Autoren

Christian TRAPP¹, Vishal JOSHI², Ahmad ALKEZBARI², Saraschandran KOTTAKALAM³, Gregor ROTTENKOLBER³, Markus NENZEL^3 
1ITnA / TU Graz, AT; ²Universtität der Bundeswehr München, DE; ³Hochschule Esslingen, DE

Zusammenfassung

This study explores the potential of ultra-lean hydrogen combustion in spark-ignited engines with passive prechamber ignition (PCI) systems. Although hydrogen has favorable properties for clean combustion, issues such as ignition stability and flame propagation under lean conditions offset these benefits. PCI systems, which use high-energy turbulent jets to ignite the main chamber, offer a promising solution to these issues. A validated CFD framework was developed using AVL FIRE M, incorporating enhancements to the CADIM ignition model. Improvements such as modified plasma channel velocity and two-way thermal coupling were validated through experimentation using optical diagnostics, including the novel Forward Projected Background Oriented Schlieren (FPBOS) method. A modular PCI prototype with interchangeable components was manufactured to enable flexible experimental evaluation. Engine testing was performed on a single-cylinder research engine under ultra-lean hydrogen conditions (λ = 2.5–4.0) at 4, 10, and 16 bar IMEP. Even the non-optimized prechamber demonstrated improved combustion stability, reduced ignition delay and shorter combustion duration, as well as slightly increased efficiency, compared to conventional spark ignition. These results confirm the effectiveness of passive prechambers for clean hydrogen combustion and emphasize the importance of advanced simulation and modular prototyping in developing future-ready ignition systems. Further optimization of the prechamber geometry is underway, which is expected to further enhance these benefits and support the development of hydrogen combustion engines.

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