Unsteady aerodynamic simulations of an oscillating airfoil with miniflaps

Abstract

Reynolds-Averaged Navier-Stokes computations of an oscillating airfoil equipped with a Gurney flap are conducted. The airfoil is oscillated at a reduced frequency of 0.13 between angles of attack of 0.0°14.4° at a chord Reynolds number of 169xl0. This range of angle of attack provides for light dynamic stall flow conditions. The results of the computations are compared with surface measurements from an experiment and show good qualitative agreement. The computational results show that during pitch-up of the airfoil there is little effect on the unsteady airfoil flow due to the Gurney flap; this is unlike the Gurney flap in a steady flow. However, during pitch-down the Gurney flap appears to delay the shedding of the vortices, increase the pressure difference at the airfoil's trailing edge and increase the overall lift coefficient. However there is a drag penalty associated with this increase in lift.