CFD Analysis of the Flow Over a National Advisory Committee for Aeronautics (NACA) 0009 Airfoil

Abstract

The study of flow over an airfoil is crucial in the design of parts in flight applications. The correct shape of airfoils has a large impact on the performance of an aircraft. There are different flow regimes depending on the free stream conditions. The analysis of the two dimensional subsonic flow over a National Advisory Committee for Aeronautics (NACA) 0009 airfoil at various air velocities and operating at different angles of attack is presented. The flow was obtained by solving the steady-state governing equations of continuity and momentum conservation combined with the turbulence model [K-ε Realizable] in Fluent 6.3.26 aiming to the validation of these models through the comparison of the predictions and the free field experimental measurements for the selected airfoil. The aim of the work was to show the behavior of the airfoil under these working conditions. The above conditions can be visualized as a section of helicopter rotor along its wing span where the chosen operating conditions validate. The computational domain was composed in a structured way, taking care of the refinement of the grid near the airfoil in order to enclose the boundary layer approach. Calculations were done for variable air velocity altering the air velocities for every turbulence model tested. The k-ε model is one of the most common turbulence models, although it just doesn't perform well in cases of large adverse pressure gradients. It is a two equation model, that means, it includes two extra transport equations to represent the turbulent properties of the flow. These two extra turbulent properties are, the turbulent kinetic energy K and the turbulent dissipation rate ε. The turbulence models used in commercial CFD codes don’t give accurate results for high angle of attacks.
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