Background Trapezoidal sharp-edged wings common in today’s fighter aircraft. Little understanding of aerodynamic effects at sweeping angles between 30° and 40° AOA. Biconvex is reason for trying work on a circular arc airfoil.

Background (cont.) Two basic elements of this lab *sharp-edged wings * swept wings Low-sweep wings stall like *unswept wings or *delta wings Shear layer is a vorticity layer

Facilities and models Stability Wind Tunnel with U∞=40 m/s Re≈106 44” span trapezoidal wing Pressure taps Seven-Hole Probes New: 3-D Particle Image Velocimetry (PIV)

The oscillating mechanism and laser positioning feedback mechanism.  

Flow control with Oscillating mini-flap (AOA=10 degrees)

Sharp-edged wing with the leading –edge attachment that houses the rotating cylinder and the accumulator chamber.

Pressure Distributions along the span

Pressure profiles; Re=106 y/s=0.335

Trefftz Planes, =13° , Re=106 Axial velocity Vorticity

Trefftz Planes at Stability, =21°, Re=106 Axial velocity Vorticity

Pressure ports location

Time-Resolved DPIV Sneak Preview of Our DPIV System Data acquisition with enhanced time and space resolution ( > 1000 fps) Image Pre-Processing and Enhancement to Increase signal quality Velocity Evaluation Methodology with accuracy better than 0.05 pixels and space resolution in the order of 4 pixels

PIV results Streamlines and vorticity contours along a plane parallel to the stream half way outboard (left) and detail of field (right). Actuator increases back pressure, no secondary frequencies introduced so it does not suffer from nonlinear interactions

Vortex Patterns Visbal and Gursul call it “dual vortex structure”

Results (cont.) Plane A, t=2T/8,t=3T/8

Results (cont.) Plane A, control, t=4T/8,t=5T/8

Results (cont.) Plane A, control, t=6T/8,t=7T/8

Results (cont.) Plane D, no control and control

Flow animation for planes A-D