Abstract
This report describes how numerical lifting-surface theory is applied to the calculation of a horizontal-axis wind turbine's aerodynamic characteristics and performance. The report also describes how such an application is implemented as a computer program. The method evolved from rotary-wing and helicopter applications and features a detailed, prescribed wake. The wake model extends from ahovering-rotor experimental generalization to include the effect of the windmill brake state on the radial and axial displacement rates of the trailing vortex system. Performance calculations are made by coupling the lifting-surface circulation solution to a blade-element analysis that incorporates two-dimensional airfoil characteristics as functions of angle of attack and Reynolds number.Several analytical stall models are also provided to extend the airfoil characteristics beyond the limits of available data. Although this work focuses on the steady-performance problem, the method includes ways to investigate the effects of wind-shear profile, tower shadow, and off-axis shaft alignment. Correlating the method to measured wind-turbine performance, and comparing it toblade-element momentum theory calculations, validate and highlight the extreme sensitivity of predictions to the quality of early poststall airfoil behavior.
Original language | American English |
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Number of pages | 312 |
State | Published - 1987 |
Bibliographical note
Work performed by Computational Methodology Associates, Hurst, TexasNREL Publication Number
- NREL/STR-217-3163
Keywords
- aerodynamic characteristics
- numerical theory
- performance analysis
- simulation
- wind energy
- wind turbine