ID 164

3D-Eulerian-Lagrangian simulation of transient spray from a multi-hole GDI Injector: Influence of injection and ambient pressures

 

Abstract:

The present work focuses on 3D numerical analysis of dispersion of iso-octane spray droplets injected from a high-pressure multi-hole injector into normal and high pressure ambience relevant, respectively, to full-load and part-load operation of GDI engines. The simulations are performed using Ansys Fluent 15.0 for two differ-ent injection pressures and ambient pressures. The operating conditions are same as in the experiments by Mi-troglou et al. (2006) Int. Jour. Engine Res. The gas phase is modelled by the Eulerian RNG k-ϵ model in con-junction with the Lagrangian Discrete Phase Model (DPM) for tracking the spray droplets. The mass, momen-tum and energy coupling between the droplet and the gas phases are accounted by appropriately modelling the source terms in the gas phase equations. The initial droplet size distribution is according to the Rosin-Rammler distribution function. The secondary atomization is modelled according to the Wave Model, with the collision outcomes amongst the droplets modelled as per the O’Rourke collision algorithm. The paper reports comparison of the spray characteristics with the experiments including time evolution of the spray morphology, penetration length and local average droplet size. The influence of higher injection pressure and ambient pressure on spray dispersion, evolution of droplet size and vapour concentration distribution within the spray are discussed. The effect of grid size on the numerical prediction of spray characteristics are highlighted for fuel injected in high pressure ambience.