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Advanced biplane blade design for large-scale wind turbines
UCLA Tech Forum
February 6, 2014 Funding provided by: UCLA Graduate Division • California Energy Commission
Link Foundation • Communities Foundation of Texas • Clean Green IGERT
Perry Roth-Johnson Ph.D. Candidate
Energy Innovation Lab | www.wirz.seas.ucla.edu
UCLA, Mechanical & Aerospace Engineering
Advisor: Prof. Richard Wirz
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2 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Roadmap
Image: Leon Salcedo | flic.kr/p/bLJ5hH
1. Background & motivation for large wind turbine blades
2. Biplane blade concept
a. Aerodynamic studies
b. Structural studies
3. Path forward
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3 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Wind turbines are expected to grow
UpWind (2011), “Design limits and solutions for very large wind turbines - A 20 MW turbine is feasible”.
𝑃rotor = 12𝐶𝑝𝜌𝜋𝑅2𝑉3
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4 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Challenges for large wind turbine blades
Sandia National Lab | moourl.com/2tbt5
standard compromise:
structures > aerodynamics
Is it feasible to further upscale conventional blades, or is a new design needed?
Blade loads Blade mass
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5 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Roadmap
Image: Leon Salcedo | flic.kr/p/bLJ5hH
1. Background & motivation for large wind turbine blades
2. Biplane blade concept
a. Aerodynamic studies
b. Structural studies
3. Path forward
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6 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
“Biplane blade” design concept
Wirz (2011), “Advanced Aerodynamic and Structural Blade and Wing Design,” USPTO Int’l App. No. PCT/US11/26367.
Images: Phillip Chiu
biplane
inboard region
monoplane
outboard region
mid-blade
joint
root
joint
Is the biplane blade a feasible design to address the challenges of large blades?
biplane monoplane
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7 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Roadmap
Image: Leon Salcedo | flic.kr/p/bLJ5hH
1. Background & motivation for large wind turbine blades
2. Biplane blade concept
a. Aerodynamic studies
b. Structural studies
3. Path forward
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8 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Thick monoplane vs. biplane
Method: 2D, steady-state,
incompressible viscous CFD
(FLUENT commercial CFD code)
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9 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Aerodynamic results
Roth-Johnson & Wirz (2012), “Aero-structural investigation of biplane wind turbine blades,” Wind Energy.
biplane monoplane
The biplane is more aerodynamically
efficient than the thick monoplane.
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10 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Parametric analysis of biplane airfoils
Wind turbine-specific airfoil:
DU 91-W2-250
Aerodynamic performance with
varying gap, g, and stagger, s
What is the aerodynamically optimal
biplane configuration?
Chiu & Wirz (in preparation), “Aerodynamic performance of biplane airfoils for wind turbine blades”.
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11 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Parametric analysis: 2D CFD
[1] Chiu & Wirz (in preparation), “Aerodynamic performance of biplane airfoils for wind turbine blades”.
[2] Drela & Giles (1986), “Viscous-inviscid analysis of transonic and low Reynolds number airfoils. AIAA Journal.
Method: 2D coupled
viscous/inviscid
incompressible CFD
(MSES research code2)
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12 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Parametric analysis: wind tunnel testing
Chiu & Wirz (in preparation), “Aerodynamic performance of biplane airfoils for wind turbine blades”.
Caltech Lucas Wind Tunnel
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13 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Roadmap
Image: Leon Salcedo | flic.kr/p/bLJ5hH
1. Background & motivation for large wind turbine blades
2. Biplane blade concept
a. Aerodynamic studies
b. Structural studies
3. Path forward
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14 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
How to design the biplane inboard region?
joint length, 𝑟𝑗 =?
gap, 𝑔 =?
[1] Lowe & Satterly (1996), “Comparison of Coupon and Spar Tests,” Design of composite structures against fatigue: applications to wind turbine blades.
The spar is the primary load-bearing component in the blade.1
Glass
Fiber
Reinforced
Plastic
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15 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
How to design the biplane inboard region?
“Structures-first” approach
for biplane blade
1. Design internal spar
structure
2. Fit airfoil exterior over
spar
2
2
1
1
joint length, 𝑟𝑗 =?
gap, 𝑔 =?
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16 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Want to use a parametric analysis
composite materials tapered spar thickness
joint length, 𝑟𝑗 =?
gap, 𝑔 =?
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17 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Parametric analysis needs fast & accurate tools
[1] Bauchau (1998), Multibody System Dynamics. [2] Hodges & Yu (2007), Wind Energy.
[3] Chen, Yu, & Capellaro (2009), Wind Energy. [4] Otero & Ponta (2010), J. Solar Energy Eng. [5] Roth-Johnson & Wirz (2012), Wind Energy.
Technical University of Denmark |
risoecampus.dtu.dk/Vindenergi/VEA/VIM/Becas.aspx
Alternate approach
1D FEA (DYMORE1) and
2D cross-sectional analysis (VABS2,3)
• Fast computation, with good accuracy2,3
• Modeled conventional blades4
• Validated approach for biplane blades5
Windpower Engineering | windpowerengineering.com
Direct approach
3D finite element analysis (FEA)
• High accuracy
• Time consuming
• Model setup
• Computational time
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18 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Sandia completely defined the blade structure
Images: Edward Lin
Griffith & Ashwill (2011), “The Sandia 100-meter All-glass Baseline Wind Turbine Blade: SNL 100-00”.
composite materials tapered spar thickness
100 m
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19 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Spars were designed from the Sandia blade
Sandia blade
monoplane spar
biplane spar
spar geometry, composite layup, materials
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20 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Equivalent static loads
biplane spar
monoplane spar
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21 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Computational model: results
upper inboard element
lower inboard element
Roth-Johnson & Wirz (in review), “Structural design of spars for 100-meter biplane wind turbine blades,” Renewable Energy.
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22 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
incre
asin
g
join
t le
ngth
-to
-sp
an r
atio
, 𝑟 𝑗
/𝑅
increasing gap-to-chord ratio, 𝑔/𝑐
Parametric analysis: results
1 2 3
4 5 6
7 8 9
10 11 12
13 14 15
1 2 3
4 5 6
7 8 9
10 11 12 13 14 15
(lighter colors are better)
Biplane
should
extend to
~50% span
Roth-Johnson & Wirz (in review), “Structural design of spars for 100-meter biplane wind turbine blades,” Renewable Energy.
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23 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Conclusions
The biplane blade is a feasible design for large wind turbine blades.
Showed aero-structural benefit of biplane blade
Structural studies
Searched a large parameter
space in a short amount of time
Found a near-optimum
structural configuration
Aerodynamic studies
Biplanes have improved performance
compared to thick inboard airfoils
Larger gap and stagger tends to
improve performance of biplanes
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24 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Roadmap
Image: Leon Salcedo | flic.kr/p/bLJ5hH
1. Background & motivation for large wind turbine blades
2. Biplane blade concept
a. Aerodynamic studies
b. Structural studies
3. Path forward
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25 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Path forward
• Aerodynamic shape optimization
• Full blade analysis
– Structural analysis of staggered biplane region
– 3D FEA: dynamics and buckling
– Torsion/edgewise response
– 3D CFD
– Aeroelastic/fatigue simulations
• Manufacturing & costs
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26 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Intellectual property in wind energy
1. Wirz R.E., “Advanced Aerodynamic and Structural Blade and Wing Design,”
PCT Application No. PCTIUS2011/026367, U.S. Patent Application 13/581,278,
filed Aug 24, 2012.
2. Wirz R.E., Aspe S., “Design for High Performance Wind Turbines,” U.S.
Patent Application 13/581,286, filed Aug 24, 2012.
3. Roth-Johnson P., Wirz R.E., “High-Strength Wind Turbine Blades and Wings,”
U.S. Patent Application 61/654708, filed Jul 01, 2013.
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27 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Small wind
Max power
Solar: 245 W
Wind: 500 W
solar
wind
3 6 9 12
average annual wind speed [m/s]
1500
800
100
an
nu
al
en
erg
y
ou
tpu
t [k
Wh
/yr]
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28 Roth-Johnson & Wirz, Advanced biplane blade design for large-scale wind turbines
Acknowledgements
Prof. Richard Wirz Phillip Chiu Edward Lin