Coupled LES Jet Primary Breakup - Lagrangian Spray Simulation of a GDi Multi-Hole Fuel Injector

Abstract

This paper presents results of a coupling of the Volume-of-Fluid Large-Eddy simulation (VOF-LES) of the jet primary breakup with a Lagrangian stochastic spray simulation of a GDi multi-hole injector. The objective is to assess the potential of replacing the phenomenological models of jet primary atomization with the stochastic parcel size-velocity data extracted from the VOF-LES analysis. The paper describes the methodology and assesses the predictive capability achieved, through comparison of the Lagrangian far-field spray simulation results with the complete experimental spray characterization data under the atmospheric ambient conditions. The injector sac-nozzle flow and jet primary breakup simulation is performed with the Open-FOAM code. The simulation of the spray development processes-of propagation, evaporation and secondary atomization-is performed with the AVL-FIRE commercial CFD code adopting the standard Lagrangian discrete droplet method. The comparison demonstrates good quantitative agreement for prediction of all significant far-field spray plume parameters, notably the trajectory, spread angle, tip penetration, footprint pattern and the droplet-size probability distribution function.

Modeling and Detailed Numerical Simulation of the Primary Breakup of a Gasoline Surrogate Jet under Non-Evaporative Operating Conditions

“…The ambient gas is then entrained into the gap between the liquid surface and the inner-hole wall. This phenomenon has also been observed in simulations for the full spray G injector [42].…”

“…1 distributed azimuthally [4]. The jets are spatially separated [6], therefore, ignoring inter-jet interaction will not influence the primary breakup in the near field [42,43].…”

“…Previous numerical studies on the full Spray G injector showed that when the liquid flows over the needle and enters the inner-hole, the liquid velocity at the inlet of the inner-hole is not aligned with the inner-hole axis [42]. The angle between the inlet velocity and the inner-hole axis is referred to as the "injection angle", denoted by α.…”

“…Low-fidelity simulations using Langrangian [39,29,40,30] and Eulerian [41] approaches have been performed to test the breakup models [29,40,41] and to investigate the inter-plume aerodynamics [39]. Recently, attempts have been made to perform LES of primary breakup including the whole injector geometry [42,43]. Yet due to the high Reynolds and Weber numbers involved, whether the mesh resolutions in these simulations were sufficient to faithfully resolve both the internal flow and the external turbulent sprays remains to be examined.…”

Time-dependent line-of-sight extinction tomography for multi-hole GDI injectors

“…The relevance of these velocity measurements are underscored in the study by Befrui et al. 27 The total surface area increases from approximately 0.5 (time of arrival of the drops at the measurement location) to 2.0 ms. This is consistent with an injection pulse width of 1.5 ms.…”