1D-CFD ANALYSIS ON A HYDROGEN-FUELLED HIGH-PERFORMANCE SPARK IGNITION ENGINE

The automotive sector is experiencing a challenging period due to the continuous tightening of the emission limits. The European Union is leading this transition with the “Green Deal”, which has set the goal of cutting Green House Gases (GHG) emissions by at least 55% by 2030 and the complete zeroing of new vehicles CO2 emissions starting from 2035. The usage of alternative fuels, such as hydrogen, in internal combustion engines can reduce emissions and be compliant with future stricter legislations. In such a framework, this thesis aims at assessing, through numerical simulations, the potential in terms of both performance and efficiency of a Hydrogen fuelled Internal Combustion Engine for hyper-car applications. Therefore, a 1D CFD model of a single-cylinder hydrogen engine has been developed in the commercial software GT-Suite. Particular attention is devoted to the development of a suitable methodology to properly estimate the combustion duration and the knock occurrence. The former, in particular, is calculated by assuming that the faster hydrogen combustion process is mainly related to the highest laminar flame speed and scaling a typical gasoline combustion Wiebe function accordingly. On the other side, the knock prediction relies on a phenomenological model developed by Gamma Technologies for hydrogen combustion. The analysis of the preliminary simulation results proved a good agreement with the data already available in the scientific literature. Afterwards, several sensitivity analyses were performed on the main engine operating parameters and configurations (e.g. turbocharged vs naturally aspirated engine) in order to assess their impact on the engine performance and efficiency. Among the sensitivities studied, as expected, lambda and intake valve timing are the ones affecting the most the engine performance. Moreover, the boost level as well is highly influential on the engine performance, with the turbocharged version being able to reach much higher levels of output power than the naturally aspirated engine. The single-cylinder engine achieves a specific brake power of 105 kW/l and 35% of indicated efficiency, running with a relative fuel ratio equal to 1,5 and a boost pressure of 3 bar. Finally, a 4-cylinders engine has been built based on the single-cylinder version, to have a confirmation of the methodology used in the study. More specifically, the multicylinder version has been modelled to conduct a deeper analysis of the turbocharger with a consequent optimization