Unsteady aerodynamics of flap cove flow in a high-lift device configuration

The unsteady flow around the flap cove region of a three-element high lift aerofoil configuration has been experimentally investigated using Particle Image Velocimetry (PIV) and Laser Doppler Anenometry (LDA). Measurements were carried out in the University of Southampton 3.5m x 2.5m and 2.1m x 1.7m wind tunnels on the two-dimensional National High Lift Programme (NHLP) model in typical landing configuration. The flow inside the flap cove resembles that of a leading-edge slat A strong shear layer separates from the cove lip and rolls-up downstream into a series of large, coherent vortices. These impinge on the main element surface and are seen to strike the leading edge of the flap. The effect of the flap gap stabilising the flow is seen in Reynolds stress and turbulent kinetic energy profiles within the flap cove. The wake of the main element trailing edge resembles a mixing layer, with little evidence of vortex shedding