Experimental investigation of injection strategies and in-cylinder turbulence effects on the performance of hydrogen fuelled light duty engines

Hydrogen is emerging as a key fuel in current research due to the urgent need to reduce environmental pollution caused by transportation and to enhance energy independence within European Union countries. Non-carbon energy sources such as nuclear power and renewable energy are being used to produce hydrogen, leading to the so called pink and green hydrogen. Fuelling internal combustion engines with hydrogen is considered a viable industrial solution, as existing gasoline or diesel engines can be retrofitted to operate with this fuel. However, hydrogen is prone to abnormal combustion phenomena and can potentially lead to high NOx formation due to its elevated combustion temperature. Therefore, careful research and development of future hydrogen engines is required to ensure reliability and efficiency. In particular, this thesis aims to perform a comparative analysis of different hydrogen injection strategies, namely direct injection (DI), port fuel injection (PFI), and premixed operation in hydrogen internal combustion engines. The study focuses on identifying the main differences, advantages, and limitations of each strategy in terms of combustion behaviour, engine performance, and emissions. The ultimate objective is to provide a clear physical interpretation of the observed trade offs, supporting future engine development and contributing to the advancement of sustainable transportation.