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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
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Flow Control Team P. VlachosJ. RullanJ. Gibbs
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Overview Background Facilities and models Experimental tools (PIV, pressure scanners, 7-hole probes) Results: 1.Aerodynamics of swept wings 2.Flow Control at high alpha 3.CONTROL SEPARATED FLOW (NOT SEPARATION) 4.10 4 < Re < 10 6 Conclusions
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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.
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Vorticity Rolling over Swept Leading Edges Sweep> 50 0 Sweep~45 0 Sweep~40 0
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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)
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Yaniktepe and Rockwell Sweep angle 38.7 º 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
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Facilities and models VA Tech Stability Wind Tunnel U ∞ =40-60 m/s Re≈1,200,000 44” span diamond- planform wing
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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
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Wind Tunnel Model Model is hollow. Leading edge slot for pulsing jet 8” span diamond wing Flow control supplied at inboard half of wing
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Facilities and models(cont.) planesz/cz/b 10.0680.092 20.1560.209 30.2490.334 40.3400.456 50.4170.559 60.4670.626 70.5310.711 80.5810.778 90.6440.863 100.6940.930 planesx/c A0.28 B0.513 C0.746 D1.086
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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 Sneak Preview of Our DPIV System Time-Resolved DPIV
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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
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Actuation Time instants of pulsed jet (a) (b) (c)
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PIV Results Velocity vectors and vorticity contours along Plane D no controlcontrol
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PIV results (cont.) Planes 2(z/b= 0.209) and 3 (z/b= 0.334) with actuation. Plane 2 Plane 3
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Results (cont.) Plane A, control, t=0,t=T/8
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Results (cont.) Plane A, control, t=2T/8,t=3T/8
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Results (cont.) Plane A, control, t=4T/8,t=5T/8
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Results (cont.) Plane A, control, t=6T/8,t=7T/8
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Results (cont.) Plane 8, t=0 No controlControl
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Results (cont.) Plane 8, t=T/8 No controlControl
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Results (cont.) Plane 8, t=2T/8 No controlControl
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Results (cont.) Plane 8, t=3T/8 No controlControl
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Results (cont.) Plane 8, t=4T/8 No controlControl
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Results (cont.) Plane 8, t=5T/8 No controlControl
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Results (cont.) Plane 8, t=6T/8 No controlControl
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Results (cont.) Plane 8, t=7T/8 No controlControl
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Results (cont.) Plane 9, t=0 No controlControl
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Results (cont.) Plane 9, t=T/8 No controlControl
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Results (cont.) Plane 9, t=2T/8 No controlControl
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Results (cont.) Planes B and C, control
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Results (cont.) Plane D, no control and control
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Flow animation for Treft planes
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Circulation variation over one cycle Plane A Plane B Plane A Plane C Plane D
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Circulation Variation (cont.) Plane C Plane D
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Pressure ports location Spanwise blowing nozzles
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ESM Pressure profiles @ 13 AOA for Station 3 Half flap Full flap
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ESM Pressure profiles @ 13 AOA for Station 4 Half flap Full flap
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ESM Pressure profiles @ 13 AOA for Station 5 Half flap Full flap
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ESM Pressure profiles @ 13 AOA for Station C Half flap Full flap
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Pressure distributions for α=13 0. Stations 5-7 Stations 8-10
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Pressure distributions for α=17 0. Stations 5-7 Stations 8-10
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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
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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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