The influence of the angle of attack (AoA) and the chord based Reynolds number (Rec) on the lift and drag coefficients
has been analyzed experimentally in a low-aspect-ratio NACA0012 airfoil, AR 2. Results are shown for chord based
Reynolds numbers in the range 3.33×104 ≤Rec ≤1.33×105 and AoA between 0º and +35º, the stall angle being close to
12º. The aerodynamic characteristics show an increase and decrease of lift and drag force fluctuations for AoA greater than
the stall angle. The explanation of how these aerodynamic variations appear has been reported numerically and it is based
on two-dimensional effects which are mainly the unstable laminar separation bubble (LSB) and the subsequent downstream
propagation of leading edge vortex (LEV) as AoA increases. In addition, the dynamic response of the wing has been studied
using frequency analysis. We compute the power spectral density (PSD) from the temporal evolution of the net force exerted
over the wing, showing that the main response of the wing is the presence of two natural frequencies of the wing-base system.
The mean PSDsuddenly increases for Rec ≈1×105, particularly at AoA exceeding the critical point that corresponds to the
stall angle. Finally, and despite from the fact that our model is rigid, we find PSD peaks at very low and high frequencies
in agreement with other authors’ results which correspond to energetic modes in the wingtip vortex and the formation and
emission of coherent turbulent structures behind the airfoil, respectively.
