A methodology to initialize tumble flow fields for fast 3D-CFD simulations of pent-roof SI engines

Abstract The demand of powertrain technologies able to efficiently employ several non-fossil fuels types, as bio or synthetic ones, compels develop simplified strategies accelerate the engines industrial optimization. High-tumble ultra-lean SI are currently an attractive option, thanks their fuel flexibility and potential extending lean combustion limit with novel ignition strategies. This work presents a methodology initialize tumble flow fields at closed-valves inside pent-roof engines, without need simulating gas exchange process. First, assuming elliptical-shaped vortex, velocity field is initialized into cylinder according target ratio inlet valve closing (IVC). Then, evolved fixed piston position for time duration proportional integral scale turbulence. process essential adapt vortex morphology surrounding geometrical details, despite some kinetic energy lost due frictions. To compensate this last effect, re-scaled end match initial ratio. Finally, parameters affecting initialization calibrated by comparing development flow-field during compression stroke results from full-cycle simulation in engine. validated on Darmstadt optical numerical compared against PIV measurements different crank-angles. prediction also evaluated, assess quality field. achieved satisfactory, demonstrating applicability presented methodology.