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The present work is dedicated to the study of air-natural gas mixing in a model intake manifold for Natural Gas Spark ignition engine. A configuration of continuous Natural Gas injection is considered. The fuel injection located upstream the intake valve is submitted to a time varying crossflow with high acceleration and deceleration levels. A physical analysis is developed and presented. Relevant new non-dimensional numbers are established for the engine situation. With this analysis, we compute a critical diameter of injection that characterizes the sensitivity of the jet to the pulsed transverse flow. Experiment is used to check these predictions. Schlieren technique is applied in a test section to obtain instantaneous images of the injection jet phased in the engine cycle. We visualize the global behavior of the jet and consequently the mixing in the intake manifold.

Hydrogen-fueled internal combustion engines (H2ICEs) have emerged as a promising technology for reducing greenhouse gas emissions in the transportation sector. However, due to the unique properties of hydrogen, especially under ultra-lean conditions, the combustion characteristics of hydrogen flames differ significantly from those of conventional fuels. This research focuses on evaluating the combustion process and cycle-to-cycle variations (CCVs) in a single-cylinder port-fuel injection H2ICE, as well as their impact on performance parameters. To assess in-cylinder combustion, three indicators of flame development are utilized and compared to the fundamental properties of hydrogen. The study investigates the effects of various factors including fuel-air equivalence ratio (ranging from 0.2 to 0.55), engine load (IMEP between 1 and 4 bar), and engine speed (900 to 1500 rpm).