Observations of wind turbine wakes and surface roughness effects on wind flow variability
- Pacific Northwest Lab., Richland, WA (USA)
Wind data collected at nine meteorological towers at the Goodnoe Hills MOD-2 wind turbine site were analyzed to characterize the wind flow over the site both in the absence and presence of wind turbine wakes. Free-flow characteristics examined were the variability of wind speed and turbulence intensity across the site as a function of wind direction and surface roughness. The nine towers' data revealed that scattered areas of trees upwind of the site caused pronounced variations in the wind flow over the site. Wind turbine wake characteristics analyzed included the average velocity deficits, wake turbulence, wake width, wake trajectory, vertical profile of the wake, and the stratification of wake properties as a function of the ambient wind speed and turbulence intensity. The wind turbine rotor disk spanned a height of 15 m to 107 m. The nine towers' data permitted a detailed analysis of the wake behavior at a height of 32 m at various downwind distances from 2 to 10 rotor diameters (D). The relationship between velocity deficit and downwind distance was surprisingly linear, with average maximum deficits ranging from 34% at 2 D to 7% at 10 D. Largest deficits were at low wind speeds and low turbulence intensities. Average wake widths were 2.8 D at a downwind distance of 10 D. Implications for turbine spacing are that, for a wind farm with a 10-D row separation, array losses would be significantly greater for a 2-D than a 3-D spacing because of incremental effects caused by overlapping wakes. Other interesting wake properties observed were the wake turbulence, the vertical variation of deficits, and the trajectory of the wake.
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6342731
- Journal Information:
- Solar Energy (Journal of Solar Energy Science and Engineering); (USA), Vol. 45:5; ISSN 0038-092X
- Country of Publication:
- United States
- Language:
- English
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WASHINGTON
WIND
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WIND TURBINES
ENVIRONMENTAL EFFECTS
AIR FLOW
COMPLEX TERRAIN
DATA ACQUISITION
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FLOW RATE
LOSSES
METEOROLOGY
ROTORS
SPACE DEPENDENCE
STRATIFICATION
TOPOGRAPHY
TREES
TURBULENCE
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FLUID FLOW
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TURBINES
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170500* - Wind Energy- Environmental Aspects
170604 - Wind Energy Engineering- Site Characteristics