REVOLUTIONARY AERODYNAMICS The SinhaDeturbulator

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REVOLUTIONARY AERODYNAMICSThe Sinha-Deturbulator

• Sumon K. Sinha, Ph.D., P.E,
• SINHATECH,
• 3607 Lyles Drive
• Oxford, Mississippi
• www.sinhatech.com
• sumon_at_sinhatech.com 662-234-6248/ 662-801-6248

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TRADITIONAL AERODYNAMICS for Maximizing L/D

• Maintain Laminar Flow
• Avoid Boundary Layer Separation
• Maintain Elliptical Spanwise Lift Distribution

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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?

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The Sinha-Deturbulator Approach
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HOW THE SINHA-DETURBULATOR INCREASES LIFT AND
REDUCES DRAG
Laminar Boundary Layer Low Skin Friction
Thickness of Deturbulator Tape encourages
Marginal Separation Dynamic Flow-Flexible-Surface
interaction on Deturbulator maintains nearly
stagnant regions of marginal separation
Transition to Turbulent flow
Base Airfoil
Turbulent Boundary Layer High 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)
Airfoil with Deturbulator
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Boundary Layer Velocity Profiles Showing Effect
of Deturbulation
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SINHA FLEXIBLE COMPOSITE SURFACE DETURBULATOR
(FCSD)
 
Boundary Layer Flow
High Strips or Ridges
Flexible Membrane ? 6?m thick
Fundamental Flexural Vibration Mode of
Membrane Shown (Amplitude ? 0.1 ?m)
Membrane Tension
50-100?m
S
Wing or other aerodynamic body
Substrate Base glued to aerodynamic surface
Low Strips as needed to fix flexural damping
10-50?m thick Air-Gap (Membrane Substrate)
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FLOW-FCSD INTERACTION

• BEST INTERACTION where ?p/?x 0
• FCSD passes oscillation without damping at the
  Interaction frequency
• f U/s
• Attenuates other frequencies
• This stabilizes the shear layer and mitigates
  turbulent dissipation

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MODIFICATION OF TURBULENCE BY FLEXIBLE
SURFACE SPECTRA 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 ? 90º from stagnation (From Sinha
and Wang, 1999, AIAA Paper 99-0923)
With Interaction
Without Interaction
INTERACTION FREQUENCY f U/s
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TESTS ON NLF 0414F WING
AFW or FCSD
BL-Mouse
Global GT-3 Trainer
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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

FCSD
CLEAN WING
AFW
TRIPPED FLOW w FCSD
GT-3 WING BOTTOM VEL PROFILES _at_ 0.8C
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DETURBULATOR CLOSE UP SURFACE OIL FLOW PATTERNS
LSB TRANSITION
ATTACHED TURBULENT FLOW
FCSD MODIFIED SLIP LAYER
CLOSE UP OF FCSD
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TESTS ON STANDARD CIRRUS SAILPLANE TO IMPROVE L/D
Drag Pressure Sensors
Gross Weight 728 lbs Best L/D 36 _at_
52-kts Wing Loading 6.8 lb/ft2 Aspect
Ratio 22.5
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CL change 0.25 to 0.62 CD change from 0.014 to
0.007 L/D change 17 to 89
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SKIN FRICTION REDUCTION
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Automobile Truck Drag Reduction Increased
Highway miles/gallon
Stagnant Wake
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Mean and RMS Velocity Fluctuations Behind Truck
Cab
Deturbulator Reduces Mean and Fluctuation
Velocities (h/h-cab 0.5 to1.2). Confirmation
that wake stagnates
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Minivan Gas Mileage Increase
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Sink Rates with Modified Full Span FCSD Treatment
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L/D Improvement with Modified Full Span FCSD
Treatment
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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

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OTHER Important ISSUES
Version 2 of the Deturbulator solves
performance degradation due to moisture. Verified
on automobiles. Sailplane test results pending

• Consistency
• Robustness
• Integration with Wing at the Design stage

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ACKNOWLEDGEMENTS

• National Science Foundation
• NASA
• Oxford Aero Equipment
• Global Aircraft
• Robert Williams
• DGA

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• QUESTIONS ?