Experimental and Numerical Investigation of Hydrogen Injection and its Preliminary Impact on High Performance Engines Development

Under the proposed Green Deal program, the European Union will aim to achieve zero net greenhouse gas (GHG) emissions by 2050. The interim target is to reduce GHG by 55% by 2030. In the current debate concerning CO2-neutral powertrains, bio-fuels and e-fuels could play an immediate and practical role in reducing lifecycle engine emissions. Hydrogen however, is one of the few practical fuels that can result in near zero CO2 emissions at the tailpipe, which is the main focus of current legislation. Compared to gasoline, hydrogen presents a higher laminar flame speed, a wider range of flammability and higher auto-ignition temperatures, making it among the most attractive of fuels for future engines. As a challenge, hydrogen requires a very low ignition energy. This may imply an increased susceptibility to Low Speed Pre-Ignition (LSPI), surface ignition and back-fire phenomena. In order to exploit hydrogen's potential, the injection system plays an extremely important role. This paper focuses on the experimental characterization of an H2 Direct Injection (DI) injector in order to provide a wide and robust dataset to be used in three dimensional Computational Fluid Dynamics (3D CFD) simulation correlations. For reasons of safety and practicality, Schlieren measurements are performed mainly using helium whereas the transposition to hydrogen is conducted via comparison of helium vs. hydrogen measurements as well as 3D CFD simulations. Injection simulations will help to set targets for new combustion chamber architectures and assess mixture preparation formation to support next generation injector development for a high performance oriented H2 engine.