Design improvements to the ESI-80 wind turbine
- Univ. of Massachusetts, Amherst, MA (United States)
This paper describes two investigations related to improvements to an ESI-80 wind turbine. One of them involved modeling the tip flaps during braking. The other was a study of the turbine behavior with various delta-3 angles. These topics are of interest since the turbine is a two-bladed, teetered, free-yaw machine with tip flaps and an adjustable delta-3 angle. Tip flaps are used for slowing the turbine during shutdown and as an emergency system to insure that the rotor does not go into an overspeed condition in the event of failure of other parts of the system. Upon deployment, the tip flaps are exposed to a number of varying forces including aerodynamic, damper, spring, centripetal, and gravitational forces and forces at the hinged connection to the blades. For maximum braking the angle of tip flap deployment needs to be as large as possible without striking the blades in overspeed conditions and when covered with ice. To investigate tip flap design tradeoffs, a dynamic model of the tip flaps on the modified ESI-80 turbine was developed. Results include a determination of the effect of the addition of weight to the flap, overspeed conditions, and changes in damping coefficient. Changes in the delta-3 angle can be used to couple pitching and flapping motions, affecting both teeter and yaw behavior. These effects have been investigated using a modified version of YawDyn. The effects of changes in the delta-3 angle on the teeter and yaw behavior of the modified ESI-80 wind turbine were investigated. Results show that increased teeter excursions in steady high winds can be reduced by increasing the delta-3 angle. Increasing the delta-3 angle may also increase yaw motion in low wind speeds. Results suggest that the optimum delta-3 angle for improved performance may be substantially greater than the presently used angle of zero degrees. 8 refs., 16 figs.
- Research Organization:
- US Department of Energy (USDOE), Washington DC (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
- OSTI ID:
- 447488
- Report Number(s):
- CONF-960630-; ON: DE97002833; TRN: 97:001056-0053
- Resource Relation:
- Conference: Windpower `96: American Wind Energy Association (AWEA) conference, Denver, CO (United States), 23-27 Jun 1996; Other Information: PBD: [1996]; Related Information: Is Part Of Windpower `96 - Proceedings of the American Wind Energy Association; PB: 682 p.
- Country of Publication:
- United States
- Language:
- English
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