Flow Control over Swept Edges Demetri Telionis Dept. of Engineering Science and Mechanics.
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Flow Control over Swept Edges Demetri Telionis Dept. of Engineering Science and Mechanics
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Transcript of Flow Control over Swept Edges Demetri Telionis Dept. of Engineering Science and Mechanics.
Flow Control over Swept Edges
Demetri Telionis
Dept. of Engineering Science and Mechanics
Flow Control Team
P. Vlachos J. Rullan J. Gibbs
Sharp Leading and Trailing Edges
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
x/c
Cp
40°30°25°20°15°10°
Pressure coefficient distribution at different angles of attack. No actuation.
20 40 60 80 100 120 140 160 180 2000
500
1000
1500
2000
2500
Hz
Pow
er S
pect
rum
40° Pk: 25.5 - 51 30° Pk::34.75 - 69.525° Pk: 42.5 - 85
20 40 60 80 100 120 140 160 180 2000
50
100
150
200
250
Hz
Pow
er S
pect
rum
20°..Pk: 56 15° Pk: :6610° Pk: N/A
Power Spectra of Wake Velocity
Normal force coefficient variation with excitation frequency. Angle of attack: 20; leading edge flap actuation; trailing edge flap actuation.
Strouhal number variation with excitation frequency. Angle of attack: 20; leading edge flap actuation; trailing edge flap actuation.
Normal force coefficient variation with excitation frequency. Angle of attack:15; leading edge flap actuation.
Strouhal number variation with excitation frequency. Angle of attack: 15; leading edge flap actuation.
Normal force coefficient variation with excitation frequency. Angle of attack:10;leading edge flap actuation.
Strouhal number variation with excitation frequency. Angle of attack: 10;leading edge flap actuation.
20 40 60 80 100 120 140 160 180 2000
200
400
600
800
1000
1200
Hz
Pow
er S
pect
rum
Fa=0 Pk: 34.75 - 69.5
Fa=72.25 Pk: 72.25 - 35.5
20 40 60 80 100 120 140 160 180 2000
100
200
300
400
500
600
700
800
Hz
Pow
er S
pect
rum
Fa=0 Pk: 42.75 - 85.5
Fa=74.5 Pk: 74.5 - 27.5
PSD of Pitot 3 at excitation |F|=2.06. Angle of attack 30
PSD of Pitot 3 at excitation |F|=1.75.Angle of attack 25. Pk: peaks.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
-1.5
-1
-0.5
0
0.5
1
x/c
Cp
|F|=0 Cn : -0.573
|F|=0.5 Cn : -0.770
|F|=0.77 Cn : -0.996
|F|=1 Cn : -0.950
|F|=1.5 Cn : -0.954
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
-2
-1.5
-1
-0.5
0
0.5
1
x/c
Cp
F=0 Cn : -0.632 F=47.5 Cn : -0.792F=90 Cn :-0.678 F=105 Cn : -0.719
Pressure coefficient distribution for controlled case. Angle of attack 10. Leading edge excitation.
Pressure coefficient distribution forcontrolled case. Angle of attack 15. Leadingedge excitation.
Vorticity Rolling over Swept Leading Edges
Sweep> 500 Sweep~450
Sweep~400 Sweep~400
Background (cont.) Low-sweep edges stall like *unswept edges or *highly-swept edges
Dual vortex structures observed over an edge 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, 42 degrees swept edge
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, 40 degrees swept edge
Flow control supplied at inboard half model
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
ESM Pressure profiles @ 13 AOA for Station 3
Half flap Full flap
ESM Pressure profiles @ 13 AOA for Station 4
Half flap Full flap
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
