Akademik Veri Yönetim Sistemi
INTERNATIONAL JOURNAL OF MICRO AIR VEHICLES, cilt.7, sa.3, ss.301-326, 2015 (SCI-Expanded)
Even for the stationary airfoils, due to the boundary and shear layer interactions of upper and lower surface of the airfoils, alternating vortex patterns form and the flow becomes time dependent. In the current study, the unsteady behavior of the flow around a symmetric airfoil is considered as incidence angle increases. The flow patterns are presented for wide range of angles of attack values. The vortex pattern generated is analyzed numerically for different angles of attack at Re=1000 around NACA 0012 airfoil. At this Reynolds number, the flow is laminar and boundary layers are quite thick. Flow separation and unsteady vortex shedding is observed even at low angles of attack. For NACA 0012 airfoil, the unsteady vortex pattern is observed at about 8 degrees angle of attack for Re=1000. Spectral analysis is performed for angles of attack ranging from 0 degrees to 90 degrees. It is presented that amplitude spectrum of lift coefficient (C-l) start to shows a peak at 8 degrees for NACA 0012 and the aerodynamic forces presents oscillatory behavior afterwards. The effect of angle of attack to wake pattern and instantaneous and mean aerodynamic coefficients are discussed. The time-averaged streamlines, pressure and skin friction coefficients are analyzed to observe the vortex formation and separation from the airfoil upper surface at this low Reynolds number.