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Flow Control over Sharp-Edged Wings

Flow Control over Sharp-Edged Wings. José M. Rullán, Jason Gibbs, Pavlos Vlachos, Demetri Telionis. Dept. of Engineering Science and Mechanics. Flow Control Team. P. Vlachos. J. Rullan. J. Gibbs. Overview. Background Facilities and models

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Flow Control over Sharp-Edged Wings

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  1. Flow Control over Sharp-Edged Wings José M. Rullán, Jason Gibbs, Pavlos Vlachos, Demetri Telionis Dept. of Engineering Science and Mechanics

  2. Flow Control Team P. Vlachos J. Rullan J. Gibbs

  3. Overview • Background • Facilities and models Experimental tools (PIV, pressure scanners, 7-hole probes) • Results: • Aerodynamics of swept wings • Flow Control at high alpha • CONTROL SEPARATED FLOW (NOT SEPARATION) • 10 4 < Re < 10 6 • Conclusions

  4. Background • Diamond-Planform, sharp-edged wings common on today’s fighter aircraft. • Little understanding of aerodynamic effects at sweeping angles between 30° and 40° AOA.

  5. Vorticity Rolling over Swept Leading Edges Sweep> 500 Sweep~450 Sweep~400 Sweep~400

  6. Background (cont.) • Low-sweep wings stall like *unswept wings or *delta wings Dual vortex structures observed over a wing swept by 50 degrees at Re=2.6X104 (From Gordnier and Visbal 2005)

  7. Yaniktepe and Rockwell • Sweep angle 38.7ºfor triangular planform • Flow appears to be dominated by delta wing vortices • Interrogation only at planes normal to flow • Low Re number~10000 • Control by small oscillations of entire wing

  8. Facilities and models • VA Tech Stability Wind Tunnel • U∞=40-60 m/s Re≈1,200,000 • 44” span diamond-planform wing

  9. Facilities and models • Water Tunnel with U∞=0.25 m/s Re≈30000 • CCD camera synchronized with Nd:YAG pulsing laser • Actuating at shedding frequency

  10. Wind Tunnel Model • Model is hollow. • Leading edge slot for pulsing jet • 8” span diamond wing • Flow control supplied at inboard half of wing

  11. Facilities and models(cont.)

  12. 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

  13. DPIV Digital Particle Image Velocimetry System III Conventional Stereo-DPIV system with: • 30 Hz repetition rate (< 30 Hz) 50 mJ/pulse dual-head laser • 2 1Kx1K pixel cameras Time-Resolved Digital Particle Image Velocimetry System I • An ACL 45 copper-vapor laser with 55W and 3-30KHz pulsing rate and output power from 5-10mJ/pulse • Two Phantom-IV digital cameras that deliver up to 30,000 fps with adjustable resolution while with the maximum resolution of 512x512 the sampling rate is 1000 frme/sec Time-Resolved Digital Particle Image Velocimetry System II : • A 50W 0-30kHz 2-25mJ/pulse Nd:Yag • Three IDT v. 4.0 cameras with 1280x1024 pixels resolution and 1-10kHz sampling rate kHz frame-straddling (double-pulsing) with as little as 1 msec between pulses Under Development: • Time Resolved Stereo DPIV with Dual-head laser 0-30kHz 50mJ/pulse • 2 1600x1200 time resolved cameras • …with build-in 4th generation intensifiers

  14. Actuation • Time instants of pulsed jet (a) (b) (c)

  15. PIV Results • Velocity vectors and vorticity contours along Plane D no control control

  16. PIV results (cont.) • Planes 2(z/b= 0.209) and 3 (z/b= 0.334) with actuation. Plane 2 Plane 3

  17. Results (cont.) • Plane A, control, t=0,t=T/8

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

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

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

  21. Results (cont.) • Plane 8, t=0 No control Control

  22. Results (cont.) • Plane 8, t=T/8 No control Control

  23. Results (cont.) • Plane 8, t=2T/8 No control Control

  24. Results (cont.) • Plane 8, t=3T/8 No control Control

  25. Results (cont.) • Plane 8, t=4T/8 No control Control

  26. Results (cont.) • Plane 8, t=5T/8 No control Control

  27. Results (cont.) • Plane 8, t=6T/8 No control Control

  28. Results (cont.) • Plane 8, t=7T/8 No control Control

  29. Results (cont.) • Plane 9, t=0 No control Control

  30. Results (cont.) • Plane 9, t=T/8 No control Control

  31. Results (cont.) • Plane 9, t=2T/8 No control Control

  32. Results (cont.) • Planes B and C, control

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

  34. Flow animation for Treft planes

  35. Plane B Circulation variation over one cycle Plane A Plane B Plane A Plane C Plane D

  36. Plane D Circulation Variation (cont.) • Plane C

  37. Pressure ports location Spanwise blowing nozzles

  38. Full flap ESM Pressure profiles @ 13 AOA for Station 3 • Half flap

  39. Full flap ESM Pressure profiles @ 13 AOA for Station 4 • Half flap

  40. Full flap ESM Pressure profiles @ 13 AOA for Station 5 • Half flap

  41. Full flap ESM Pressure profiles @ 13 AOA for Station C • Half flap

  42. Stations 5-7 Stations 8-10 Pressure distributions for α=130.

  43. Stations 5-7 Stations 8-10 Pressure distributions for α=170.

  44. Conclusions WITH ACTUATION: • Dual vortical patterns are activated and periodically emerge downstream • Vortical patterns are managed over the wing • Suction increases with control • Oscillating mini-flaps and pulsed jets equally effective • Flow is better organized • Steady point spanwise blowing has potential

  45. Future Work • Study effect of sweep with new model • Explore the frequency domain • Identify local “3-D actuators” to control these 3-D flow fields • Aim at controlling forces and moments

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