A computational investigation of airfoil stall flutter

Abstract

A fully factorized two-dimensional Navier-Stokes flow solver has been developed and applied to the problem of predicting subsonic airfoil flutter in the light stall regime. The inviscid fluxes are evaluated with a central; difference ADI scheme and fourth and second order numerical dissipation is used to obtain oscillation-free solutions. The performance of algebraic and one-equation turbulence models in predicting separated flow is explored for computing high Reynolds number steady flow and unsteady flows over an oscillating NACA0012 airfoil. Comparisons of the computer results with available experimental data indicate that even though the lift reponse is fairly well predicted, the computation of the pitching moment hysteresis loops is very sensitive to turbulence modeling. Results compared with several current models are in good agreement whenever the steady stall angle is exceeded only slightly. However, they fail to capture the vortex shedding process leading to the onset of stall flutter.