Development of an Experimentally Validated CFD Engineering Tool for Marine Engine Applications

Marine engine development is undergoing a challenging transition, dictated by the decarbonization frame set by the International Maritime Organization (IMO). In this context, new fuels, such as methanol and ammonia, are attractive choices. Developing reliable computational tools can support the understanding of engine aerothermochemistry and the overall engine development process. In the present study, a computational tool has been developed, using a KIVA-based Computational Fluid Dynamics (CFD) code as the main development platform, considering previous development by the authors. Here, special emphasis is placed on an appropriate adaptation of the cascade atomization and drop breakup (CAB) spray model, for marine diesel oil (MDO) sprays, using experimental results in a large spray combustion chamber (SCC) in the presence of swirling gas flow. The present computational results demonstrate a proper representation of flow structure and physics for nonreactive (evaporating and nonevaporating) and reactive spray flow, including important characteristics as penetration length at different ambient pressures, Sauter mean diameter (SMD), as well as ignition and flame development of reactive flow. Comparison with experimental data is good, especially for high ambient pressure, which is most relevant for marine engine operation. Finally, the validated CFD tool is applied in a large two-stroke marine diesel engine operating at full load, for different injection configurations, i.e., two to four injectors. Computational results suggest that use of two injectors, in lieu of three or four, may result in decreased exhaust NOx and soot emissions. The present work paves the way for CFD studies in large marine engines operating with new fuels.