Numerical Analysis of a Single Droplet Combustion: Jet-A1, N-Dodecane, N-Hexadecane

• Autor(a) principal: Dias, Francisco José Ramos
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/13022
• topic: Combustão de Gota Isolada; Combustíveis Alternativos; Euler-Lagrange; Jet Fuel; Simulação Numérica; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Aeronáutica

There has been an increase in concerns about the planet earth and its resources throughout the past decades. The dependency on fossil fuels created a critical dilemma since transportation is currently fueled by traditional, not sustainable power sources. The originated climate crisis on fossil fuels demands action from mankind, specifically concerning the research on alternative ways of fueling the current methods of transportation. The implementation of Biofuels in transportation encourages future scientists and engineers as a realistic option among other different paths constructed to develop sustainable fuels. The study of the injection, impinging, evaporation, and combustion allows the improvement of the burning characteristics assuming a specific fuel within a combustion chamber. These investigations of the combustion and evaporation procedures improve the burning droplet performance and thus reduce the emitted emissions under the same circumstances. This study intends to numerically simulate the single droplet evaporation and combustion of fuel droplets in a drop tube furnace (DTF) that has the capacity of varying the ambient temperature. The numerical approach simplifies the physical phenomena by employing an Eulerian-Lagrangian approach, considering a discrete and a continuous phase, which is further accomplished while running in a CFD software. The continuous phase is computed recurring to a turbulence modeling, while the dispersed phase is separately computed using the discrete phase model. The computation of the combustion phenomenon is deeply related to the evaporation of the discrete phase employing the non-premixed combustion provided by the operating software. There is a 2D planar simplification of the 3D axisymmetric experimental cylinder followed by the respective discretization of the mathematical equations and pressure-velocity coupling. This work numerically simulates the burning phenomenon of n-dodecane, jet fuel, and nhexadecane single droplets. The obtained results of the droplet size reduction relating to time display agreement with the d 2 law and respective experimentally obtained data. The acquired outcomes also allow the establishment of correlations between the combustion characteristics and the droplet physics properties, such as velocity, displaying a reduction of the droplet velocity alongside the shrink of the droplet diameter. This information is visible for different temperature environments and fuels, suggesting a physical association. Besides this interpretation, the imposed droplet initial velocity variations (1.0 m/s until 1.3 m/s) do not affect the combustion characteristics outcomes. This study demonstrates a precise relation between the ambient temperature of the drop tube furnace (DTF) and the improvement of the combustion process and burning properties. Additionally, the chemical composition of the fuels influences the combustion characteristics and their performances. Overall, the numerical performed simulation can be improved and thus approximate the implemented simulation to the occurring physical event, allowing the development of the additional knowledge in this thematic.