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http://dx.doi.org/10.7836/kses.2014.34.3.098

Effect of Blockage Ratio on Wind Tunnel Testing of Small Vertical-Axis Wind Turbines  

Jeong, Houi-Gab (Department of Civil Engineering, Chonbuk National University)
Lee, Seung-Ho (KOCED Wind Tunnnel Center, Chonbuk National University)
Kwon, Soon-Duck (Department of Civil Engineering, Chonbuk National University)
Publication Information
Journal of the Korean Solar Energy Society / v.34, no.3, 2014 , pp. 98-106 More about this Journal
Abstract
The effect of blockage ratio on wind tunnel testing of small vertical-axis wind turbine has been investigated in this study. Height and rotor diameter of the three blades Darrieus vertical axis wind turbine used in present test were 0.4m and 0.35m respectively. We measured the wind speeds and power coefficient at three different wind tunnels where blockage ratio were 3.5%, 13.4% and 24.7% respectively. The test results show that the measured powers have been strongly influenced by blockage ratio, generally increased as the blockage ratio increases. The maximum power at higher blockage ratio has been obtained at relatively high tip speed ratio compared with that at low blockage ratio. The measured power coefficients under high blockage ratio can be improved from proper correction using the simple correction equation based on blockage factor. In present study, the correction error for power coefficient can be less than 5%, however correction effectiveness reveals relatively poor at high blockage ratio and low wind speed.
Keywords
Vertical-axis wind turbine; Blockage ratio; Wind tunnel test; Blockage effect; Blockage factor; Power coefficient;
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