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REVOLUTIONARY AERODYNAMICS The Sinha-Deturbulator

REVOLUTIONARY AERODYNAMICS The Sinha-Deturbulator. Sumon K. Sinha , Ph.D., P.E , SINHATECH, 3607 Lyles Drive Oxford, Mississippi www.sinhatech.com sumon@sinhatech.com 662-234-6248/ 662-801-6248. TRADITIONAL AERODYNAMICS for Maximizing L/D. Maintain Laminar Flow

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REVOLUTIONARY AERODYNAMICS The Sinha-Deturbulator

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  1. REVOLUTIONARY AERODYNAMICSThe Sinha-Deturbulator Sumon K. Sinha, Ph.D., P.E, SINHATECH, 3607 Lyles Drive Oxford, Mississippi www.sinhatech.com sumon@sinhatech.com 662-234-6248/ 662-801-6248

  2. TRADITIONAL AERODYNAMICS for Maximizing L/D • Maintain Laminar Flow • Avoid Boundary Layer Separation • Maintain Elliptical Spanwise Lift Distribution

  3. 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?

  4. Modified Boundary Layer (Thickness Exaggerated) Unmodified Velocity Profile Deturbulator Modified Velocity Profile Airfoil SLIP LAYER: Deturbulator Stabilized ViscousSub-layer with slow Reversed Flow negates Skin Friction Drag and Speeds up Freestream Flow The Sinha-Deturbulator Approach

  5. 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

  6. Boundary Layer Velocity Profiles Showing Effect of Deturbulation

  7. 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 S 50-100m 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)

  8. FLOW-FCSD INTERACTION • BEST INTERACTION where p/x = 0 • FCSD passes oscillation without damping attheInteraction frequency : • f = U/s • Attenuates other frequencies • This stabilizes the shear layer and mitigates turbulent dissipation

  9. 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 θ = 90º from stagnation (From: Sinha and Wang, 1999, AIAA Paper 99-0923) With Interaction Without Interaction INTERACTION FREQUENCY f = U/s

  10. TESTS ON NLF 0414F WING AFW or FCSD BL-Mouse Global GT-3 Trainer

  11. Transition from AFW to FCSD 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 AFW TRIPPED FLOW w FCSD GT-3 WING BOTTOM VEL PROFILES @ 0.8C

  12. DETURBULATOR CLOSE UP & SURFACE OIL FLOW PATTERNS LSB TRANSITION ATTACHED TURBULENT FLOW FCSD MODIFIED SLIP LAYER CLOSE UP OF FCSD

  13. 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

  14. CL change 0.25 to 0.62 CD change from 0.014 to 0.007 L/D change 17 to 89

  15. SKIN FRICTION REDUCTION

  16. Automobile & Truck Drag Reduction: Increased Highway miles/gallon Stagnant Wake

  17. 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

  18. Minivan Gas Mileage Increase

  19. Sink Rates with Modified Full Span FCSD Treatment

  20. L/D Improvement with Modified Full Span FCSD Treatment

  21. 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% (JohnsonTests 2006) • Max Sailplane L/D increase 30% • Max Section L/D increase (Low-Re) ~ 400%

  22. 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

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

  24. QUESTIONS ?

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