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Caracterização do túnel aerodinâmico da Academia da Força Aérea
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Abstract(s)
O túnel aerodinâmico da Academia da Força Aérea é uma infra-estrutura única a nível nacional, que permite a simulação de escoamentos em torno de modelos para validação de análise aerodinâmica e de estabilidade. De forma a tirar partido do seu potencial, é necessário garantir uma qualidade mínima do escoamento na zona de trabalho, nomeadamente um campo de pressão constante e escoamento perpendicular à secção de trabalho. Adicionalmente, revela-se fundamental saber as condições dos sensores de medição de forças e momentos aplicados nos modelos.
Com o objectivo de dotar a Academia da Força Aérea com uma ferramenta que permita efectuar uma caracterização do escoamento, foi actualizado o sistema de atravessamento. Deste modo, torna-se possível recolher valores de pressão num volume da secção de teste do túnel aerodinâmico, com o formato de grelha rectangular com parâmetros definidos pelo utilizador.
Com recurso à ferramenta desenvolvida na presente dissertação, foi efectuada uma caracterização do escoamento do túnel aerodinâmico. Deste modo, definiu-se um volume de uniformidade de pressão com dimensões 0,6×1,1×1,4 m. Dentro do volume, obteve-se uma variação de pressão dinâmica de 2,7%, um ângulo α médio de -0,92º e um β de -0,52º.
Foi possível verificar que a balança de medição de forças e momentos do túnel aerodinâmico apresenta resultados reais. No entanto, o plano de simetria, quando exposto ao escoamento, poderá criar uma força no adaptador para um meio modelo de 10N, o que interfere com os resultados obtidos em análises anteriores.
Desta forma, a Força Aérea obtém a capacidade de ser efectuada uma caracterização do escoamento do túnel aerodinâmico de forma célere. Conclui se também que todos os parâmetros que estão fora dos limites do projecto de implementação, já o estavam na última caracterização efectuada.
The Portuguese Air Force Academy wind tunnel is a unique facility at national level, allowing flow simulation around models for validation of aerodynamics analysis and stability. In order to take advantage of its potential, it is necessary to ensure a minimum quality of flow in the working area, namely a constant pressure field and flow perpendicular to the section test. Additionally, it is important to have calibrated sensors to measure forces and momentums. With the objective of providing the Portuguese Air Force Academy with an apparatus which allow a flow characterization, the traverse system was updated. Thus, it becomes possible to collect pressure data in a volume within the working area of the wind tunnel, in the form of a rectangular mesh with user defined parameters. With the apparatus developed on the present dissertation, a wind tunnel flow characterization was made. Results had shown that it is possible to define a uniformity pressure volume with dimensions 0,6×1,1×1,4 m. Within the volume, a 2,7% dynamic pressure variation was found, alongside with an average α of -0,92º and a β of 0,52º. It was possible to ascertain that the wind tunnel momentum and strain measuring balance renders reliable values. Nonetheless, the symmetry plane, when exposed to flow, may produce a force of 10N on the half-model adapter, which interferes with the results obtained in previous analyzes. In this work was developed a method to perform a prompt wind tunnel flow characterization. It is also concluded that all parameters out of the limits of wind tunnel implementation project, were already in the last performed characterization.
The Portuguese Air Force Academy wind tunnel is a unique facility at national level, allowing flow simulation around models for validation of aerodynamics analysis and stability. In order to take advantage of its potential, it is necessary to ensure a minimum quality of flow in the working area, namely a constant pressure field and flow perpendicular to the section test. Additionally, it is important to have calibrated sensors to measure forces and momentums. With the objective of providing the Portuguese Air Force Academy with an apparatus which allow a flow characterization, the traverse system was updated. Thus, it becomes possible to collect pressure data in a volume within the working area of the wind tunnel, in the form of a rectangular mesh with user defined parameters. With the apparatus developed on the present dissertation, a wind tunnel flow characterization was made. Results had shown that it is possible to define a uniformity pressure volume with dimensions 0,6×1,1×1,4 m. Within the volume, a 2,7% dynamic pressure variation was found, alongside with an average α of -0,92º and a β of 0,52º. It was possible to ascertain that the wind tunnel momentum and strain measuring balance renders reliable values. Nonetheless, the symmetry plane, when exposed to flow, may produce a force of 10N on the half-model adapter, which interferes with the results obtained in previous analyzes. In this work was developed a method to perform a prompt wind tunnel flow characterization. It is also concluded that all parameters out of the limits of wind tunnel implementation project, were already in the last performed characterization.
Description
Keywords
Caracterização do escoamento Sistema de atravessamento Sonda de sete-furos Balança de seis componentes Flow characterization Traverse system Seven-hole pressure probe Six-component balance
Citation
Publisher
Academia da Força Aérea