Manipulation of Trailing Edge Separation on an Aerofoil Using a Periodic Cross-Flow

Experiments with an HQ-17 laminar aerofoil are described where flow separation in the recompression region of an aerofoil is reduced. A loudspeaker system is mounted inside the aerofoil. It generates an oscillating jet with a blowing and a suction phase in a spanwise slot in the aerofoil. Spanwise vortices are generated that enhance mixing processes, increasing the lift coefficient CL. The lift gain depends mainly on the position of the separation line relative to the slot as well as the frequency and the amplitude of the excitation.