) turbulence model along with an advanced primary breakup scheme have been applied to model the two-phase flow. The freeware code OpenFOAM is implemented to study the effects of the injection pressure and ambient density on gas motion. To evaluate the capability of the LES method in the simulation of gas motion in a high-pressure injection chamber, the obtained results were validated against published experimental data. Also, spray characteristics have been presented and induced gas velocities compared with experimental data. There are temporal variations in the gas movement around the spray. Based on the reported literature, gas velocity field around the spray is divided into three different zones: quasi static zone, gas recirculation zone, and head vortex zone. Accordingly, induced gas motions that are affected by the spray tip velocity are different in these areas. 3-D plots of spray liquid volume fraction and gas velocity vectors have also been presented. Overall, numerical results have displayed good agreement with the experimental data. It is concluded that LES is quite capable of reproducing the turbulent structures in gas field, mainly in ultrahigh-pressure injection.