revolutionary aerodynamics the sinha-deturbulator
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REVOLUTIONARY AERODYNAMICS
The Sinha-DeturbulatorSumon K. Sinha, Ph.D., P.E,
SINHATECH, 3607 Lyles Drive
Oxford, Mississippiwww.sinhatech.com
sumon@sinhatech.com 662-234-6248/ 662-801-6248
TRADITIONAL AERODYNAMICS for Maximizing L/D
Maintain Laminar Flow Avoid Boundary Layer Separation Maintain Elliptical Spanwise Lift
Distribution
MOTIVATION
Highest L/D is for Sailplanes (70 for AR of 33 with flaps, 48 for AR of 22 without flaps)
L/D Restricted by Limits of Laminar Flow Can we do better than Laminar
Flow?
Modified Boundary Layer (Thickness Exaggerated)
Deturbulator Modified Velocity Profile
Unmodified Velocity Profile
SLIP LAYER: Deturbulator Stabilized
Viscous Sub-layer with slow Reversed Flow negates Skin Friction Drag and Speeds up Freestream Flow
Airfoil
The Sinha-Deturbulator Approach
Base Airfoil
Airfoil with Deturbulator
Transition to Turbulent flow
Turbulent Boundary LayerHigh Skin Friction
Laminar Boundary LayerLow Skin Friction
Marginally Separated Boundary Layer Alters “Virtual” Shape of Airfoil; Increases Lift Coefficient
Deturbulator attenuates Turbulent Mixing Keeps separated regions nearly stagnant Almost Zero Skin Friction (Lower than in Laminar Flow)
Thickness of Deturbulator Tape encourages Marginal Separation
Dynamic Flow-Flexible-Surface interaction on Deturbulator maintains nearly stagnant regions of marginal separation
HOW THE SINHA-DETURBULATOR INCREASES
LIFT AND REDUCES DRAG
Boundary Layer Velocity Profiles Showing Effect of Deturbulation
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1
u/u infinity
Y/C
Mean vel 80c-FCSD10MV
Rms vel 80c-FCSD10MV
Mean Vel 80c-CW
Rms vel 80c-CW
SINHA FLEXIBLE COMPOSITE SURFACE DETURBULATOR (FCSD)
Membrane Tension
50-100mS
Boundary Layer Flow
Flexible Membrane 6m thick
Substrate Base glued to aerodynamic surface
High Strips or Ridges
Low Strips as needed to fix flexural damping
Fundamental Flexural Vibration Mode of MembraneShown (Amplitude 0.1 m)
10-50m thick Air-Gap (Membrane Substrate)
Wing or other aerodynamic body
FLOW-FCSD INTERACTION
p/ x 0
p/ x 0
p/ x 0
Free stream U/ t v( u/ y) y=0
SINHA - FCS (Membrane Oscillation velocity v)
Separation point
Separated Shear Layer (Oscillates due to fluctuations)
Flow of pressure fluctuations
BEST INTERACTION where p/x = 0
• FCSD passes oscillation without damping at the
Interaction frequency :
f = U/sAttenuates other frequencies
•This stabilizes the shear layer and mitigates turbulent dissipation
MODIFICATION OF TURBULENCE
BY FLEXIBLE SURFACESPECTRA OF
STREAMWISE VELOCITY FLUCTUATIONS
With (top) and Without (bottom) Flexible-Surface Interaction for Separated Flow over a Cylinder in Crossflow for Re = 150,000, M = 0.05 at θ = 90º from stagnation (From: Sinha and Wang, 1999, AIAA Paper 99-0923)
INTERACTION FREQUENCY f = U/s
With Interaction
Without Interaction
TESTS ON NLF 0414F WING
AFW or FCSD
BL-Mouse
Global GT-3 Trainer
Transition from AFW to FCSD Unexcited AFW
produced a boundary layer profile very similar to the excited AFW.
Difference in percentage drag reduction is minimal.
FCSD Simplifies the manufacturing and installation procedure.
More pragmatic on retrofitting existing aircrafts
CLEAN WING
TRIPPED FLOW w FCSD
AFW
FCSD
GT-3 WING BOTTOM VEL PROFILES @ 0.8C
Boundary Layer MeasurementBL Probe 0.90c, Upper Surface, , WS115, Global GT-3
109 KIAS, Palt 2000 ft, 88 F
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
u/Uinfinity
Y/C
Average 109 KIAS-Clean Wing
Avg 109 KIAS FCSD/FPC
DETURBULATOR CLOSE UP & SURFACE OIL FLOW PATTERNS
LSB TRANSITION ATTACHED TURBULENT FLOW
FCSD MODIFIED SLIP LAYER
CLOSE UP OF FCSD
TESTS ON STANDARD CIRRUS SAILPLANE TO IMPROVE L/D
Drag Pressure Sensors
Gross Weight: 728 lbs
Best L/D: 36 @ 52-kts
Wing Loading: 6.8 lb/ft2 Aspect Ratio: 22.5
Pressure distribution on 2nd. Wind-Tunnel model of 53-Inch Span Section of Standard Cirrus Wing (New FCSD installion on Suction Side Only)-11/20/04
-2
-1.5
-1
-0.5
0
0.5
1
0 10 20 30 40 50 60 70 80 90 100X/C ( percentage of chord)
Cp
Clean Wing Suct Side Press-11/19/04
Suction Side Pr dist w new FCSD-11/20/04
Pressure Dist Pressure Side
CL change 0.25 to 0.62
CD change from 0.014 to 0.007
L/D change 17 to 89
SKIN FRICTION REDUCTION
Suction Surface Cf Distribution Wortmann 53 inch Std Cirrus Airfoil (Re 300,000 in Sinhatech Wind Tunnel)
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0 20 40 60 80 100 120
Position on Chord (X/C) %
Cf (
Tau-w
all/
(Rho-U
inf
2̂/2
))
Cf-Clean Wing Measured Cf-FCSD
Automobile & Truck Drag Reduction: Increased Highway miles/gallon
FLOW WITHOUT TREATMENT
FLOW WITH TREATMENT
Turbulent Eddies
Vehicle or Bluff Body
Deturbulator
Fig 2 Method of Reducing Drag of a Bluff Body such as an Automobile with Deturbulators
Stagnant Wake
Mean and RMS Velocity Fluctuations Behind Truck Cab
Mean Velocities Behind Truck Cab
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Normalized Mean Velocity (u/U-freestream)
Norm
alize
d He
ight
(h/h
-cab
)
Mean Velocity (Untreated)
Mean Velocity Deturbulated
RMS Velocity Fluctuations Behind Cab
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.005 0.01 0.015 0.02 0.025u-rms-fluctuations / U-freestream
heig
ht a
bove
gro
und
/ hei
ght
of C
ab
RMS Velocityfluctuations Untreated
RMS VelocityFluctuationsDeturbulated
Deturbulator Reduces Mean and Fluctuation Velocities (h/h-cab 0.5 to1.2).
Confirmation that wake stagnates
Minivan Gas Mileage Increase
Control
Experiment23
24
25
26
27
28
29
30
31
32
Mile
s P
er G
allo
n
2000 Honda Odyssey Average Highway Gas Mileage
Control
Experiment
Induced Drag Vs Airspeed on a Standard Cirrus sailplane - CW and FCSD - 03/01/05
0
0.005
0.01
0.015
0.02
0.025
0.03
0 10 20 30 40 50 60Airspeed (m/s)
CD
i
Clean WingFCSD 60% FCSD full span
Sink Rates with Modified Full Span FCSD Treatment
Std. Cirrus #60 Polar Average of 10/12/05 & 10/8/05
0
100
200
300
400
500
600
700
800
40 50 60 70 80 90 100 110
Airspeed (kts)
Sin
k R
ate
(fp
m)
Baseline Average 10/12 & 10/8 Poly. (Baseline)
L/D Improvement with Modified Full Span FCSD Treatment
Std. Cirrus #60 L/D Average of 10/12/05 & 10/8/05
0
5
10
15
20
25
30
35
40
45
40 50 60 70 80 90 100 110
Airspeed (kts)
L/D
-10
0
10
20
30
40
50
60
70
80
Percent C
hange
Average 10/12 & 10/8 Baseline % Chg Poly. (Baseline)
SUMMARY OF REVOLUTIONARY FCSD
AERODYNAMICS FCSD Reduces Turbulence Creates “Slip Layer” Reduces Skin Friction Increases Lift Reduces Induced and Parasitic Drag Across
Speed Range. Increased Best Sailplane L/D by 18 % (Johnson
Tests 2006) Max Sailplane L/D increase 30% Max Section L/D increase (Low-Re) ~ 400%
OTHER Important ISSUES
ConsistencyRobustness Integration with Wing at the
Design stage
Version – 2 of the Deturbulator solves performance degradation due to moisture. Verified on automobiles. Sailplane test results pending
ACKNOWLEDGEMENTS
National Science Foundation NASA Oxford Aero Equipment Global Aircraft Robert Williams DGA
QUESTIONS ?
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