High-lift performance enhancement using active flow control

The aerodynamic performance of conventional high-lift systems is typically achieved using multi-element flap configurations with cross-stream gaps that necessitate the use of complex positioning mechanisms with significant penalties in terms of weight, part count, and fabrication cost. In the present investigation, the performance of a high-lift airfoil in Fowler flap and simple flap configurations is enhanced using active aerodynamic flow control. Actuation is applied using a spanwise arrays of fluidically oscillating jets located upstream and downstream of the leading edge of the flap that increase the extent of flow attachment along the surface of the flap at deflections of up to 60°. Actuation leads to significant improvement in the performance of the Fowler flap compared with an optimized baseline configuration (C_L increased by up to 30%) and enables the high-lift performance of a single-element, simple flap without a cross-stream gap to match or exceed the performance of the optimized baseline Fowler configuration. It is also shown that incorporating a cross-stream gap with the simple flap enables increased lift at reduced actuation levels.