1. 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.

2. 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

3. 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)

4. The oscillating mechanism and laser positioning feedback mechanism.

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

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

7. Pressure Distributions along the span

8. Pressure profiles; Re=106
y/s=0.335

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

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

12. Pressure ports location

13. 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

14. 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

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

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

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

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

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

20. Flow animation for planes A-D