3D Large Scale Simulation of the High Speed Liquid Jet Atomization

In this paper three-dimensional Large Eddy Simulations (i.e., LES) by using a PLIC-VOF method have been adopted to investigate the atomization process of round liquid jets issuing from automotive multi-hole injector-like nozzles. LES method is used to compute directly the effect of the large flow structure, being the smallest one modelled. A mesh having a cell size of 4 μm was used in order to derive a statistics of the detached liquid structures, i.e. droplets and ligaments. The latter have been identified by using an algorithm coded by authors. Cavitation modeling has not been included in the present computations. Two different mean injection nozzle flow velocities of 50 m/s and 270 m/s, corresponding to two mean nozzle flow Reynolds numbers of 1600 and 8700, respectively, have been considered in the calculations as representative of laminar and turbulent nozzle flow conditions. The numerical results clearify the role of both the boundary layer relaxation and the inner liquid jet turbulence in determining the onset of jet surface perturbations. Simulations indicate that, at the high Oh and We numbers typical of automotive injection conditions, the nozzle flow regime likely determines the same statistics of the detached liquid structures, while it changes the fragmentation rate of the liquid jet considerably.