Environmental Engineering Reference
In-Depth Information
Summary Comments on Wind Turbine Wake Effects
As the demand for wind turbine installations increases and the availability of large sites
with high energy flow decreases, it will be necessary to employ arrays of higher density in
the good wind areas as well as to install arrays on sites with lower wind speeds. In both
cases, an understanding of array effects is critical to maximizing energy production. Since
1976 there has been an extensive research effort devoted to predicting wake interference
effects. For uniform flows corresponding to flat terrain, the numerical modeling has
reached an adequate state, particularly with semi-empirical models in which constants may
be adjusted to conform with the accumulating data base.
For non-uniform flows, however, the situation is still relatively unquantified. Reliable
wake-effect data are still needed from commercial wind power stations located in complex
terrain. It is noted that modeling the array interference in this case must be based on an
adequate modeling of the wind flow itself over complex terrain, and this topic is generally
considered to be incompletely understood. One must have an acceptable wind flow model
without wind turbines before one can reliably superimpose the turbine array effects. Simple
approximate models for wake interference are probably as accurate as the complex-terrain
flow models now available. Refinements are required for both, in order to produce an
acceptable operational model for the micrositing of wind turbines.
References
Ainslie, J. F., 1985, “Development of an Eddy-Viscosity Model for Wind Turbine Wakes,”
Proceedings, 7th BWEA Conference , British Wind Energy Association, London:
Multi-Science Publishing Co.
Buhl, M. L., Jr., A. D. Wright, and J. L. Tangler, 1998, Wind Turbine Design Codes : A
Preliminary Comparison of the Aerodynamics , NREL/CP 23975, Golden, Colorado:
National Renewable Energy Laboratory.
Craaford, J., 1975, (personal communication).
Crespo A., F. Manuel, D. Moreno, E. Fraga, and J. Hernandez, 1985, “Numerical Analysis
of Wind Turbine Wakes,” Proceedings, Workshop on Wind Energy Application ,
Delphi, Greece.
Eppler, R., and K. M. Somers, 1980, A Computer Program for the Design and Analysis of
Low-Speed Aitfoils , NASA TM-80210, Hampton, Virginia: NASA Langley Research
Center.
Faxen, T., 1978, “Wake Interaction in an Array of Windmills,” Proceedings, 2nd
International Symposium on Wind Energy Systems , Amsterdam.
Gyatt, G. W., and P. B. S. Lissaman, 1985, Development and Testing of Tip Devices for
Horizontal Axis Wind Turbines , NASA CR 174991, Cleveland, Ohio: NASA Lewis
Research Center.
Hibbs, B. D., 1986, HAWT Performance with Dynamic Stall , SERI/STR-217-2732, Golden,
Colorado: National Renewable Energy Laboratory.
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