Development of a Large-Eddy Simulation Methodology for the Analysis of Cycle-to-Cycle Combustion Variability of a Lean Burn Engine

Ultra-lean burn conditions (? > 1.8) is seen as a way for improving efficiency and reducing emissions of spark-ignition engines. It raises fundamental issues in terms combustion physics its modeling, among which the significant reduction laminar flame speeds increase thickness, well an increased sensitivity to local fuel/air equivalence ratio variations are essential be accounted compared conventional stoichiometric mixture conditions. In particular, effects modified characteristics on stretch during early development spark ignited gasoline engine can expected become importance. present work, Large-Eddy Simulation approach presented applied study cycle-to-cycle direct injection operating both ultra-lean The Coherent Flame Model used enriched via correlation velocity accounting nonlinear effects. stretched calculations validated against experimental results. Then, different points computed assessing capacity reproduce regimes. results analyzed variabilities influence spark-plug orientation studied. Finally, detailed analysis with particular emphasis initial kernel lean extreme cycles burn. A strong by one third was observed lean-burn due non-linear occurring stage while almost no change Moreover, proposed capable handling various featuring significantly regimes (one order magnitude Karlovitz number) only minor model parameterization.