Sandia National Laboratories has been conducting research on 100-meter wind turbine blades since 2009 to reduce technology risk and identify challenges of scaling up blade size. Their research has included developing detailed reference designs of 100-meter blades, studying advanced materials like carbon fiber and core materials, and investigating the effects of blade geometry and slenderness. Their work has resulted in four designs - SNL100-00 through SNL100-03 - each incorporating design improvements. All reference models, reports, and other materials from the project are publicly available online to support continued research on large wind turbine blades.

1. An Update on the Sandia 100-meter Blade Project:
Large Blade Public Domain Reference Models and Cost Models
D. Todd Griffith (dgriffi@sandia.gov)
Sandia National Laboratories
Sandia Wind Turbine Blade Workshop (8/27/2014)
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin
Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2014-1418P

2. Timeline for 100-meter blade studies
 2009: Project start, scaling studies, parameters for the
baseline 100-meter blade
 2011: Completed and published the SNL100-00 All-glass
Baseline Blade
 2011-2012: Carbon design studies: SNL100-01 Blade
 2012-2013: Advanced core studies: SNL100-02 Blade
 2013-2014: Flatback airfoils/slenderness studies: SNL100-03
Blade
Blade design studies required a turbine model for aero-elastic
loads analysis: we up-scaled the NREL 5MW turbine model and
also released that model as a 13.2 MW reference with the blade
files
2

3. Large Offshore Rotor Development (100-meter Blade
Project)
 Summary
• Reduce technology risk
• Public domain blade project
 Objectives/Focus Areas
• Identify trends and challenges
• Detailed 100-meter reference designs
• Targeted follow-on studies: advanced
concepts, materials, flutter,
manufacturing cost trends, thick
airfoils, CFD
 Products
• Design reports
• 100-m blade and 13.2 MW turbine
reference models
http://largeoffshorerotor.sandia.gov
Partners:
• None funded, In-kind
• 50+ users

4. Detailed Design: Loads and Safety
Factors
Acceptance of the design to blade design standards is a key
element of the work; certification process using IEC and GL
specifications; Class IB siting [2]
Wind Condition Description
IEC DLC
Number
Design Situation
(Normal or Abnormal)
ETM (Vin < Vhub < Vout) Extreme Turbulence Model 1.3 Power Production (N)
ECD (Vhub = Vr +/- 2 m/s)
Extreme Coherent Gust with
Direction Change
1.4 Power Production (N)
EWS (Vin < Vhub < Vout) Extreme Wind Shear 1.5 Power Production (N)
EOG (Vhub = Vr +/- 2 m/s) Extreme Operating Gust 3.2 Start up (N)
EDC (Vhub = Vr +/- 2 m/s)
Extreme Wind
Direction Change
3.3 Start up (N)
EWM (50-year occurrence)
Extreme Wind
Speed Model
6.2 Parked (A)
EWM (1-year occurrence)
Extreme Wind
Speed Model
6.3 Parked (N)
Safety factors for materials and loads included for buckling,
strength, deflection, and fatigue analyses

5. Baseline Materials Data: Sources
 Montana State Test Data for glass materials and carbon
 For SNL100-00: UPWIND program materials (foam,
resin, gelcoat)
 For SNL100-02 and -03: Balsa and PET foam core
5

6. SNL100-00: All-glass Design Review
Fatigue
Maximum
Strain
Tip deflection
Flutter
Buckling

1290 year fatigue life

48.2% margin

1.77m clearance
1.2-1.3x max speed

6.3% margin
Design Performance
Review

7. SN100-00: Layup
[2]
(a) 0.0 meters (root circle) (b) 2.4 meters (shear webs begin) (c) 8.9 meters(transition)
(d) 14.6 meters (third web begins) (e) 19.5 meters (max chord) (f) 35.8 meters

8. SNL100-00 External Geometry
 The inboard airfoils of maximum chord were produced by interpolation.
 Otherwise, this baseline SNL100-00 designed uses a scaled-up chord distribution and
outboard airfoil shapes from DOWEC; same twist as well
[2]
6
5
4
3
2
1
0
-1
-2
-3
-4
0.0 0.2 0.4 0.6 0.8 1.0
(meters)
Blade Span Fraction
Leading Edge
Trailing Edge

9. 3-Blade Upwind Rotor
Parameter Value
Blade Designation SNL100-00
Wind Speed Class IB
Blade Length (m) 100
Blade Weight (kg) 114,172
Span-wise CG location (m) 33.6
# shear webs 3
Maximum chord (m) 7.628 (19.5% span)
Lowest fixed root natural
frequency (Hz)
0.42
Control
Variable speed,
collective pitch
Notes
6% (weight) parasitic
resin, all-glass materials
Material Description Mass (kg)
Percent
Blade Mass
E-LT-5500
Uni-axial
Fiberglass
37,647 32.5%
Saertex
Double Bias
Fiberglass
10,045 8.7%
EP-3 Resin 51,718 44.7%
Foam Foam 15,333 13.3%
Gelcoat Coating 920 0.8%
Max operating speed: 7.44 RPM
Cut in/out wind speed: 3.0/25.0 m/s
Design Scorecards for all Designs

10. Industry survey of blade mass: Commercial blades (20-60
meters), recent large prototype blades (73-83 meters), and
research concept blades (61.5, 86, 100, 123 meters)
SNL100-XX
Series
SNL100-XX series
shows a pathway to
high innovation weight
SNL100-00:
Glass
Baseline
SNL100-01:
Carbon spar
SNL100-02:
Core
SNL100-03:
Geometry

11. SNL100 Follow-on Projects
These are the follow-on study
areas addressed by Sandia; many
additional issues addressed by
users of the 100-meter blade
1. Sandia Flutter Study
reference models.
2. Altair/Sandia CFD Study
3. Sandia Blade Manufacturing Cost Model
4. 100m Carbon Design Studies: SNL100-01
5. 100m Core Material Studies: SNL100-02
6. 100m Aero-structural Studies: SNL100-03

12. 1. Flutter parameters study and
improvements to flutter tool
12
Data shown are from classical
flutter analyses:
 SNL CX-100; 9-meter
experimental blade
 WindPact 33.25-meter 1.5MW
concept blade
 SNL 61.5-meter blade
(preliminary design)
 SNL100-00 Baseline Blade
1. Resor, Owens, and Griffith. “Aeroelastic Instability of Very Large Wind Turbine Blades.” Scientific
Poster Paper; EWEA Annual Event, Copenhagen, Denmark, April 2012.
2. Owens, B.C., Griffith, D.T., Resor, B.R., and Hurtado, J.E., “Impact of Modeling Approach on Flutter
Predictions for Very Large Wind Turbine Blade Designs,” Proceedings of the American Helicopter
Society (AHS) 69th Annual Forum, May 21-23, 2013, Phoenix, AZ, USA, Paper No. 386.
Design impacts identified &
SNL Flutter Tool Improved

13. 3. Sandia Blade Manufacturing Cost Model
(version 1.0)
Important Study of Labor
Operations Trends with Scale
13
• Components of the Model:
– Materials, Labor, Capital Equipment
– Detailed Labor Breakdown by major operation
– Reports: SAND2013-2733 & SAND2013-2734
One example: An analysis of labor costs shows the growth in labor hours for area-driven
manufacturing tasks such as paint prep and paint as blades grow longer.

14. 4. Carbon spar (SNL100-01)
14
Cross-sections at 14.6m station
SNL100-00: Glass Spar SNL100-01: Carbon Spar
• Spar width reduced by
50%
• Shear web thickness
reduced by 25%
• 35% weight reduction
Carbon blade weight and cost
baseline established (using
SNL Blade Cost Model)

15. 5. Advanced core material (SNL100-02)
Performance Focus:
• Balsa in critical buckling areas
• PET foam (recyclable) in non-critical buckling areas and shear webs
• ~20% additional weight reduction
Secondary Benefit:
• Eco-friendly core materials approach (regrowable and recyclable)
Primary and secondary weight reduction benefits;
Recyclable foam has good potential for large blade applications

16. 6. Flatback airfoils/Slenderness Study
(SNL100-03)
Focused on effect and limits of blade slenderness
Opportunity to reverse many trends, including:
• Weight growth – innovative weight projection anticipated
• Buckling
• Flutter, Deflection, Fatigue
• Surface Area Driven Labor Operations
Increasing
Slenderness
Increased blade slenderness
has advantages and
disadvantages – these design
studies aid in better
understanding the trade-offs

17. Preliminary Design work for SNL100-03 presented in:
Griffith, D.T., Richards, P.W., “INVESTIGATING THE EFFECTS OF FLATBACK AIRFOILS
AND BLADE SLENDERNESS ON THE DESIGN OF LARGE WIND TURBINE BLADES,”
Proceedings of 2014 European Wind Energy Association (EWEA) Annual Event,
Barcelona, Spain, March 2014, Paper # 225.
17
SNL100-
02
SNL100-03:
Rev0
SNL100-03:
Rev1
SNL100-03:
Rev2
Geometry Description Baseline DU-Optimized More slender Less Slender
Airfoil Family DU DU Flatbacks Flatbacks
Mass (kg) 59,047 53,146 50,530 53,671
Flap RBM (max) (kN-m) 111,900 87,410 74,930 92,600
Tip Deflection (m) 10.51 10.62 13.37 11.02
Spar Fatigue @ 15% (years) 646 4004 340 2641
Trailing Edge Fatigue @ 15%
(years)
352 31.6 0.3 2.7
Lowest Panel Buckling Freq. 2.10 -- 3.60 3.15
Flutter Speed Ratio 1.65 1.67 1.54 1.62
Surface Area (sq. meters) 1262 1021 886 979

18. Resources, Model Files, Next Steps
[2]
Model files on Project Website (both blade and turbine)
• http://largeoffshorerotor.sandia.gov
What’s Available:
1. Detailed Blade Models (Layups + Geometry)
• SNL100-00, SNL100-01, SNL100-02, SNL100-03
• 61.5 meter (5 MW)
2. SNL13.2-00-Land Turbine Model (in FAST)
3. Sandia Blade Manufacturing Cost Model – version 1.0
4. Design Reports
Next Steps? Sandia is looking to contribute both existing and to
future Blade & Turbine Reference Models and Cost Models
D. Todd Griffith dgriffi@sandia.gov
This work was funded by the US DOE Wind and Water Power
Technology Office.