Experimental study of the effect of the reduced frequency in the airfoil's aerodynamic characteristics

The aim of this research is to describe a dynamic system developed to analyse the characteristics of airfoils immersed in an unsteady flow, being able to reproduce different movement including coupled bending and torsion. Using an airfoil model with pressure taps, NACA 0015 was analysed in two cases: bending motion and flutter, both with a reduced frequency of 0.086. The hysteresis loops of both cases are presented. An outstanding different of c1 and cd was observed depending on whether the effective angle of attack was increased or decreased. The need to create a catalogue of airfoils in unsteady regime is revealed.