NREL airfoil families for HAWTs
- National Renewable Energy Lab., Golden, CO (United States)
- Airfoils Incorporated, State College, PA (United States)
The development of special-purpose airfoils for horizontal-axis wind turbines (HAWTs) began in 1984 as a joint effort between the National Renewable Energy Laboratory (NREL), formerly the Solar Energy Research Institute (SERI), and Airfoils, Incorporated. Since that time nine airfoil families have been designed for various size rotors using the Eppler Airfoil Design and Analysis Code. A general performance requirement of the new airfoil families is that they exhibit a maximum lift coefficient (c{sub 1,max}) which is relatively insensitive to roughness effects. The airfoil families address the needs of stall-regulated, variable-pitch, and variable-rpm wind turbines. For stall-regulated rotors, better peak-power control is achieved through the design of tip airfoils that restrain the maximum lift coefficient. Restrained maximum lift coefficient allows the use of more swept disc area for a given generator size. Also, for stall-regulated rotors, tip airfoils with high thickness are used to accommodate overspeed control devices. For variable-pitch and variable-rpm rotors, tip airfoils having a high maximum lift coefficient lend themselves to lightweight blades with low solidity. Tip airfoils having low thickness result in less drag for blades having full-span pitch control. Annual energy improvements from the NREL airfoil families are projected to be 23% to 35% for stall-regulated turbines, 8% to 20% for variable-pitch turbines, and 8% to 10% for variable-rpm turbines. The improvement for stall-regulated turbines has been verified in field tests.
- Research Organization:
- American Wind Energy Association, Washington, DC (United States)
- OSTI ID:
- 269354
- Report Number(s):
- CONF-950309-; ON: DE96011159; TRN: 96:003988-0017
- Resource Relation:
- Conference: 25. annual conference and exhibition on wind power, Washington, DC (United States), 26-30 Mar 1995; Other Information: PBD: 1995; Related Information: Is Part Of Windpower `95 - Proceedings of the American Wind Energy Association; PB: 624 p.
- Country of Publication:
- United States
- Language:
- English
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