Experiment investigation and principium analysis for vibration on aerodynamics of an model airfoil at larger incidence

Using the equipments in NF-3 wind tunnel which are specially designed to do plunging and pitching movement, NACA0012 airfoil is chosen to test with larger incidences. Its aerodynamic characteristics is investigated and analysed. And based on the solution of unsteady Reynolds-Averaged Navier-Stokes equations, the flow field around airfoil at high incidences are investigated under consideration of vibrations for wind-tunnel models. It is shown that the vibrations of the airfoil can cause large scale unsteady separated vortex shedding before the stall incidence, therefore, lead to lift decreasing and the stall appearing at some lower incidence than the steady meaning stall incidence. Concerning these two vibration modes, the effects of airfoil's pitching is serious than that of plunging. So the chord stiffness should be stronger in the process of model's design.