CFD Analysis of the Combustion of Bio-Derived Fuels in the CFM56-3 Combustor

• Autor(a) principal: Oliveira, Jonas Miguel Pires
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/6527
• topic: Ansys Fluent; Biocombustíveis; Câmara de Combustão; Catia V5; Cfd; Cfm56-3; Emissões; Helyx-Os; Tap; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

A CFD simulation of a CFM56-3 combustor burning Jet-A and a 100% blend of biofuels, is performed. It is intended to evaluate the viability of these biofuels in a combustion point of view, by analysing the emissions and the energy extracted when burning these through ICAO's LTO cycle, so that these biofuels can be considered as a future civil aviation fuel. The three biofuels considered for this study were extracted from jatropha seeds, algae and sunflower. Due to the confidentiality that exits among GTE manufacturers, it is very difficult to obtain the blueprint of any given part of a GTE, and the combustor in study was no exception. Fortunately TAP kindly provided an operational CFM56-3 combustor, and with the aid of a 3D scanner, named Spider from Artec group, which belongs to UBI, it was possible to create a 3D model of the combustor. From this 3D model, an STL file can be exported, and then imported into CATIA V5, which is the software chosen to perform the CAD. All of the relevant parts of the combustor is represented, which include the primary and secondary swirlers, fuel injectors, cooling holes, walls and the dome; only one quarter of the combustor was used for the numerical study due to the existing symmetry, and due to the fact that within the existing 20 fuel injectors, there are four of them that inject the fuel with a richer mixture. The numerical mesh is created using HELYX-OS and the commercial software ANSYS Fluent 15.0 is used to perform the numerical study. Due to the complexity of this study, the atomization of the fuel was not considered. The viscous model used is the RSM; all of the air-inlets as well as the fuel injectors are defined as mass-flow inlets, and the exit of the combustor is defined as a pressure-outlet. The final results show reasonable agreement with the reference values presented by ICAO, when Jet-A is combusted, representing an error in general very low. Among all of the fuels simulated, it was proved that increasing the power produced higher NOx and lower UHC; however an unexpected behaviour of CO emission decrease with a power increase, was predicted. The biofuel that presented the best performance in ICAO's LTO cycle regarding NOx, CO and UHC emissions was sunflower biofuel, as these emissions were lower when compared to all of the fuels. Jatropha biofuel presented the highest CO2 reduction, representing a 20% decrease from Jet-A, and the energy extracted represented a minimal decrease of 6% when compared to the same fuel. Overall, it can be concluded that the biofuels studied have the potential to replace kerosene, and despite more biofuel has to be burned to produce the same amount of energy as Jet-A, a significant reduction in emissions is predicted.