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

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)

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Timeline for 100-meter blade studies

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

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

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.govPartners:

• None funded, In-kind• 50+ users

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 DescriptionIEC 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 Change1.4 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 Change3.3 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

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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

Fatigue

Maximum Strain

Tip deflectionBuckling

Flutter

1290 year fatigue life

48.2% margin

1.77m clearance

1.2-1.3x max speed

6.3% margin

Design PerformanceReview

SNL100-00: All-glass Design Review

SN100-00: Layup

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(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

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

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0.0 0.2 0.4 0.6 0.8 1.0

-4

-3

-2

-1

0

1

2

3

4

5

6 Leading Edge

Trailing Edge

Blade Span Fraction

(met

ers)

3-Blade Upwind Rotor

Parameter ValueBlade 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

ControlVariable speed, collective pitch

Notes6% (weight) parasitic

resin, all-glass materials

Material Description Mass (kg)Percent

Blade Mass

E-LT-5500Uni-axial

Fiberglass37,647 32.5%

SaertexDouble 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 RPMCut in/out wind speed: 3.0/25.0 m/s

Design Scorecards for all Designs

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-XXSeries

SNL100-XX series shows a pathway to high innovation weight

SNL100-00: Glass

Baseline

SNL100-01:Carbon spar

SNL100-02:

Core SNL100-03: Geometry

SNL100 Follow-on Projects

1. Sandia Flutter Study2. Altair/Sandia CFD Study3. Sandia Blade Manufacturing Cost Model4. 100m Carbon Design Studies: SNL100-015. 100m Core Material Studies: SNL100-026. 100m Aero-structural Studies: SNL100-03

These are the follow-on study areas addressed by Sandia; many

additional issues addressed by users of the 100-meter blade

reference models.

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1. Flutter parameters study and improvements to flutter tool

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.

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

Design impacts identified &SNL Flutter Tool Improved

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3. Sandia Blade Manufacturing Cost Model (version 1.0)

• 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.

Important Study of Labor Operations Trends with Scale

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4. Carbon spar (SNL100-01)

SNL100-00: Glass Spar SNL100-01: Carbon Spar

Cross-sections at 14.6m station

• 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)

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

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

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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.

SNL100-02

SNL100-03: Rev0

SNL100-03: Rev1

SNL100-03: Rev2

Geometry Description Baseline DU-Optimized More slender Less SlenderAirfoil Family DU DU Flatbacks Flatbacks

Mass (kg) 59,047 53,146 50,530 53,671Flap RBM (max) (kN-m) 111,900 87,410 74,930 92,600

Tip Deflection (m) 10.51 10.62 13.37 11.02Spar Fatigue @ 15% (years) 646 4004 340 2641Trailing Edge Fatigue @ 15%

(years)352 31.6 0.3 2.7

Lowest Panel Buckling Freq. 2.10 -- 3.60 3.15Flutter Speed Ratio 1.65 1.67 1.54 1.62

Surface Area (sq. meters) 1262 1021 886 979

Resources, Model Files, Next Steps

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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.