Airfoil
Mostrando 25-36 de 52 artigos, teses e dissertações.
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25. Linear and nonlinear aeroelastic analyses of a typical airfoil section with control surface freeplay.
This work presents an extensive analysis on the linear and nonlinear behavior of three degrees of freedom typical airfoil section oscillating in a bidimensional incompressible flow. The nonlinearity is introduced by means of control surface freeplay. The theoretical modeling of the aeroelastic system is reviewed from structural and aerodynamic standpoint. Tw
Publicado em: 2010
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26. Aeroelasticidade transônica de aerofólio com arqueamento variável / Transonic aeroelasticity of variable camber airfoil
Os recentes desenvolvimentos na tecnologia de sistema aeronáutico de geometria variável têm sido motivados principalmente pela necessidade de melhorar o desempenho de aeronaves. O conceito de Morphing Aircraft, por meio da variação da linha de arqueamento, representa uma alternativa para sistemas aeronáuticos mais eficientes. No entanto, para aeronaves
Publicado em: 2010
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27. Unsteady aerodynamic coefficients obtained by a compressible vortex lattice method.
Unsteady solutions for the aerodynamic coefficients of a thin airfoil in compressible subsonic or supersonic flows are studied. The lift, the pitch moment, and pressure coefficients are obtained numerically for the following motions: the indicial response (unit step function) of the airfoil, i.e., a sudden change in the angle of attack; a thin airfoil penetr
Publicado em: 2009
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28. Heat and mass transfer in two-phase flow around airfoils with aeronautical anti-ice systems. / Transferência de calor e massa no escoamento bifásico em torno de aerofólios equipados com sistemas de antigelo aeronáuticos.
It is required to prevent ice accretion on wings and horizontal stabilizers because it may cause aerodynamic performance degradation, weight increase, flight control difficulties and, in critical cases, may lead to operational safety margins reduction. When aircraft flies through clouds containnig supercooled water droplets, which are in metastable equilibri
Publicado em: 2009
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29. Optimization study of airfoil performance using genetic algorithms / Otimização de desempenho de aerofólios supercríticos: uma abordagem baseada em algoritmos genéticos
The objective of present study is analyze the multi-objective optimization applied to transonic airfoils project comparing different ways to define the objective functions. The optimization is evaluated by the genetic algorithm NSGA-II. The results is analyzed using metrics of diversity and optimality for multi-objective problems, which two are proposed. The
Publicado em: 2009
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30. State-Space modeling and active aeroelastic control of a typical airfoil section with three degrees of freedom.
This dissertation presents a detailed analysis of a typical section model with three degrees of freedom. This is a classic model used for the study of basic aerodynamic and aeroelastic phenomena. The equations of motion are derived and discussed. The equations for the aerodynamic loads induced by arbitrary motion of the typical section and by arbitrary shape
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 10/09/2008
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31. Aerodynamic coefficient prediction using neural networks.
The present work discusses the application of neural networks for the accurate prediction of aerodynamic coefficients of airfoil and wing-body configurations. Meta-models based on neural-network are able to handle non-linear problems with a large amount of variables. In this highlight, an efficient methodology employing neural networks for predicting aerodyn
Publicado em: 2008
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32. A fast algorithm for inverse airfoil design using a transpiration model and an improved vortex panel method
A fast algorithm for inverse airfoil design using an efficient panel method for potential flow calculation is presented. The method employs linear vortex distributions on the panels and a consistent procedure for imposing the Kutta condition, thus eliminating the spurious aerodynamic loading that usually appears at a cusped trailing edge. The algorithm searc
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2007-12
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33. A numerical model for thin airfoils in unsteady compressible arbitrary motion
A numerical method based on the vortex methodology is presented in order to obtain unsteady solution of the aerodynamic coefficients of a thin airfoil in either compressible subsonic or supersonic flows. The numerical model is created through the profile discretization in uniform segments and the compressible flow vortex singularity is used. The results of t
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2007-09
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34. Numerical study of synthetic jet actuator effects in boundary layers
This work has as a fundamental objective the numerical study of the effects of synthetic jet actuators on the flow of the boundary layer developed on a flat plate and on a hypothetical airfoil. The aim is to obtain computational data to indicate how these effects may be used as a means of flow control, describing the dynamics of the synthetic jet in the pres
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2007-03
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35. Influência de uma rugosidade tridimensional isolada na transição de uma camada limite sem gradiente de pressão / Effect of an isolated 3-D roughness element on the transition of Blasius boundary layer
The current thesis is devoted to a study of the effect of a shallow 3-D roughness element on the evolution of a 2-D Tollmien-Schlichting wave in a Blasius boundary layer. The experiments were carried out under controlled disturbance conditions on an airfoil section which could provide a long run with zero pressure gradient flow. A pneumatically driven slit s
Publicado em: 2007
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36. Further developments in unsteady compressible vortex lattice method in two dimensional motion.
Unsteady phenomena like flutter, buffeting, rapid maneuvers in flight and gust entry are usually modeled and studied by a theoretical treatment involving potential flow methods. The resulting equation from this approach is the governing differential equation for general non-steady, non-viscous, potential flow known as convected wave equation. The disturbance
Publicado em: 2007