A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of is key enabling control strategies, improving design reducing negative impact on operation. This paper presents a new simulation strategy which allows investigation individual physical quantities (e.g., flow field or turbulence quantities) separately. As first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations natural gas are performed. For each cycle, results just prior spark timing taken. Next, from different cycles combined: one quantity, e.g., field, extracted snapshot given all other taken cycle. Such combination yields snapshot. With combined snapshot, continued until end combustion. The obtained with snapshots show that velocity seems have highest CCV. Turbulence intensity, quantified by turbulent kinetic energy dissipation rate, has similar value for snapshots. their small compared field. novel methodology flexible sources been difficult investigate past.