Design of Airfoils for Wind Turbine Blades

Transcription

Design of Airfoils
for Wind Turbine Blades
Ruud van Rooij
([email protected])
Nando Timmer
Delft University of Technology
The Netherlands
03 May, 2004
DUWIND, section Wind Energy, Faculty CiTG
1
Delft University of Technology
13200 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
2
Section Wind Energy
(Civil Engineering and Geosciences => Aerospace Engineering)
Aerodynamic research
- Facilities
low speed
wind-tunnel
open-jet
wind tunnel
03 May, 2004
research wind turbine
3
Contents
•
Background
•
Design goals HAWT airfoils
•
Design approach
•
03 May, 2004
Performance comparison
•
Airfoil testing
•
Effect on wind turbine power Cp
•
Overview HAWT airfoils
4
Background
Operational area
Control:
1.2
P ow e r
1.0
Variable RPM
Power restriction
High Cp
80% of Energy
0.8
0.6
0.4
0.2
W in ds spe e d (m /s)
0.0
0.0
Airfoil:
03 May, 2004
5.0
10.0
High max. L/D
15.0
20.0
25.0
Max. lift considerations
5
Background
Blade geometry
Structural:
Airfoil:
Outboard: t/= .15-18
- High max. L/D
- Insensitive to
roughness
- Similar design
angle
Mid span: t/= .25
Inboard: t/> .30
Transition piece
03 May, 2004
- High max. lift
(Rot. Effects)
No Aerodynamic
demands
6
Background
Effect of rotation
RFOIL code
• Integral boundary layer eq.
• Extended for radial flow
• Radial equations
• Cross flow profile
Stall delay
2.50
inboard
cl
2.00
mid-span
1.50
2d
1.00
0.50
parameter is c/r
(= local solidity)
03 May, 2004
DU 91-W2-250
Re = 3.0x10e6
0.00
-0.50
-5.0
Angle (deg.)
0.0
5.0
10.0
15.0
20.0
25.0
7
Design goals HAWT airfoils
steady
Thickness-to-chord ratio
> .28
.28 - .21
.21 >
High maximum lift-to-drag ratio
Low max. and benign post stall
Insensitivity to roughness
Low noise
Geometric compatibility
Structural demands
03 May, 2004
8
Design approach
(example DU 91-W2-250)
Main features
Small upper surface thickness
=> reduced roughness sensitivity
NACA 63-425
DU 91-W2-250
03 May, 2004
S-Tail
=> Aft-loading
9
Design approach
(pressure distributions DU 91-W2-250, Re = 3.0x106)
- 4. 0
Low roughness sensitivity
=> Transition at nose for Cl_max
Cp
- 3. 0
11.0o
- 2. 0
- 1. 0
Low drag
=> Aft transition at Cl_design
7.0o
Transition
Alpha= 0.0o
Separation
0. 0
Aft-loading
1. 0
0.0
03 May, 2004
0.2
0.4
0.6
x/c
0.8
1.0
10
Airfoil design
(2d performance)
Measurements at LST-TU Delft: Clean
1.50
1.50
Design lift cl
cl
1.00
1.00
0.50
0.50
0.00
0.00
DU 91-W2-250
Re = 3.0x106
NACA 63-425
-0.50
0
03 May, 2004
50
cl/cd
100
150
-0.50
-5.0
0.0
5.0 10.0 15.0 20.0
Angle (deg.)
11
Airfoil design
(2d performance)
Measurements at LST-TU Delft: Roughness simulated
1.50
ZZ-Tape at 5% u.s.
1.50
cl
Design lift
1.00
1.00
cl
0.50
0.50
0.00
0.00
DU 91-W2-250
Re = 3.0x106
NACA 63-425
-0.50
0
03 May, 2004
30
cl/cd
60
90
-0.50
-5.0
0.0
5.0
10.0
15.0
20.0
Angle (deg.)
12
Airfoil testing
(Low speed low turbulence tunnel)
Test section size 1.80 x 1.25 m
Maximum speed 120 m/s
Turbulence level 0.015% at 10 m/s
0.07% at 70 m/s
Test section
03 May, 2004
13
Airfoil testing
(effect of leading edge thickness)
DU 97-W-300
Lift coefficient
1.6
1.2
DU 96-W-180
0.8
6
Re=1.0x10
0.4
0
-5
0
5
10
15
20
25
30
35
40
angle of attack (degrees)
-0.4
03 May, 2004
14
Airfoil testing
(effect of high Reynolds numbers)
Airfoil: DU 97-W-300Mod
120
1.6
100
1.4
Cl,max
(Cl/Cd)max
80
1.2
60
1.0
40
0.8
Clean
20
Zigzag tape 0.4 mm
0.6
Carborundum 60
0
0.4
0
03 May, 2004
5
Re x10
-6
10
0
5
Re x10-6
10
15
Airfoil testing
(360 degrees)
2.5
Cl, Cd
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
16
Airfoil testing
(360 degrees)
α=24o
2.5
Cl, Cd
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
17
Airfoil testing
(360 degrees)
α= 40o
2.5
Cl= 1.145
Cl, Cd
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
18
Airfoil testing
(360 degrees)
α=90o
2.5
Cl= 0.10 Cd= 1.914
Cl, Cd
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
19
Airfoil testing
(360 degrees)
α= 160o
2.5
Cl= -.627
Cl, Cd
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
20
Airfoil testing
(360 degrees)
α= 194o
2.5
Cl= 0.541
Cl, Cd
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
21
Airfoil testing
(360 degrees)
α= 224o
2.5
Cl, Cd
Cl= 0.811
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
22
Airfoil testing
(360 degrees)
α= 270o
2.5
Cl= -0.11 Cd=
1.832
Cl, Cd
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
23
Airfoil testing
(360 degrees)
α= 316o
2.5
Cl=- 0.971
Cl, Cd
2
1.5
1
0.5
0
-50
0
50
100
150
200
250
300
350
400
-0.5
-1
-1.5
03 May, 2004
DU 96-W-180
Re=700,000
angle of attack
24
Airfoil testing
(aerodynamic devices)
• Stall strips
Ø 1.2 mm
1.5
1.5
cl
cl
1.0
1.0
0.5
0.0
0.00
0.5
DU 93-W-210
R = 2.0x106
0.0
0.01
0.02
cd 0.03
-10
0
-0.5
-0.5
10
o
α ( ) 20
no trip wire
wire at 0.5%c l.s.
-1.0
-1.0
03 May, 2004
wire at 0.25%c l.s.
25
Airfoil testing
(aerodynamic devices)
• Vortex generators
2.0
2.0
Cl
Cl
1.6
1.6
1.2
1.2
0.8
0.8
0.4
0.4
0.0
0.0
DU 91-W 2-250
6
Re = 2.0x10
-0.4
0.0
30.0
60.0
90.0
120.0
-0.4
-5.0
Cl/Cd
03 May, 2004
VG at x/c= 0.2
VG at x/c= 0.3
Clean
0.0
5.0
10.0
15.0
20.0
25.0
Alpha (deg.)
26
Effect on wind turbine performance
(2d stationary performance)
Calculated optimal element performance at mid-span for TSR= 7.5
“Static load”
Cp_elem
Cl_max*c
Clean
c/R
L/D-max
AH 93-W-257
0.106
122
0.149
DU 91-W2-250 0.105
125
0.119
DU 91-W2-250
NACA 63-425
NACA 63-425
Loading
Cp
.56
4%
-0.06%
0.143
.561
0%
0%
119
0.152
.56
6%
-0.24%
0.135
60
.155
.532
8%
-5.1%
0.212
39
.212
.503
48%
-10.2%
ZZ-tape 5% u.s.
* “Static load” reference based on 1 year gust for fixed pitch blades
03 May, 2004
27
Effect on wind turbine performance
(2d stationary performance)
local Aero Cp
25% thick airfoil class (mid-span for TSR= 7.5)
0.57
DU 91-W2-250
0.56
-5%
0.55
0.54
-10%
0.53
0.52
“Rough”
0.51
NACA 63-425
0.50
0
03 May, 2004
20
40
60
80
max. L/D
100
120
140
28
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
29
Overview of HAWT airfoils
• Overview of DU-airfoils and users
DU 95-W-180
DU 96-W-180
DU 00-W-212
DU 91-W2-250
DU 97-W-300
DU 00-W-350
DU 93-W-210
GE-Wind, REpower, Dewind, Suzlon, Gamesa, LM Glasfiber, NOI Rotortechnik,
Fuhrlander, Pfleiderer, EUROS, NEG Micon, Umoe blades, Ecotecnia ……..
03 May, 2004
30
Next steps:
Extending to all operational situations :
•
Measurements
=> “high” Reynolds number
=> chart unsteady behavior of DU airfoils
New airfoil designs :
03 May, 2004
•
Very thick airfoils for lightweight blades
•
Control of rpm only
=> Low TSR
Low Cl-max, benign stall
=> High TSR
Low drag
•
Aero-elastic tailoring
=> Dynamic airfoil design
(Probably low Cl-max)
31

Design of Airfoils for Wind Turbine Blades

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