A Combined Numerical and Experimental Investigation of Cycle-to-Cycle Variations in an Optically Accessible Spark-Ignition Engine

Abstract A combined numerical and experimental investigation is carried out to analyze the cycle-to-cycle variations (CCV) in an optically accessible spark-ignition engine with port fuel injection. stable unstable operating condition considered. Well-established turbulence, combustion, ignition models are employed large-eddy simulations (LES). High-speed measurements of velocity field via particle image velocimetry flame imaging tumble plane conducted experiments. detailed comparison between LES experiments out, including in-cylinder pressure, flow fields, spatial distribution, fields conditioned on fast slow cycles. Good agreement achieved for variables considering all cycles; yet, some discrepancies observed conditionally averaged quantities. systematic quantitative correlation analysis selected influencing CCV presented, which extracted from different length scales (r = 3 mm, 12 43 mm) distinguished early kernel development later propagation. Even though most relevant parameters two conditions, location coherent vortex structure found be important both cases.