Investigation of vibration on an airfoil aerodynamics at larger incidence

It is well known that the model wing may appear obvious vibration in wind tunnel experiments sometimes at high incidence especially in large aspect ratio aircraft models. The vibration modes mainly come in plunging and pitching which seriously affect the precision and reliability of wind tunnel experiments results. In this paper, the investigation of NACA0008 airfoil is carried out. Based on the unsteady Reynolds-Averaged Navier-Stokes equations, applying the modified infinite interpolation approach and the C type grid, the flow field and aerodynamic characteristics of the airfoil at high incidence are studied for simulating vibrations of wind-tunnel models, especially for the wind-tunnel airplane with high aspect ratio wing. Two vibration models and the phase delay between the different vibrations are also studied. It is shown that the vibrations of the airfoil can cause large scale unsteady separate vortex shedding before the stall incidence, and lead to the stall appearing at some lower incidence than the steady meaning stall incidence.The different phase delay has different effect on the flow-field.