Multi-equilibrium states phenomenon of separated flow for cambered airfoils at high incidences

Coupled with k-ω SST turbulent model, the unsteady Reynolds-averaged Navier-Stokes equations are solved in the time-domain to obtain the steady and/or unsteady separated flows for cambered airfoils at high incidences. Certain kinds of vibrations are designed for the airfoils. The effects of the airfoil camber on multi-equilibrium states phenomenon for the separated flow are studied. It is found that multi-equilibrium states exist for the separated flows around the airfoils with camber of 2%. Compared with symmetrical airfoil of the same thickness which is larger than 20%, the range of incidences increase about 2° and start incidence decrease around 1°. The equilibrium state transition phenomenon occurs around the NACA 2416 airfoil with relatively small thickness. It is obvious that the camber of airfoil conduces to the equilibrium state transition phenomenon of separated flow to some degree.