Offshore Wind: Sandia Large Rotor Development

Overview

Sandia National Laboratories Wind Energy Technologies Department, creates and evaluates innovative large blade concepts for horizontal axis wind turbines to promote designs that are more efficient aerodynamically, structurally, and economically. Recent work has focused on the development of a 100-meter blade for a 13.2 MW horizontal axis wind turbine, a blade which is significantly longer than the largest commercial blades of today (approximately 60 meters long).

The initial study focused on development, documentation, and dissemination of the Sandia 100-m All-glass Baseline Wind Turbine Blade, termed “SNL100-00”, which employs conventional architecture and fiberglass-only composite materials. A detailed composite layup and geometry are available through the links below, along with the associated 13.2MW Turbine Design Models.

Analyses of the baseline model for design loads from international standards demonstrated acceptance of the design with respect to strength, fatigue, deflection, and buckling. Challenges and opportunities for large blade research are summarized below.

In future work, these 100-meter blade models will provide a starting point for consideration of blade innovations with potential performance improvement, weight reduction, and cost improvements. A design scorecard is provided below for use by researchers to compare the effect of innovations on the principal design drivers which include weight, fatigue life, buckling, tip deflection, maximum strains, and aeroelastic stability (flutter margin). The 13.2 MW turbine models also provide a starting point for turbine and turbine control studies.

Challenges and Opportunities

Initial Observations
A 100-m blade using conventional geometry and all-glass materials is possible. All design requirements are satisfied including maximum strains, tip-tower clearance, buckling resistance,
and fatigue life. However, the blade weight for the initial design is very high (and not cost-effective) and the flutter margin is small. Future work can address these concerns while improving performance and reducing cost.

Future Work and Potential Research Opportunities
Significant opportunity exists to reduce weight and cost through innovations and structural optimization. Innovations such as the use of carbon fiber, very thick airfoils such as flatback airfoils, bend-twist coupling, geometric sweep, pre-bending, and unique architecture, anti-buckling devices, structured core, and active control could be considered. Many of these innovations have been demonstrated in prior Sandia blade development programs, which are documented in Sandia Wind Energy publications.

Other considerations for future work and potential research in large rotor technology are outlined in the SNL100-00 design report provided below.

Sandia Blade and Turbine Design Models: Reports and Model Files

Model Request Form (191KB .doc)
Design Scorecard (182KB .doc)

Blade Models: Detailed Design Information

(Blade Key: SNL[length(m)]-[version])
Blade Designation	Blade Report	Brief Description	Design Scorecard	Model Files Mini-report
“SNL100-00″	SAND2011-3779(1.22MB PDF)	Sandia 100m All-glass Baseline Blade	SNL 100-00 Design Scorecard (327KB PDF)	SNL100-00 Model Files Description Report (447KB PDF)
“SNL100-01″	—–	SNL100-00 with design modification series #1	—–	Future Release
“SNL100-02″	—–	SNL100-00 with design modification series #2	—–	Future Release

Turbine Models

	(Turbine Key: SNL[rating(MW)]-[blade version]-[siting/foundation type])
	Turbine Designation	Brief Description	Model Files Mini-report
	SNL13.2-00-Land	13.2 MW land-based turbine model with SNL100-00 Blades	SNL13.2-00-Land Model Files Description Report (321KB PDF)
	SNL13.2-01-Land	—–	—–
	SNL13.2-02-Land	—–	—–

References

Griffith, D.T. and Ashwill, T.D., “The Sandia 100-meter All-glass Baseline Wind Turbine Blade: SNL100-00,” Sandia National Laboratories Technical Report, SAND2011-3779, June 2011 (1.22MB PDF).

“Sandia Large Rotor Design Scorecard,” Sandia National Laboratories Technical Report, SAND2011-9113P, December 2011 (182KB PDF).