airfoil design
TRANSCRIPT
03 May, 2004 1DUWIND, section Wind Energy, Faculty CiTG
Design of Airfoils for Wind Turbine Blades
Ruud van Rooij([email protected])
Nando Timmer
Delft University of TechnologyThe Netherlands
03 May, 2004 2DUWIND, section Wind Energy, Faculty CiTG
Delft University of Technology13200 Bsc+ Msc students, 4750 employees
Delft University Wind Energy Research Institute(Coordinator: Section Wind Energy)
Faculties:• Civil Engineering and Geosciences (Wind Energy, Offshore)
http://www.windenergy.citg.tudelft.nl/home/flash/index.html
• Information Technology and Systems (Electrical group)
• Design, Engineering and Production (Systems &Control)
• Aerospace Engineering (Aero, Aeroelastics)
03 May, 2004 3DUWIND, section Wind Energy, Faculty CiTG
Section Wind Energy (Civil Engineering and Geosciences => Aerospace Engineering)
Aerodynamic research
- Facilities
open-jetwind tunnel research wind turbine
low speed wind-tunnel
03 May, 2004 4DUWIND, section Wind Energy, Faculty CiTG
Contents
• Background
• Design goals HAWT airfoils
• Design approach• Performance comparison
• Airfoil testing
• Effect on wind turbine power Cp
• Overview HAWT airfoils
03 May, 2004 5DUWIND, section Wind Energy, Faculty CiTG
Background
Operational area
High Cp80% of Energy
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0.0 5.0 10.0 15.0 20.0 25.0
W inds speed (m /s)
Pow er
Variable RPMControl: Power restriction
High max. L/DAirfoil: Max. lift considerations
03 May, 2004 6DUWIND, section Wind Energy, Faculty CiTG
Background
Blade geometry
- High max. L/D- Insensitive to
roughness- Similar design
angle
Airfoil:
- High max. lift(Rot. Effects)
No Aerodynamicdemands
Outboard: t/= .15-18
Mid span: t/= .25
Inboard: t/> .30
Structural:
Transition piece
03 May, 2004 7DUWIND, section Wind Energy, Faculty CiTG
Background
Effect of rotation
RFOIL code
• Integral boundary layer eq.
• Extended for radial flow• Radial equations• Cross flow profile
parameter is c/r(= local solidity)
-0.50
0.00
0.50
1.00
1.50
2.00
2.50
-5.0 0.0 5.0 10.0 15.0 20.0 25.0
Angle (deg.)
cl
DU 91-W2-250Re = 3.0x10e6
2d
mid-span
inboard
Stall delay
03 May, 2004 8DUWIND, section Wind Energy, Faculty CiTG
Design goals HAWT airfoilssteady
Low noise
.21 >.28 - .21> .28Thickness-to-chord ratio
High maximum lift-to-drag ratio
Structural demands
Geometric compatibility
Insensitivity to roughness
Low max. and benign post stall
03 May, 2004 9DUWIND, section Wind Energy, Faculty CiTG
Design approach(example DU 91-W2-250)
DU 91-W2-250
NACA 63-425
Main features
S-Tail => Aft-loading
Small upper surface thickness => reduced roughness sensitivity
03 May, 2004 10DUWIND, section Wind Energy, Faculty CiTG
Design approach(pressure distributions DU 91-W2-250, Re = 3.0x106)
- 4. 0
- 3. 0
- 2. 0
- 1. 0
0. 0
1. 00.0 0.2 0.4 0.6 0.8 1.0x/c
Cp
Separation
Aft-loading
TransitionAlpha= 0.0o
7.0o
11.0o
Low roughness sensitivity=> Transition at nose for Cl_max
Low drag=> Aft transition at Cl_design
03 May, 2004 11DUWIND, section Wind Energy, Faculty CiTG
-0.50
0.00
0.50
1.00
1.50
0 50 100 150cl/cd
cl
-0.50
0.00
0.50
1.00
1.50
-5.0 0.0 5.0 10.0 15.0 20.0Angle (deg.)
cl
DU 91-W2-250
NACA 63-425Re = 3.0x106
Airfoil design(2d performance)
Design lift
Measurements at LST-TU Delft: Clean
03 May, 2004 12DUWIND, section Wind Energy, Faculty CiTG
-0.50
0.00
0.50
1.00
1.50
0 30 60 90cl/cd
cl
-0.50
0.00
0.50
1.00
1.50
-5.0 0.0 5.0 10.0 15.0 20.0Angle (deg.)
cl
DU 91-W2-250
NACA 63-425Re = 3.0x106
Airfoil design(2d performance)
Design lift
Measurements at LST-TU Delft: Roughness simulatedZZ-Tape at 5% u.s.
03 May, 2004 13DUWIND, section Wind Energy, Faculty CiTG
Airfoil testing(Low speed low turbulence tunnel)
Test section size 1.80 x 1.25 mMaximum speed 120 m/sTurbulence level 0.015% at 10 m/s
0.07% at 70 m/s
Test section
03 May, 2004 14DUWIND, section Wind Energy, Faculty CiTG
Airfoil testing(effect of leading edge thickness)
-0.4
0
0.4
0.8
1.2
1.6
-5 0 5 10 15 20 25 30 35 40
angle of attack (degrees)
Lift
coef
ficie
nt
Re=1.0x106
DU 97-W-300
DU 96-W-180
03 May, 2004 15DUWIND, section Wind Energy, Faculty CiTG
Airfoil testing(effect of high Reynolds numbers)
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0 5 10Re x10-6
0
20
40
60
80
100
120
0 5 10Re x10-6
Clean
Zigzag tape 0.4 mm
Carborundum 60
Airfoil: DU 97-W-300Mod
(Cl/Cd)max Cl,max
03 May, 2004 16DUWIND, section Wind Energy, Faculty CiTG
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
Airfoil testing(360 degrees)
03 May, 2004 17DUWIND, section Wind Energy, Faculty CiTG
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
Airfoil testing(360 degrees)
α=24o
03 May, 2004 18DUWIND, section Wind Energy, Faculty CiTG
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
Airfoil testing(360 degrees)
α= 40o
Cl= 1.145
03 May, 2004 19DUWIND, section Wind Energy, Faculty CiTG
Airfoil testing(360 degrees)
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
α=90o
Cl= 0.10 Cd= 1.914
03 May, 2004 20DUWIND, section Wind Energy, Faculty CiTG
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
Airfoil testing(360 degrees)
α= 160o
Cl= -.627
03 May, 2004 21DUWIND, section Wind Energy, Faculty CiTG
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
Airfoil testing(360 degrees)
α= 194o
Cl= 0.541
03 May, 2004 22DUWIND, section Wind Energy, Faculty CiTG
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
Airfoil testing(360 degrees)
α= 224o
Cl= 0.811
03 May, 2004 23DUWIND, section Wind Energy, Faculty CiTG
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
Airfoil testing(360 degrees)
α= 270o
Cl= -0.11 Cd= 1.832
03 May, 2004 24DUWIND, section Wind Energy, Faculty CiTG
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
-50 0 50 100 150 200 250 300 350 400
angle of attack
Cl, Cd
DU 96-W-180
Re=700,000
Airfoil testing(360 degrees)
α= 316o
Cl=- 0.971
03 May, 2004 25DUWIND, section Wind Energy, Faculty CiTG
Airfoil testing (aerodynamic devices)
• Stall strips Ø 1.2 mm
DU 93-W-210 R = 2.0x106
-1.0
-0.5
0.0
0.5
1.0
1.5
0.00 0.01 0.02 0.03cd
cl
-1.0
-0.5
0.0
0.5
1.0
1.5
-10 0 10 20α ( o)
cl
no trip wire
wire at 0.5%c l.s.
wire at 0.25%c l.s.
03 May, 2004 26DUWIND, section Wind Energy, Faculty CiTG
-0.4
0.0
0.4
0.8
1.2
1.6
2.0
0.0 30.0 60.0 90.0 120.0Cl/Cd
Cl
-0.4
0.0
0.4
0.8
1.2
1.6
2.0
-5.0 0.0 5.0 10.0 15.0 20.0 25.0Alpha (deg.)
Cl
VG at x/c= 0.2VG at x/c= 0.3Clean
DU 91-W2-250Re = 2.0x106
Airfoil testing (aerodynamic devices)
• Vortex generators
03 May, 2004 27DUWIND, section Wind Energy, Faculty CiTG
Effect on wind turbine performance(2d stationary performance)
Calculated optimal element performance at mid-span for TSR= 7.5
ZZ-tape 5% u.s.
CpLoadingCp_elem“Static load”Cl_max*c
L/D-maxc/RClean
-5.1%8%.532.155600.135DU 91-W2-250
-0.24%6%.560.1521190.119NACA 63-425
.212
0.143
0.149
.503
.561
.56
-10.2%48%390.212NACA 63-425
0%0%1250.105DU 91-W2-250
-0.06%4%1220.106AH 93-W-257
* “Static load” reference based on 1 year gust for fixed pitch blades
03 May, 2004 28DUWIND, section Wind Energy, Faculty CiTG
0.50
0.51
0.52
0.53
0.54
0.55
0.56
0.57
0 20 40 60 80 100 120 140max. L/D
local Aero Cp
Effect on wind turbine performance (2d stationary performance)
25% thick airfoil class (mid-span for TSR= 7.5)
“Rough”
DU 91-W2-250
-5%
NACA 63-425
-10%
03 May, 2004 29DUWIND, section Wind Energy, Faculty CiTG
Overview of HAWT airfoils
General aviation airfoils• NACA 63-4xx and NACA 63-6xx series• NACA 64-4xx
Dedicated airfoils• S8xx series (NREL, USA)
• FFA W-xxx (FOI, Sweden)
• Risø-A1-xxx (also B, P-series, Risø, Denmark)
• DU xx-W-xxx (Delft, Netherlands)
03 May, 2004 30DUWIND, section Wind Energy, Faculty CiTG
Overview of HAWT airfoils
• Overview of DU-airfoils and users
GE-Wind, REpower, Dewind, Suzlon, Gamesa, LM Glasfiber, NOI Rotortechnik, Fuhrlander, Pfleiderer, EUROS, NEG Micon, Umoe blades, Ecotecnia ……..
DU 97DU 97--WW--300300DU 96DU 96--WW--180180
DU 95DU 95--WW--180180
DU 93DU 93--WW--210210
DU 00DU 00--WW--212212DU 00DU 00--WW--350350
DU 91DU 91--W2W2--250250
03 May, 2004 31DUWIND, section Wind Energy, Faculty CiTG
Next steps:
Extending to all operational situations :
• Measurements => “high” Reynolds number=> chart unsteady behavior of DU airfoils
New airfoil designs :
• Very thick airfoils for lightweight blades
• Control of rpm only => Low TSRLow Cl-max, benign stall
=> High TSRLow drag
• Aero-elastic tailoring => Dynamic airfoil design(Probably low Cl-max)