Large-eddy simulations of a spark ignition ic engine

Cycle-To-cycle variations of flow and combustion in internal combustion engines limit their fuel efficiency and emissions potential. Large-eddy simulation is an effective method to simulate fired engine operation, including accounting for cycle-To-cycle variations. In this research, large-eddy simulations of in-cylinder processes in a single-cylinder optically accessible spark-ignition piston engine are performed. The engine grid is created using ES-ICE, and is refined in the spark-plug vicinity, to better capture early flame development. STAR-CD is utilized to carry out the simulations, using a modified thickened flame model for turbulent premixed flame propagation and a Smagorinsky model for sub-grid-scale turbulence. Multiple engine cycles are simulated successively for steady-state motored and firing engine operation. Here the fired results are for homogeneous stoichiometric premixed reactants. The eventual goal is to develop a predictive tool for CFD simulations of direct-injection stratified-charge spark-ignition engines, which can be used to investigate cycle-To-cycle variations in flow and combustion.