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Abstract(s)
Desde muito tempo vários esforços tem sido feitos de maneira a optimizar o rotor dos helicópteros com o objectivo de reduzir a emissão de poluentes. Durante vários anos foram feitas várias optimizações estrutrais na pá do rotor.
Estudos recentes numéricos e experimentais mostram que para melhor a performance do rotor várias considerações aerodinâmicas têm que ser levadas em conta.
O principal objectivo deste trabalho é estudar e optimizar um mecanismo preliminar constituído por um flap dinâmico que consiga controlar a camada limite na pá. O flap escolhido foi o Gurney Flap, desenvolvido nos anos 70 por um piloto de automóveis com o intuito de provocar uma downforce de maneira a melhorar o desempenho do automovél. A razão desta escolha deve-se por
o flap ter uma superfície relativamente pequena com baixas forças de inércia permitindo baixos consumos de energia e sem adicionar extra carga para na pá. A utilização deste flap demonstrou
o aumento as propriedades aerodinâmicas de pá, portanto, reduzindo o consumo de combustÃvel.
Para este estudos várias análises estruturais foram realizadas usando softwares comerciais entre eles; análises cináticas, de maneira a estudar o deslocamento, velocidade e aceleraçao do mecanismo e também do sistema de actuação; análises dinâmica, possibilitando o calculo de tensões e deformações do sistema sujeito a várias cargas de inécia e por fim uma análise modal, bastante importante devido ao mecanismo estar sujeito a uma frequência de actuação.
Depois de conduzidas estas análises foi possivél optimizar o peso da desenho inicial em cerca de 50% respeitando todos os requerimentos impostos e as características do material. Foram estudados dois tipos de sistema de de actuação deixando em aberto a escolha do actuador.
Various efforts have been made in order to optimize the helicopter rotor with the objective to reduce the emission of pollutants. For several years many studies have conducted to a structural optimization of rotor blade. Recent experimental and numerical studies show that for the best performance of the rotor several aerodynamic considerations must be taken into account. The main objective of this work is to study and optimize a preliminary mechanism consisting in a dynamic flap that can control the boundary layer on the blade. The chosen flap was a Gurney flap which was developed in the 70’s by a race driver in order to cause a downforce improving the performance of the race cars. The reason for this choice is due to the flap having a relatively small surface with low inertial forces allowing low energy consumption and without adding extra load to the blade. The use of this flap has demonstrated to increase the aerodynamics properties of blade therefore reducing the fuel consumption. For this study a number of structural analyses were performed using commercial software between them: kinematics analysis in order to study the displacement, velocity and acceleration of the mechanism and also the actuation system; dynamic analysis , enabling the calculation of stress and strain of the system subjected to various inertial loads, and finally, a modal analysis, very important due to the mechanism being subject to a high frequency of actuation. After these analyses was possible to optimize the design of the mass in about 50% respecting all the requirements imposed and the characteristics of the material. There are two types of actuation system, while leaving open the choice of the actuator.
Various efforts have been made in order to optimize the helicopter rotor with the objective to reduce the emission of pollutants. For several years many studies have conducted to a structural optimization of rotor blade. Recent experimental and numerical studies show that for the best performance of the rotor several aerodynamic considerations must be taken into account. The main objective of this work is to study and optimize a preliminary mechanism consisting in a dynamic flap that can control the boundary layer on the blade. The chosen flap was a Gurney flap which was developed in the 70’s by a race driver in order to cause a downforce improving the performance of the race cars. The reason for this choice is due to the flap having a relatively small surface with low inertial forces allowing low energy consumption and without adding extra load to the blade. The use of this flap has demonstrated to increase the aerodynamics properties of blade therefore reducing the fuel consumption. For this study a number of structural analyses were performed using commercial software between them: kinematics analysis in order to study the displacement, velocity and acceleration of the mechanism and also the actuation system; dynamic analysis , enabling the calculation of stress and strain of the system subjected to various inertial loads, and finally, a modal analysis, very important due to the mechanism being subject to a high frequency of actuation. After these analyses was possible to optimize the design of the mass in about 50% respecting all the requirements imposed and the characteristics of the material. There are two types of actuation system, while leaving open the choice of the actuator.
Description
Keywords
Aerodinâmica Pás de rotor Aeronave Gurney flap
Citation
Publisher
Universidade da Beira Interior