LARGE EDDY SIMULATION OF GASOLINE SPRAYS IN A LAGRANGIAN-EULERIAN FRAMEWORK USING THE HIGH-ORDER SPECTRAL ELEMENT METHOD

Predicting the spray evolution using simulations requires accurate modeling of the turbulent gas-phase flow field. In this study, the high-order spectral-element method (SEM), implemented in the code Nek5000, was used to provide highly-resolved solutions to the turbulent flow field. Spray modeling capabilities were implemented into the Nek5000 code. The spray is modeled in a Lagrangian-Eulerian (LE) framework, where the liquid is represented by discrete parcels of droplets. The method for coupling liquid and gas in the context of SEM is described, which allows for very fine meshes to be used without affecting the stability of the solution. Large-eddy simulations (LES) of the eight-hole ECN Spray G gasoline injector were conducted. Numerical results are compared against experimental data for liquid penetration, droplet size and gas velocity. The morphology of the multi-plume spray is compared against experimental data. The effect of different spray injection inputs is analyzed. It was found that using a plume direction of 33 degrees and an injection cone angle of 30 degrees produced the best results overall. This work shows the applicability of SEM for spray modeling applications, where use of a high-order flow solver can help us understand the multi-plume spray aerodynamics and how it leads to plume collapse under certain conditions. Results also highlight the need for tuning spray input parameters in the LE framework, even when high-fidelity gas flow solutions are possible.