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Title: Investigation of vortex generators for augmentation of wind turbine power performance

Abstract

This study focuses on the use of vortex generators (VGs) for performance augmentation of the stall-regulated AWT-26 wind turbine. The goal was to design a VG array which would increase annual energy production (AEP) by increasing power output at moderate wind speeds, without adversely affecting the loads or stall-regulation performance of the turbine. Wind tunnel experiments were conducted at the University of Washington to evaluate the effect of VGs on the AWT-26 blade, which is lofted from National Renewable Energy Laboratory (NREL) S-series airfoils. Based on wind-tunnel results and analysis, a VG array was designed and then tested on the AWT-26 prototype, designated P1. Performance and loads data were measured for P1, both with and without VGs installed. the turbine performance with VGs met most of the design requirements; power output was increased at moderate wind speeds with a negligible effect on peak power. However, VG drag penalties caused a loss in power output for low wind speeds, such that performance with VGs resulted in a net decrease in AEP for sites having annual average wind speeds up to 8.5 m/s. While the present work did not lead to improved AEP for the AWT-2 turbine, it does provide insight intomore » performance augmentation of wind turbines with VGs. The safe design of a VG array for a stall-regulated turbine has been demonstrated, and several issues involving optimal performance with VGs have been identified and addressed. 15 refs., 34 figs., 10 tabs.« less

Authors:
 [1]
  1. Lynette (R.) and Associates, Seattle, WA (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab., Golden, CO (United States); Lynette (R.) and Associates, Seattle, WA (United States)
Sponsoring Org.:
USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
OSTI Identifier:
414367
Report Number(s):
NREL/SR-440-21399
ON: DE97000087; TRN: AHC29701%%66
DOE Contract Number:
AC36-83CH10093
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Dec 1996
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY; VORTEX AUGMENTED TURBINES; PERFORMANCE TESTING; HORIZONTAL AXIS TURBINES; CAPACITY; AUGMENTATION; EXPERIMENTAL DATA

Citation Formats

Griffin, D.A.. Investigation of vortex generators for augmentation of wind turbine power performance. United States: N. p., 1996. Web. doi:10.2172/414367.
Griffin, D.A.. Investigation of vortex generators for augmentation of wind turbine power performance. United States. doi:10.2172/414367.
Griffin, D.A.. Sun . "Investigation of vortex generators for augmentation of wind turbine power performance". United States. doi:10.2172/414367. https://www.osti.gov/servlets/purl/414367.
@article{osti_414367,
title = {Investigation of vortex generators for augmentation of wind turbine power performance},
author = {Griffin, D.A.},
abstractNote = {This study focuses on the use of vortex generators (VGs) for performance augmentation of the stall-regulated AWT-26 wind turbine. The goal was to design a VG array which would increase annual energy production (AEP) by increasing power output at moderate wind speeds, without adversely affecting the loads or stall-regulation performance of the turbine. Wind tunnel experiments were conducted at the University of Washington to evaluate the effect of VGs on the AWT-26 blade, which is lofted from National Renewable Energy Laboratory (NREL) S-series airfoils. Based on wind-tunnel results and analysis, a VG array was designed and then tested on the AWT-26 prototype, designated P1. Performance and loads data were measured for P1, both with and without VGs installed. the turbine performance with VGs met most of the design requirements; power output was increased at moderate wind speeds with a negligible effect on peak power. However, VG drag penalties caused a loss in power output for low wind speeds, such that performance with VGs resulted in a net decrease in AEP for sites having annual average wind speeds up to 8.5 m/s. While the present work did not lead to improved AEP for the AWT-2 turbine, it does provide insight into performance augmentation of wind turbines with VGs. The safe design of a VG array for a stall-regulated turbine has been demonstrated, and several issues involving optimal performance with VGs have been identified and addressed. 15 refs., 34 figs., 10 tabs.},
doi = {10.2172/414367},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Dec 01 00:00:00 EST 1996},
month = {Sun Dec 01 00:00:00 EST 1996}
}

Technical Report:

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  • Applying vortex generators from 20 to 100 percent span of the Mod-2 rotor resulted in a projected increase in annual energy capture of 20 percent and reduced the wind speed at which rated power is reached by nearly 3 m/sec. Application of vortex generators from 20 to 70 percent span, the fixed portion of the Mod-2 rotor, resulted in a projected increase in annual energy capture of about half this. This improved performance came at the cost of a small increase in cyclic blade loads in below rated power conditions. Cyclic blade loads were found to correlate well with themore » change in wind speed during one rotor revolution.« less
  • Applying vortex generators from 20 to 100 percent span of the Mod-2 rotor resulted in a projected increase in annual energy capture of 20 percent and reduced the wind speed at which rated power is reached by nearly 3 m/sec. Application of vortex generators from 20 to 70 percent span, the fixed portion of the Mod-2 rotor, resulted in a projected increase in annual energy capture of about half this. This improved performance came at the cost of a small increase in cyclic blade loads in below rated power conditions. Cyclic blade loads were found to correlate well with themore » change in wind speed during one rotor revolution.« less
  • Pressure measurements covering a range of wind velocities were made at one span location on the surface of an operating Mod-2, 2500-kW, wind turbine blade. The data, which were taken with and without vortex generators installed on the leading edge, show the existence of higher pressure coefficients than would be expected from two-dimensional wind tunnel data. These high pressure ratios may be the result of three-dimensional flow over the blade, which delays flow separation. Data are presented showing the repetitiveness of abrupt changes in the pressure distribution that occur as the blade rotates. Calculated values of suction and flap coefficientsmore » are also presented.« less
  • This test was conducted as part of the U.S. Department of Energy's (DOE) Independent Testing project. It is a power performance test that the National Renewable Energy Laboratory (NREL) conducted on the Gaia-Wind 11-kW small wind turbine.
  • A technique is presented for estimating the average power output of a wind turbine using, as the wind characteristic input, only the mean annual wind magnitude. Hourly wind speeds are assumed to have a Rayleigh frequency distribution which requires a single parameter input (e.g., the mean value, variance or higher moment values). Based upon a general shape, for the wind speed versus machine output, a generic set of curves is developed to estimate the average power output of wind turbines. Also, estimates of the percent of time the wind turbine would not produce power (percent down time) and the percentmore » of time the wind turbine would be operating at its rated power are presented.« less