1. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. Sweep-Twist Adaptive Blade May 7, 2007 Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. Authors: Tom Ashwill Principle Member of the Technical Staff Wind Energy Technology Department Sandia National Laboratories Gary Kanaby Director of Blade Manufacturing Knight & Carver Presenter Joshua Paquette Member of the Technical Staff Wind Energy Technology Department Sandia National Laboratories

2. 2 Knight & Carver Sweep-Twist Project A project with K&C entitled “Sweep-Twist Adaptive Blade” began in 11/05 Goal – use geometric sweep to couple flap bending with twist to reduce loads in turbulent high winds Why? Increase rotor diameter for enhanced energy capture in low wind sites without increasing loads

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4. 4 Design Window, Tools and Parametric Variations General Parameters Rotor speed (RPM) Blade stiffness (EI) Spanwise mass Chordwise mass Total blade sweep Sweep curve exponent Design Design constrained to operational window of Zond 750 baseline Analytical calculations –FAST, ADAMS, CFD, FEM Parameters for Fine Tuning Planform Airfoil thickness vs. span Sweep magnitude & curve Spar cap position & sizing Airfoil panel composition Materials & process Root forward sweep

5. 5 Section at 55% Span and Root Attachment

6. 6 STAR7d Planform (Sweep-Twist Adaptive Rotor)

7. 7 FEM Model Overview FE model generated in ABAQUS using shell, brick, and hybrid elements # Elements = 87,728 # Nodes = 123,052 Total DOFs = 394,734

8. 8 3-D CFD Modeling

9. 9 Tip Twist Angle ADAMS - GLOBAL = 3.79° at 100% FEM - GLOBAL = 4.16° at 97.6% ADAMS - LOCAL = 3.45° at 100% FEM - LOCAL = 3.83° at 97.6%

10. 10 Load Probability Density 27.1m blade no sweep 24.5m original blade 27.1m with sweep

11. 11 Power Curve Comparison 24.5m original blade EU51 Avg STAR7d Avg Base6 Avg 27.1m blade no sweep 27.1m with sweep

12. 12 STAR7d vs Major Design Targets STAR7dTarget Axis mass moment (kg-m)19,66120,000 Max power deflection 56.6” 56” Flatwise frequency 3.75p > 3p Edgewise frequency 4.57p > 4p Flatwise loads Similar to existing Pitch moment Similar to existing Materials Fiberglass Fiberglass

13. 13 Mold Development

14. 14 Blade Lay-up and Final Fabrication

15. 15 Laboratory Test Setup

16. 16 Static Proof Testing

17. 17 Additional Design Accomplishments 2.2m sweep still allows for 3 blades on trailer Sweep curve eases skin curvature Exotic/expensive materials avoided Uses existing root mold for ~60% of area (inboard region)

18. 18 Summary and Future Activities STAR7d swept blade length is 27.1 m –2.6 m longer than 24.5 m baseline STAR7d is predicted to have same loads but grow energy capture by 5-8% compared to baseline straight blades Static testing of first prototype blade showed good match of natural frequencies & achievement of twist angles on the high side of predictions Fatigue Testing Field Testing on a Zond 750 Machine Future Activities Summary

19. 19 Acknowledgements: Mike Zuteck and Kevin Jackson Thank You for Your Time Presented by Joshua Paquette Sandia’s Wind Energy Department