Unsteady aerodynamic behavior of an airfoil with and without a slat

Abstract

Unsteady flow behavior and load characteristics of a 2-D VR-7 airfoil with and without a leading-edge slat were studied in the water tunnel of the Aeroflighdynamics Directorate, NASA Ames Research Center. Both airfoils were oscillated sinusoidally between 5° and 25° at Re = 200,000 to obtain the unsteady lift, drag and pitching moment data. A flourescent dye was released from an orifice located at the leading edge of the airfoil for the purpose of visualizing the boundary layer and wake flow. The flow field and load predictions of an incompressible Navier-Stokes code based on a velocity-vorticity formulation were compared with the test data. The test and predictions both confirm that the slatted VR-7 airfoil delays both static and dynamic stall as compared to the VR-7 airfoil alone.