The effect of aerodynamic imbalance on a horizontal axis wind turbine
In order to quantify aerodynamic imbalance effects on the measured loads of a horizontal axis wind turbine, HAWT, an algorithm was developed which is based on work done by de Vries and Manwell. Previous work was expanded to produce a Fortran code, Aero5, that can generate a time series of predicted aerodynamic forces acting on wind turbine blades. The National Renewable Energy Laboratory, NREL, 15 kW combined experiment test turbine was used as the baseline model for all of the tests. The configuration of the machine can be input such that each blade has a different pitch angle or relative azimuthal location and in so doing aerodynamic imbalance effects can be studied. Once the loads on the blades are determined for a specific configuration, the forces can be resolved into any reference frame so that time series data of quantities such as low speed shaft torque, bending moment, generator power, etc. can be predicted and compared to measured field data. During the simulation, input wind conditions were varied such that wind shear and cross wind were included. It was desired to know the effect of small pitch imbalance on machine loads specifically low speed shaft torque, LSST. It was found that a pitch imbalance as small as 2{degree} can result in a once per revolution (1P) oscillation in LSST with an amplitude as large as 60 N-m. It was also found that variations in relative blade azimuthal location had little effect on 1P oscillations in LSST. The results compare favorably to actual wind turbine field data and predictions made in previously papers by Kirchhoff.
- OSTI ID:
- 372135
- Report Number(s):
- CONF-960154--; ISBN 0-9648731-8-4
- Country of Publication:
- United States
- Language:
- English
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