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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 Experimental tools (PIV, pressure scanners, 7-hole probes)
Results:1. Aerodynamics of swept wings2. Flow Control at high alpha3. CONTROL SEPARATED FLOW
(NOT SEPARATION)4. 10 4 < Re < 10 6
Conclusions
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.
Vorticity Rolling over Swept Leading Edges
Sweep> 500 Sweep~450
Sweep~400 Sweep~400
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)
Yaniktepe and Rockwell
Sweep angle 38.7º for 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
Facilities and models
VA Tech Stability Wind Tunnel
U∞=40-60 m/s Re≈1,200,000
44” span diamond-planform wing
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
Wind Tunnel Model
Model is hollow.
Leading edge slot for pulsing jet
8” span diamond wing
Flow control supplied at inboard half of wing
Facilities and models(cont.)
planes z/c z/b
1 0.068 0.092
2 0.156 0.209
3 0.249 0.334
4 0.340 0.456
5 0.417 0.559
6 0.467 0.626
7 0.531 0.711
8 0.581 0.778
9 0.644 0.863
10 0.694 0.930
planes x/c
A 0.28
B 0.513
C 0.746
D 1.086
Data acquisition with enhanced time and space resolution ( > 1000 fps)Image Pre-Processing and Enhancement to Increase signal qualityVelocity Evaluation Methodology with accuracy better than 0.05 pixels and space resolution in the order of 4 pixels
Sneak Preview of Our DPIV System
Time-Resolved DPIV
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
Actuation Time instants of pulsed jet(a)
(b)
(c)
PIV Results Velocity vectors and vorticity contours
along Plane D
no control control
PIV results (cont.) Planes 2(z/b= 0.209) and 3
(z/b= 0.334) with actuation.
Plane 2 Plane 3
Results (cont.) Plane A, control, t=0,t=T/8
Results (cont.) Plane A, control, 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 8, t=0
No control Control
Results (cont.) Plane 8, t=T/8
No control Control
Results (cont.) Plane 8, t=2T/8
No control Control
Results (cont.) Plane 8, t=3T/8
No control Control
Results (cont.) Plane 8, t=4T/8
No control Control
Results (cont.) Plane 8, t=5T/8
No control Control
Results (cont.) Plane 8, t=6T/8
No control Control
Results (cont.) Plane 8, t=7T/8
No control Control
Results (cont.) Plane 9, t=0
No control Control
Results (cont.) Plane 9, t=T/8
No control Control
Results (cont.) Plane 9, t=2T/8
No control Control
Results (cont.) Planes B and C, control
Results (cont.) Plane D, no control and control
Flow animation for Treft planes
Circulation variation over one cycle
Plane A Plane B
Plane B
Plane A
Plane C
Plane D
Circulation Variation (cont.)
Plane C Plane D
Pressure ports location
Spanwise blowing nozzles
ESM Pressure profiles @ 13 AOA for Station 3
Half flap Full flap
ESM Pressure profiles @ 13 AOA for Station 4
Half flap Full flap
ESM Pressure profiles @ 13 AOA for Station 5
Half flap Full flap
ESM Pressure profiles @ 13 AOA for Station C
Half flap Full flap
Pressure distributions for α=130.
Stations 5-7 Stations 8-10
Pressure distributions for α=170.
Stations 5-7 Stations 8-10
ConclusionsWITH 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
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