Dissertation in Mechanical Engineering Mahmoud Gadalla (M.Sc. Tech.)
Opponent Professor Christian Hasse, Technical University of Darmstadt, Darmstadt, Germany
Custos Professor Ville Vuorinen, Aalto University, School of Engineering, Department of Mechanical Engineering
Via Zoom; https://aalto.zoom.us/j/62016365922
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Climate change is a real problem that the world is currently facing. Various efforts have been dedicated to curb the fossil-derived carbon dioxide (CO2) emissions, especially in the energy sector. In the research community of internal combustion engines (ICE), a major aim is to seek carbon-neutral pathways that mitigate climate change effects for ICE in heavy industry and marine shipping applications.
The present dissertation belongs to the research fields of computational combustion physics and fluid dynamics. The primary focus therein is to model and simulate diesel spray assisted combustion of alternative fuels, namely methane, methanol, and hydrogen. Presently, the physicochemical characteristics of spray assisted combustion processes are not well understood for alternative fuels. Such aspects are further explored in this dissertation. In addition, the numerical modeling efforts are technically challenging as well, since they require modeling complex fluid flows involving turbulence, phase change, and chemical reactions under engine-relevant conditions.
The dissertation comprises four research articles, investigating the combustion characteristics of various alternative fuels when ignited by pilot diesel spray. While Publication I revisited the numerical framework and modeling assumptions for evaporating sprays, Publication II investigated the ignition characteristics of methanol as an alternative fuel, compared with methane, when ignited by a pilot diesel spray. The challenges identified therein for methanol ignition were further addressed in Publication III. There, hydrogen enrichment to the premixed charge was proposed as a chemical remedy to facilitate methanol ignition, while extending the operational window. Finally, in Publication IV the focus was shifted to beyond the spray autoignition, wherein local numerical microscopy was conducted to investigate the combustion mode development in a high fidelity scale-resolved simulation. In summary, the present dissertation pioneers high-fidelity numerical investigations on alternative fuel spray-assisted combustion problems.
Contact information mahmoud.gadalla@aalto.fi tel +358504720381