Authors

P. Christoforetti, P. Kappacher, S. Plöckinger, E. Schutting, C. Trapp, H. Eichlseder, Institute of Thermodynamics and Sustainable Propulsion Systems, Graz University of Technology

Year

2026

Print Info

Production/Publication ÖVK

Summary

This paper links CFD-based mixture formation analysis with experimental combustion anomaly assessment on a 9 L Liebherr H964, PFI, spark ignited H₂ engine under steady-state and transient conditions. CFD resolves local air-fuel mixture (λ) fields and derives two mixture-quality indicators: the mass-weighted Uniformity Index (UI) and the Rich Mixture Share (RMS). A stationary combustion anomaly assessment procedure is then used to validate the simulation results by counting and categorizing combustion anomalies into Pre Ignition (PI), Knock (Kn), and Knocking Pre-Ignitions (PI-Kn) via fast measurement based criteria. Transient validation analyses the occurring combustion anomalies in standardized test cycles (NRTC and WHTC) and categorizes them like the stationary procedure. Results show that longer duration of injection (DOI) improves homogeneity, reduces rich pockets and lowers anomaly occurrence; injector cap design strongly affects outcomes. The RMS correlates robustly with anomaly trends across various configurations, outperforming the UI, which proved inconsistent in some cases. In transient cycles, a low-rail-pressure calibration (longer DOI) generally reduces both total anomalies and pmax critical events compared to a high-rail-pressure calibration with shorter DOI, at comparable transient response. These results confirm the correlation between CFD simulations and the two different experimental test procedures for evaluating the combustion anomaly tendency of various concepts. Furthermore, they demonstrate the critical importance of good mixture formation in hydrogen internal combustion engines.

ISBN

978-3-9504969-5-6

DOI

https://doi.org/10.62626/3epk-mpa5 Copy link

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