An examination of wake effects and power production for a group of large wind turbines

Technical Report · Fri Apr 01 04:00:00 EST 1988

DOI:https://doi.org/10.2172/5158081· OSTI ID:5158081

Elliott, D L; Buck, J W; Barnard, J C

Data from a group of three MOD-2 wind turbines and two meteorological towers at Goodnoe Hills were analyzed to evaluate turbine power output and wake effects (losses in power production due to operation of upwind turbines), and atmospheric factors influencing them. The influences of variations in the ambient wind speed, wind direction, and turbulence intensity were the primary factors evaluated. Meteorological and turbine data collected at the Goodnoe Hills site from April 1 to October 17, 1985, were examined to select the data sets for these analyses. Wind data from the two meteorological towers were evaluated to estimate the effect of a wake from an upwind turbine on the wind flow measured at the downwind tower. Maximum velocity deficits were about 25% and 12% at downwind distances of 5.8 and 8.3 rotor diameters (D), respectively. However, the maximum deficits at 5.8 D were about 14/degree/ off the centerline orientation between the turbine and the tower, indicating significant wake curvature. Velocity deficits were found to depend on the ambient wind speed, ranging from 27% at lower speeds (15 to 25 mph) to 20% at higher speeds (30 to 35 mph). Turbulence intensity increases dramatically in the wake by factors of about 2.3 and 1.5 over ambient conditions at 5.8 D and 8.3 D, respectively. An analysis of the ambient (non-wake) power production for all three turbines showed that the MOD-2 power output depends, not only on wind speed, but also on the turbulence intensity. At wind speeds below rated, there was a dramatic difference in turbine power output between low and high turbulence intensities for the same wind speed. One of the turbines had vortex generators on the blades. This turbine produced from 10% to 13% more power than the other two turbines when speeds were from 24 to 31 mph. 11 refs., 21 figs., 2 tabs.

• Research Organization: Pacific Northwest Lab., Richland, WA (USA)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 5158081
• Report Number(s): PNL-6528; ON: DE88009906
• Country of Publication: United States
• Language: English

Related Subjects

17 WIND ENERGY
170604* -- Wind Energy Engineering-- Site Characteristics
DATA
DATA ANALYSIS
ENERGY LOSSES
EXPERIMENTAL DATA
INFORMATION
LOSSES
MACHINERY
NUMERICAL DATA
PERFORMANCE
POWER GENERATION
POWER LOSSES
TURBINES
TURBOMACHINERY
TURBULENCE
WIND TURBINES