New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6...
Transcript of New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6...
![Page 1: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/1.jpg)
New winglet for LS6
Winglet aerodynamic design experience
&
Corresponding RANS analysis using TAU (DLR)
Matthieu Scherrer & Stefan Melber-Wilkending (DLR)
![Page 2: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/2.jpg)
Introduction Winglet for LS6 ? Physical aspects at stake for winglet design
Winglet aerodynamic design Winglet concept Parametrical study Final design
Back to back analysis of winglets vs plain tips with TAU-RANS (DLR) Presentation of the computations Local analysis Computed drag & lift analysis
Conclusion
Contents
![Page 3: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/3.jpg)
Introduction
![Page 4: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/4.jpg)
Winglet is a must on all last sailplane Benefits in competition proved over the years,
though not fully catched in theory
LS6a/b Probably the most optimised 15m with plain tips.
Wonderful handling & confort
Existing retrofits LS6c/WL factory WL (similar to LS8)
Piontowsky design for LS6a version (similar to factory LS6-18W)
Darlington design for LS8
Winglets for LS6 ?
![Page 5: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/5.jpg)
Aerodynamic aspects to be considered in winglet design
Expected performance benefit of winglet is small Sailplane are already high AR, low induced drag ships
Even “side effects” to be considered
List of items to be considered in winglet design Effect on induced drag (equivalent AR)
& Additional wetted area
Multipoint design
Effect of winglet on wing tip transition pattern
Trimming drag & winglets
![Page 6: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/6.jpg)
It is reported that re-laminarization due to winglet plays an important role in the benefit on the speed polar Principle sketch
Can CFD catch this phenomenon ?
Change in wing tip transition pattern
tr
![Page 7: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/7.jpg)
Tail loading affects the sailplane wake, hence the induced drag Detectable effect on the benefit brought by winglet
Trimming drag
Wingtlet benefit DCD: -2.21% Wingtlet benefit DCD: -1.72%
![Page 8: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/8.jpg)
Winglet design
![Page 9: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/9.jpg)
Winglet concept
Two extrem sort of existing winglets
Big “shovel” Robustness to sideslip
Plain tip + winglet blade High efficiency winglet
It was choosen to have a high AR blade plus a large transition region
![Page 10: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/10.jpg)
Design parameters
Height/span Retrofit limitation
Chords Reynolds vs wetted area
Sweep angles
Local loading
Dihedrals
Blade angle for wing flexion Transition radius
Twist / toes
Local loading ->3DOF to be optimised
-0.5
-0.25
0
0.25
0.5
0.75
1
1.25
1.5
6.000 6.500 7.000 7.500 8.000
-0.5
-0.25
0
0.25
0.5
0.75
1
1.25
1.5
6.000 6.500 7.000 7.500 8.000
![Page 11: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/11.jpg)
Custom airfoil design Derived from model glider experience
Forward pressure recovery gradient for robustness to separation
Main winglet airfoil design
CL=0.6
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0 0.25 0.5 0.75 1
x/c
Cp
PSU94097 (ref)
MS-Wglt
![Page 12: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/12.jpg)
Parametric study
4DOF study Geometric : Outer wing twist, winglet twist & toe
Aerodynamic : CL (0.2, 0.6, 1.2)
Use of rapid – relatively simple tool Induced drag is computed without wake balancing (AVL)
Viscous drag is locally evaluated along span as function of Cl, based on 2D polars.
Drag figures increment computed with trimming constraint through elevator deflection, for a mid CG.
saiplanesaiplanesaiplanewinglet CLCDCLCDCLCD sailplane trimmed
wingletw/o
sailplane trimmed
wingletw D
![Page 13: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/13.jpg)
Raw results from parametric study
Evolution of winglet benefit vs 4DOF (3 angle & CL)
CL=0.2
CL=0.6
CL=1.2
![Page 14: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/14.jpg)
Multipoint approach
Merit figure to be optimised : weighted polar, according to flight template theory.
“Envelope Flight template”
0 0.5 1 1.5CL
FT
(CL
)
Enveloppe Flight Template
Represents a statistically relevant program of a typical cross country flight. It is used for defining a multipoint cost function :
LLt
L
LD
L
D dCCfC
CC
C
C
range C 2/32/3L
)()(
Ref paper ostiv
![Page 15: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/15.jpg)
Parametric study with multipoint approach
Merit figure to be optimised : weighted polar, according to flight template theory.
![Page 16: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/16.jpg)
Target wing loading approach
Local load along span Local Cl should not exceed the max lift of airfoil
Helps at selecting toe/twist combination among quasi equivalent solutions
Local lift distributions
0
0.25
0.5
0.75
1
1.25
5.5 6 6.5 7 7.5 8
Y
Cl
Local Cl, Ref LS6 (no WL), CL=0.2Local Cl, Ref LS6 (no WL), CL=0.6Local Cl, Ref LS6 (no WL), CL=1.2Local Cl, LS6WL, CL=0.2Local Cl, LS6WL, CL=0.6Local Cl, LS6WL, CL=1.2Local Cl, LS6WL final tw ist/toe, CL=0.2Local Cl, LS6WL final tw ist/toe, CL=0.6Local Cl, LS6WL final tw ist/toe, CL=1.2
![Page 17: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/17.jpg)
Rational for selecting winglets settings
The influence of the toe/twist angle seems low within a quite wide range (for the prediction method used) Typical “flat optimum range : +/-2deg
This is not in line with reported experience in WL design
This must somehow be filtered by some other criteria Local CL available from AVL
Evidence of risk of overloading in the transition region
Practical conclusion Once the winglet exists, most of its effects on induced drag is
settled (i.e. twist optimisation for Cdi is exagerated refinement)
Winglet setting should be sized for controlling viscous drag in extreme cases : intrados laminarity at low CL & extrados corner separation at high CL.
![Page 18: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/18.jpg)
Final winglet geometry
Twist & toe Risk mitigation vs transition region loading
Not absolute optimal for AVL, local minimum
CAD for meshing & milling purpose (Flybiwo)
Swetted/Sref=1
![Page 19: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/19.jpg)
Non-performance sizing aspects
Wing root bending moment
Handling quality
Flutter Measurement of sailplane modes sensitivity to additional masses
planned
![Page 20: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/20.jpg)
Analysis of winglets vs plain tips using TAU-RANS (DLR)
Computation presentation Reference wing winth plain tips
Effect of winglets
![Page 21: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/21.jpg)
CFD for sailplane purpose
Heavy CFD is rapidly developping for aerospace industry
TAU is an unstructured RANS code from DLR, that is used daily at Airbus
Can those developments give interesting results for sailplane design ? A glider is not an airliner !
Ingredient for this test case : 3D aero, laminarity
![Page 22: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/22.jpg)
Geometry & mesh
Half a wing was meshed (symmetrical cases) Around 7.5 E6 points in the meshes
![Page 23: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/23.jpg)
Setting up of computations
A list of 7 points along the speed polar were computed
Computation attempted for 4 conditions (7x4=28 cases) :
Winglet & plain tip geometry
Full turbulent flow & with transition
A list of 7 points along the speed polar were computed Turbulence model : K-w-SST
Transition : Tolmienn-Schlichtting waves & laminar bubble detection (N=11.5)
Elements of computation performance : 1 case = 80h on 40 cores
case CL V (m/s)
1 0.2 56.6
2 0.6 32.7
3 0.8 28.3
4 1.2 23.1
5 1.259 22.6
6 1.308 22.2
7 1.353 21.8
![Page 24: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/24.jpg)
Analysis of winglets vs plain tips using TAU-RANS (DLR)
Computation presentation Reference wing winth plain tips
Effect of winglets
![Page 25: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/25.jpg)
TAU for plain wing tip
Local Cp & transition comparison Comparison with MIAReX extended lifting line
Drag polar comparison Comparison with MIAReX computation & IDAFLIEG measurement
Evaluation of aerodynamic coefficients through two methods : Wing surface integration & far-field analysis
![Page 26: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/26.jpg)
TAU for plain wing tip
Local Cp & transition comparison y/b=0 Comparison with MIAReX extended
lifting line, same CL
Comment General shape reproduced
No laminar bubble modelling for
TAU (with transition computation)
Undersurface at TE not behaving similarly (lam bubble)
Transition prediction differs
![Page 27: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/27.jpg)
TAU for plain wing tip
Local Cp & transition comparison y/b= 0.28 & 0.53 Comparison with MIAReX extended lifting line
![Page 28: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/28.jpg)
TAU for plain wing tip
Local Cp & transition comparison y/b=0.75 & 0.91 Comparison with MIAReX extended lifting line
![Page 29: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/29.jpg)
TAU for plain wing tip
Comparion of transition predictions for CL=0.6 Comparison with MIAReX computation : more fwd transition line
Same definition of Transition point ?
Compatible with comparison of drag values (next slide)
Transition prediction for original wing
TAU vs MIAReX
-0.5
0
0.5
1
1.5
0 1 2 3 4 5 6 7 8y (m)
X T
r
Xtr Miarex - Upper
Xtr Miarex - Lower
Xtr Tau - Upper
Xtr Tau - Lower
![Page 30: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/30.jpg)
TAU for plain wing tip
Results for aerodynamic coefficients
Conclusion : Absolute value from TAU cannot be used with confidence. Back to back analysis necessary :construction of an increment of
performance
Comparison of drag polars
Original wing - Total drag
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055
CD
CL
A/C CD from IDAflieg speed polar
Cxtot - Miarex
CD tot NF Turb - Tau
CD tot NF Lam - Tau
CD tot FF Turb - Tau
CD tot FF Lam - Tau
0. Two references: IDAFLIEG. Polar MIAReX computation (lifting line)
1. Full turbulent result - More drag for the wing alone than for
sailplane as measured by IDAFLIEG. - Difference FarField/Nearfield
1
2. Results with transition - Farfield analysis shows result more
compatible with IDAFLIEG
2
![Page 31: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/31.jpg)
Analysis of winglets vs plain tips using TAU-RANS (DLR)
Computation presentation Reference wing winth plain tips
Effect of winglets
![Page 32: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/32.jpg)
Effect of Winglet in the flowfield
It is possible to “explore” the flowfield in the wake of the wing & winglet
![Page 33: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/33.jpg)
Winglet & wing tip pressure field
Three station where considered to analyse local pressure features
Cut 1
Cut 2
Cut 3
![Page 34: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/34.jpg)
Pressure line near tip for CL=0.2
-1.25
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0 0.25 0.5 0.75 1
x/c
Cp
Plain tip cut 1WL Cut 1WL Cut 2WL Cut 3
Evolution of wing tip pressure field
CL=0.2, V=56.6m/s
Full turbulent solution
![Page 35: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/35.jpg)
Pressure line near tip for CL=0.6
-1.25
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0 0.25 0.5 0.75 1
x/c
Cp
Plain tip cut 1WL Cut 1WL Cut 2WL Cut 3
Winglet & wing tip pressure field
CL=0.6, V=32.7m/s
Full turbulent solution
![Page 36: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/36.jpg)
Pressure line near tip for CL=0.8
-1.5
-1.25
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0 0.25 0.5 0.75 1
x/c
Cp
Plain tip cut 1WL Cut 1WL Cut 2WL Cut 3
Winglet & wing tip pressure field
CL=0.8, V=28.3m/s
Full turbulent solution
![Page 37: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/37.jpg)
Pressure line near tip for CL=1.2
-2.5
-2.25
-2
-1.75
-1.5
-1.25
-1
-0.75
-0.5
-0.25
0
0.25
0.5
0 0.25 0.5 0.75 1x/c
Cp
Plain tip cut 1WL Cut 1WL Cut 2WL Cut 3
Winglet & wing tip pressure field
CL=1.2, V=23.1m/s
Full turbulent solution
![Page 38: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/38.jpg)
Winglet & transition line
Effect of winglet on transion line is represented by CFD
Delay the transition by up to 8% on pressure side
Phenomenon damped over 4% of span
Transition prediction with & w/o winglet
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
6.8 6.9 7 7.1 7.2 7.3 7.4 7.5 7.6
y (m)
X T
r
Xtr Tau - Upper
Xtr Tau - Lower
Tau WL - Upper
Tau WL - Lower
Transition prediction with & w/o winglet
0%
10%
20%
30%
40%
50%
60%
70%
6.8 6.9 7 7.1 7.2 7.3 7.4 7.5
y (m)
X T
r
Xtr Tau - Upper
Xtr Tau - Lower
Tau WL - Upper
Tau WL - Lower
![Page 39: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/39.jpg)
Winglet benefit evaluation
Drag modification brought by winglet
NB : Reliable winglet computation with transition : only CL=0.2 & 0.9, higher CL extrapolated
Effect of winglets
Drag benefit
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-0.0015 -0.001 -0.0005 0 0.0005
DCD
CL
DCD winglet (full turb)
DCD winglet (Transition computation)
Effect of winglets
Relative drag benefit
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-4.00% -3.00% -2.00% -1.00% 0.00% 1.00% 2.00% 3.00%
DCD
CL
DCD winglet (full turb)
DCD winglet (Transition computation)
![Page 40: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/40.jpg)
Winglet benefit evaluation
Pilot perspective
NB : Reliable winglet computation with transition : only CL=0.2 & 0.9, higher CL extrapolated
Effect of winglets - Pilot perspective
-1
-0.5
0
0.5
1
1.5
2
50 100 150 200 250
V (kph) @ 33kg/m²
D L
/D
Increment of L/D due to winglet(full turb)Increment of L/D due to winglet(Transition computation)
0.5
0.75
1
1.25
1.5
70 90 110 130 150 170
V (kph) @ 33kg/m²
Vz (
m/s
)
IDAFLIEG
WL with benefit (full turbulent computation)
WL with benefit (computation with transition effect)
![Page 41: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/41.jpg)
Conclusion
![Page 42: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/42.jpg)
Conclusion
Design of new winglet for LS6 A concept as starting point
Simple tools & pragmatic approach for angle setting
Winglet analysis Use of available method, over a quite large number of
computation cases
Understanding of local aerodynamic of winglet
Documented evaluation of performance modification
Next step : let’s fly those winglets !
![Page 43: New winglet for LS6 · 2011. 5. 11. · Original wing - Total drag 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 CD CL A/C CD from IDAflieg](https://reader034.fdocuments.us/reader034/viewer/2022051916/6008086cfb757612062bfe33/html5/thumbnails/43.jpg)
Special thanks
DLR (TAU code)
Flybiwo (CAD & milling)
Have nice flights !
Questions ?