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Advisor(s)
Abstract(s)
O presente trabalho foca-se no projeto de uma câmara de combustão para um motor
turbohélice de reduzidas dimensões para ser aplicado num UAV capaz de operar com a
missão de vigilância, bem como na simulação do desempenho da respetiva câmara.
Dados os requisitos propostos, a configuração adequada para atender aos requisitos de
tamanho é a câmara de combustão anelar. No projeto de câmaras de combustão
destaca-se a análise de vários parâmetros, nomeadamente o diâmetro de referência, os
comprimentos das zonas primárias, secundária e de diluição, da distribuição de ar
nessas zonas, o dimensionamento do difusor, swirler e orifícios de admissão de ar.
Para a obtenção destes cálculos teve-se em consideração as condições iniciais de
projeto. Neste sentido, desenvolveu-se um modelo numérico para calcular as
dimensões geométricas da câmara de combustão com auxílio de um programa em
MATLAB. Após a geometria da câmara ficar definida, construiu-se um modelo
tridimensional da câmara de combustão utilizando o software SOLIDWORKS, de modo
a ser possível efetuar posterior análise do desempenho da câmara de combustão com
base na Dinâmica de Fluidos Computacional (CFD). A modelação via CFD possibilita a
análise do escoamento ao longo da câmara de combustão tendo em conta os efeitos da
viscosidade e turbulência, recorrendo-se a modelos de turbulência. O software utilizado
foi o ANSYS Fluent 2020 R2, para resolver numericamente o escoamento turbulento
optando-se por utilizar o método RANS, e como modelo de turbulência optou-se pelo
?? - ?? standard. O combustível utilizado foi o kerosene (??10??22), sendo que os
parâmetros analisados nas simulações numéricas foram o perfil de temperaturas ao
longo da câmara e à saída da câmara de combustão, a distribuição da fração mássica do
combustível, ????2, ?????? e ????. Os resultados obtidos demonstram concordância com a
literatura, nomeadamente a nível da distribuição de temperaturas ao longo da câmara
com destaque para a temperatura máxima na câmara se verificar na zona primária
atingindo cerca de 2086 ?? e registando-se um decréscimo da temperatura ao longo da
câmara, sendo a temperatura à saída da câmara de aproximadamente 1400 ??.
Relativamente às emissões produzidas pela câmara de combustão projetada, a
formação dos poluentes decorreu dentro das zonas estipuladas para existir uma
redução dos poluentes emitidos. Tal, denota a possibilidade de compreender o
comportamento do escoamento dentro da câmara de combustão, bem como a
viabilidade da câmara de combustão projetada ser aplicada em UAVs.
The present work focuses on a combustion chamber design for a small turboprop engine to be implemented in a UAV capable of operating with a surveillance mission, besides simulating the performance of the respective chamber. Considering the proposed requirements, an annular combustion chamber is the appropriate configuration to meet the size requirements. The combustion chamber design involves analysing various parameters, including the reference diameter, the lengths of the primary, secondary and dilution zones, the distribution of air in these zones, the sizing of the diffuser, swirler and air intake holes. The initial design conditions were considered when making these calculations. A numerical model was developed to calculate the geometric dimensions of the combustion chamber using MATLAB. After defining the geometry of the combustion chamber, a three-dimensional model of the combustion chamber was created using SOLIDWORKS, to subsequently analyse the performance of the combustion chamber using Computational Fluid Dynamics (CFD). CFD modelling enables analysing the flow through the combustion chamber, considering the effects of viscosity and turbulence, using turbulence models. The software used to solve the turbulent flow numerically was ANSYS Fluent 2020 R2, using the RANS method and the standard k-e turbulence model. The fuel used was kerosene (??10??22), and the parameters analysed in the numerical simulations were the temperature profile along the chamber, temperature at the exit of the combustion chamber, the distribution of the fuel mass fraction, ????2, ?????? and ????. The results obtained are in accordance with the published literature, in terms of the distribution of temperatures throughout the chamber, with the maximum temperature in the chamber being in the primary zone, reaching around 2086 K, and with a decrease in temperature throughout the chamber, with the temperature at the exit of the chamber being approximately 1400 K. Regarding the emissions produced by the designed combustion chamber, the formation of pollutants happened within the zones stipulated for there to be a reduction in the emissions of pollutants. This result shows that it is possible to understand the behaviour of the flow inside the combustion chamber, as well as the feasibility of the designed combustion chamber applying to UAVs.
The present work focuses on a combustion chamber design for a small turboprop engine to be implemented in a UAV capable of operating with a surveillance mission, besides simulating the performance of the respective chamber. Considering the proposed requirements, an annular combustion chamber is the appropriate configuration to meet the size requirements. The combustion chamber design involves analysing various parameters, including the reference diameter, the lengths of the primary, secondary and dilution zones, the distribution of air in these zones, the sizing of the diffuser, swirler and air intake holes. The initial design conditions were considered when making these calculations. A numerical model was developed to calculate the geometric dimensions of the combustion chamber using MATLAB. After defining the geometry of the combustion chamber, a three-dimensional model of the combustion chamber was created using SOLIDWORKS, to subsequently analyse the performance of the combustion chamber using Computational Fluid Dynamics (CFD). CFD modelling enables analysing the flow through the combustion chamber, considering the effects of viscosity and turbulence, using turbulence models. The software used to solve the turbulent flow numerically was ANSYS Fluent 2020 R2, using the RANS method and the standard k-e turbulence model. The fuel used was kerosene (??10??22), and the parameters analysed in the numerical simulations were the temperature profile along the chamber, temperature at the exit of the combustion chamber, the distribution of the fuel mass fraction, ????2, ?????? and ????. The results obtained are in accordance with the published literature, in terms of the distribution of temperatures throughout the chamber, with the maximum temperature in the chamber being in the primary zone, reaching around 2086 K, and with a decrease in temperature throughout the chamber, with the temperature at the exit of the chamber being approximately 1400 K. Regarding the emissions produced by the designed combustion chamber, the formation of pollutants happened within the zones stipulated for there to be a reduction in the emissions of pollutants. This result shows that it is possible to understand the behaviour of the flow inside the combustion chamber, as well as the feasibility of the designed combustion chamber applying to UAVs.
Description
Keywords
Ansys Fluent Câmara de Combustão Anelar Cfd Emissões Projeto Turbohélice