LES investigation of cycle-to-cycle variation in a SI optical access engine using TFM-AMR combustion model

Multi-cycle large-eddy simulations (LES) are performed to investigate combustion cycle-to-cycle variability (CCV) in a gasoline spark ignited optical access engine operating under homogeneous stoichiometric conditions. Combustion is addressed with the Thickened Flame Model (TFM) and finite rate chemistry accounted for through reduced oxidation reaction mechanism. In view of fact that computational costs LES still very high today, this work investigates use adaptive mesh refinement (AMR) flame zone conjunction artificial thickening applied by TFM model. The paper discusses how resulting coupled TFM-AMR model allows good resolution flame, maintaining accuracy at acceptable costs. First, details presented effects parameters explored, highlighting their impact on prediction. Then, fluid dynamics (CFD) simulation results validated against experimental data collected low-speed low-load point, comparing 20 cycles 100 measured cycles, mass fraction burned, phasing, images CCV indices. Lastly, detailed investigation fastest slowest numerical presented, analyzing instantaneous structures, ignition behaviors, propagation speeds, probability density function (PDF) velocity fluctuation around region. show highly correlated resolved field turbulence intensity, which found be main cause affects early kernel growth. This an attempt internal engines.