REVOLUTIONARY AERODYNAMICS The Sinha-Deturbulator Sumon K. Sinha, Ph.D., P.E, SINHATECH, 3607 Lyles Drive Oxford, Mississippi www.sinhatech.com [email protected] 662-234-6248/ 662-801-6248
Download ReportTranscript REVOLUTIONARY AERODYNAMICS The Sinha-Deturbulator Sumon K. Sinha, Ph.D., P.E, SINHATECH, 3607 Lyles Drive Oxford, Mississippi www.sinhatech.com [email protected] 662-234-6248/ 662-801-6248
REVOLUTIONARY AERODYNAMICS The Sinha-Deturbulator Sumon K. Sinha, Ph.D., P.E, SINHATECH, 3607 Lyles Drive Oxford, Mississippi www.sinhatech.com [email protected] 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? The Sinha-Deturbulator Approach Unmodified Velocity Profile Modified Boundary Layer (Thickness Exaggerated) Deturbulator Modified Velocity Profile Airfoil SLIP LAYER: Deturbulator Stabilized Viscous Sub-layer with slow Reversed Flow negates Skin Friction Drag and Speeds up Freestream Flow HOW THE SINHADETURBULATOR INCREASES LIFT AND REDUCES DRAG Laminar Boundary Layer Low Skin Friction Transition to Turbulent flow Base Airfoil Turbulent Boundary Layer High Skin Friction Marginally Separated Boundary Layer Alters “Virtual” Shape of Airfoil; Increases Lift Coefficient Airfoil with Deturbulator Thickness of Deturbulator Tape encourages Marginal Separation Dynamic Flow-FlexibleSurface interaction on Deturbulator maintains nearly stagnant regions of marginal separation Deturbulator attenuates Turbulent Mixing Keeps separated regions nearly stagnant Almost Zero Skin Friction (Lower than in Laminar Flow) Boundary Layer Velocity Profiles Showing Effect of Deturbulation 0.07 Mean vel 80cFCSD10MV 0.06 0.05 Rms vel 80cFCSD10MV Y/C 0.04 Mean Vel 80cCW 0.03 0.02 Rms vel 80c-CW 0.01 0 0 0.1 0.2 0.3 0.4 0.5 0.6 u/u infinity 0.7 0.8 0.9 1 1.1 SINHA FLEXIBLE COMPOSITE SURFACE DETURBULATOR (FCSD) Boundary Layer Flow High Strips or Ridges Flexible Membrane 6m thick Fundamental Flexural Vibration Mode of Membrane Membrane Tension Shown (Amplitude 0.1 m) Wing or other aerodynamic body S Low Strips as needed to fix flexural damping 50-100m Substrate Base glued to aerodynamic surface 10-50m thick Air-Gap (Membrane Substrate) FLOW-FCSD INTERACTION Free stream U/ t v(u/ y)y=0 Flow of pressure fluctuations p/ x 0 p/ x 0 p/ x 0 BEST INTERACTION where p/x = 0 • FCSD passes oscillation without damping at the Interaction SINHA-FCS (Membrane Oscillation velocity v) frequency : Separation point Separated Shear Layer (Oscillates due to fluctuations) f = U/s Attenuates other frequencies •This stabilizes the shear layer and mitigates turbulent dissipation With Interaction Without Interaction INTERACTION FREQUENCY f = U/s 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 990923) 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 FCSD CLEAN WING TRIPPED FLOW w FCSD GT-3 WING BOTTOM VEL PROFILES @ 0.8C AFW Boundary Layer Measurement BL Probe 0.90c, Upper Surface, , WS115, Global GT-3 109 KIAS, Palt 2000 ft, 88 F 0.0 0.0 Average 109 KIAS-Clean Wing 0.0 Avg 109 KIAS FCSD/FPC Y/C 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.4 0.6 0.8 u/Uinfinity 1.0 1.2 1.4 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 CL change 0.25 to 0.62 CD change from 0.014 to 0.007 -1.5 L/D change 17 to 89 Cp -1 -0.5 0 0 10 20 30 40 50 60 X/C ( percentage of chord) 70 Clean Wing Suct Side Press-11/19/04 0.5 Suction Side Pr dist w new FCSD-11/20/04 Pressure Dist Pressure Side 1 80 90 100 SKIN FRICTION REDUCTION Suction Surface Cf Distribution Wortmann 53 inch Std Cirrus Airfoil (Re 300,000 in Sinhatech Wind Tunnel) Cf (Tau-wall/(Rho-Uinf^2/2)) 0.2 Cf-Clean Wing Measured Cf-FCSD 0.15 0.1 0.05 0 0 20 40 60 80 -0.05 -0.1 Position on Chord (X/C) % 100 120 Automobile & Truck Drag Reduction: Increased Highway miles/gallon FLOW WITHOUT TREATMENT FLOW WITH TREATMENT Deturbulator Turbulent Eddies Vehicle or Bluff Body Stagnant Wake Fig 2 Method of Reducing Drag of a Bluff Body such as an Automobile with Deturbulators Mean and RMS Velocity Fluctuations Behind Truck Cab RMS Velocity Fluctuations Behind Cab height above ground / height of Cab Mean Velocities Behind Truck Cab 1.6 Normalized Height (h/h-cab) 1.4 1.2 1 0.8 0.6 Mean Velocity (Untreated) Mean Velocity Deturbulated 0.4 0.2 1.6 1.4 1.2 1 0.8 0.6 RMS Velocity fluctuations Untreated 0.4 RMS Velocity Fluctuations Deturbulated 0.2 0 0 0 0.2 0.4 0.6 0.8 1 1.2 Normalized Mean Velocity (u/U-freestream) 1.4 1.6 0 0.005 0.01 0.015 0.02 0.025 u-rms-fluctuations / U-freestream Deturbulator Reduces Mean and Fluctuation Velocities (h/h-cab 0.5 to1.2). Confirmation that wake stagnates Minivan Gas Mileage Increase 2000 Honda Odyssey Average Highway Gas Mileage 32 Miles Per Gallon 31 Control 30 29 Experiment 28 27 26 25 24 Experiment 23 Control Induced Drag Vs Airspeed on a Standard Cirrus sailplane - CW and FCSD - 03/01/05 0.03 Clean Wing FCSD 60% FCSD full span 0.025 CDi 0.02 0.015 0.01 0.005 0 0 10 20 30 40 Airspeed (m/s) 50 60 Sink Rates with Modified Full Span FCSD Treatment Std. Cirrus #60 Polar Average of 10/12/05 & 10/8/05 800 700 Sink Rate (fpm) 600 500 400 300 200 100 0 40 50 60 70 80 90 100 Airspeed (kts) Baseline Average 10/12 & 10/8 Poly. (Baseline) 110 L/D Improvement with Modified Full Span FCSD Treatment 80 40 70 35 60 30 50 25 40 20 30 15 20 10 10 L/D 45 5 0 0 40 50 60 70 80 90 100 Airspeed (kts) Average 10/12 & 10/8 Baseline % Chg Poly. (Baseline) -10 110 Percent Change Std. Cirrus #60 L/D Average of 10/12/05 & 10/8/05 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 Consistency Robustness Integration Version – 2 of the Deturbulator solves performance degradation due to moisture. Verified on automobiles. Sailplane test results pending with Wing at the Design stage ACKNOWLEDGEMENTS National Science Foundation NASA Oxford Aero Equipment Global Aircraft Robert Williams DGA QUESTIONS ?