Early flame development characterization of ultra-lean hydrogen–air flames in an optical spark-ignition engine - Archive ouverte HAL
Article Dans Une Revue Proceedings of the Combustion Institute Année : 2024

Early flame development characterization of ultra-lean hydrogen–air flames in an optical spark-ignition engine

Résumé

Hydrogen-fueled internal combustion engines (H2ICEs) represent a promising technology for decarbonizing the transport sector. In pursuit of this goal, research is needed on lean hydrogen–air combustion under engine conditions aiming to mitigate NOx emissions. However, there is a limited amount of experimental data focusing on flame development at high pressure and temperature, especially in ultra-lean mixtures, which are recently considered to play an important role for future H2ICEs. This study investigates the behavior of very-lean to ultra-lean hydrogen–air flames (0.20 < φ < 0.55) in an optical spark-ignition engine, focusing on the early flame development phase. Fuel–air equivalence ratio and engine speed (900 < N < 1500 rpm) effects on hydrogen combustion are addressed with pressure-based heat release analysis and chemiluminescence flame imaging techniques. The findings revealed an intrinsic association between these two approaches. Hydrogen flames development measured before 2% of Mass Fraction Burned (MFB) strongly correlates with pressure-based quantities up to 50% MFB, underscoring the critical role of understanding the early flame phase for predicting total combustion duration and in-cylinder pressure traces. A model for hydrogen turbulent flames in the initial combustion stages is formulated based on the Zimont equation and the experimental data. An equation for 0D/1D combustion duration prediction up to 10% MFB is proposed, demonstrating its validity from the wrinkled flame to the well-stirred reactor premixed combustion regimes. Additionally, flame chemiluminescence images for each zone within the Peters–Borghi diagram are presented, offering valuable insights into the diverse characteristics of these flames.

Dates et versions

hal-04695263 , version 1 (12-09-2024)

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Caio Ramalho Leite, Pierre Brequigny, Jacques Borée, Fabrice Foucher. Early flame development characterization of ultra-lean hydrogen–air flames in an optical spark-ignition engine. Proceedings of the Combustion Institute, 2024, 40 (1-4), pp.105260. ⟨10.1016/j.proci.2024.105260⟩. ⟨hal-04695263⟩
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