Date of Award
Spring 4-20-2026
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Mechanical Engineering
First Advisor
Adam Dempsey
Second Advisor
Casey Allen
Third Advisor
Somesh Roy
Abstract
Hydrogen as an alternative fuel shows great promise to help reduce greenhouse gas emissions from heavy duty engines. However, the challenge for hydrogen engines is that hydrogen has very different combustion properties compared to conventional hydrocarbon fuels. Hydrogen has very high flame speeds, very low ignition energy, and very wide flammability limit. These properties result in hydrogen engines being prone to abnormal combustion. Abnormal combustion makes hydrogen engines difficult to control or can cause catastrophic damage to the engine, so it is important to avoid conditions where abnormal combustion occurs. Hot spots along the combustion chamber walls are often the source of initiating preignition in hydrogen engines, which is a form of abnormal combustion. The location of these hot spots can be predicted by performing computational fluid dynamics (CFD) coupled with conjugate heat transfer (CHT) analysis of the engine combustion system. The coupled simulation approach produces a temperature map of the combustion chamber surfaces which can be used to inform engine component design to minimize hot spots, as well as aiding injector design and fuel jet targeting to reduce interaction with hot surfaces than cause premature ignition of hydrogen. In this work, CFD coupled with CHT analysis was performed on a single cylinder heavy-duty hydrogen engine with pre-chamber ignition to understand how hydrogen combustion effects the temperature of the combustion chamber surfaces. It was determined that this method can predict the steady-state temperature distribution of the head, piston surfaces, and pre-chamber. These results can also be utilized to predict the transient effects the engine cycle has on the surface temperature distribution; additionally, the resultant spatially varying, steady-state surface temperature can be used to predict abnormal combustion, such as preignition, and can help understand the thermal effects of combustion on engine components. In this work, the simulation workflow was exercised to highlight an operating condition with normal combustion behavior. Subsequently, the operating condition was changed by lowering the overall excess air ratio of the engine, leading to higher surface temperatures, and ultimately aggressive combustion with preignition.