Integrated CFD-Experimental Methodology for Hydrogen-Fuelled Small Loop Scavenged Two-Stroke Engines

This paper presents an integrated methodology for the analysis of hydrogen-fuelled two-stroke engines, combining experimental data, 1D CFD simulations, and 3D CFD combustion calculations. The proposed approach aims to enhance the understanding of scavenging, injection, and combustion processes in a 50 cc loop-scavenged engine with low-pressure direct hydrogen injection (LPDI), experimentally studied on a test bench. The performance of the hydrogen-fuelled engine was slightly lower compared to gasoline operation, achieving a maximum power output of 3.1 kW compared to 3.6 kW with gasoline, using a slightly lean air-fuel ratio (lambda = 1.3). The maximum engine speed for stable combustion without knocking was achieved at wide-open throttle (WOT) at 7000 RPM. The developed 1D CFD model, based on the layout at the test bench, was calibrated using average experimental data and specific full-load operating points. 3D CFD simulations were performed for two full-load operating points, focusing on combustion dynamics and fuel distribution within the chamber, with combustion model parameters calibrated to ensure consistency with experimental data. The integrated approach resulted in a good agreement between numerical results and experimental data. The proposed methodology enables accurate model calibration and a deeper understanding of complex physical phenomena, representing a valuable tool for the development of low-emission engines.