1. THE EFFECT OF DOWNSTREAM SUCTION ON THE DELTA WING LEADING-EDGE VORTEX Zhou Ji, Jeff Marchetta, J. Hochstein and J. D. Mo University of Memphis, Memphis, TN 38152, USA K. X. He, and Alan Chow Alabama A & M University, Huntsville, AL 35862, USA

2. Introduction b Leading-edge vortex produces vortex lift on delta wing. b Vortex cores are susceptible to quick deterioration by external disturbances. b Vortex can be influenced by injecting a jet or lateral blowing, etc. b Vortex is controlled and lengthen by suction fan in this work.

3. Introduction

4. Introduction

5. Introduction

6. Experimental Set-up b Wind Tunnel: 2 2 foot low speed wind tunnel at the University of Memphis 20 inch low load driving fan is used instead of the original driving fan. Smoking wire technique is used to visualize the leading edge vortex.

7. Experimental Set-up b Half model of delta wing made of plastic. Leading-edge sweep angle: 60 O Chord length at the root: 11-1/2 inches Adjustable angle of attack: 15 o ~35 o

8. Experimental Set-up b Experimental parameters: Distance to the fan d Height to the fan h Angle of attack Angle of attack Power level of fan (6V or 18V) Reference length: chord length c

9. Experimental Results =25 o, no fan

10. Experimental Results =25 o, d/c=0, h/c=1/8

11. Experimental Results =30 o, no fan

12. Experimental Results =30 o, d/c=0, h/c=1/4

13. Experimental Results =30 o, d/c=0, h/c=1/4, high power

14. Experimental Results =30 o, d/c=0, h/c=1/8

15. Experimental Results =30 o, d/c=0, h/c=3/8

16. Experimental Results =30 o, d/c=0, h/c=0

17. Experimental Results =25 o, d/c=0, h/c=1/4

18. Experimental Results =25 o, d/c=0, h/c=0

19. Experimental Results =30 o, d/c=1/4, h/c=1/4

20. Experimental Results =30 o, d/c=1/2, h/c=1/4

21. Experimental Results =25 o, d/c=1/4, h/c=1/4

22. Experimental Results =25 o, d/c=1/2, h/c=1/4

23. Conclusions b The vortex is enhanced by properly positioned suction fan. b As the angle of attack increases, the influence becomes very apparent. b The optimal horizontal position is 0 height relative to trailing edge. b The optimal height is the at the vortex core. b Vortex enhancement increases with the fans speed.