Analyzing Aerodynamics of Vertical Axis Wind Turbines with Different Models
Date Issued
2011
Date
2011
Author(s)
Cheng, Yu-Hsuan
Abstract
VAWTs have the advantages of wind direction with no restrictions and convenient operation .VAWTs become the focus of development of offshore turbines in recent years. The aerodynamic characteristics of vertical axis wind turbines are determined by the complex interactions between the flow and the turbine blades. The complication mainly arises from the change of angle of attack, and Reynolds number of the blade airfoil during rotation and this leads to transient periodic aerodynamic forces on the blade. In this study, we analyze the torque and power output of large-scale wind turbines by using both BEM (Blade Element Method) and numerical method. The parameters of calculations include tip-speed ratio(tsr=3,4,5,6), number of blades(2,3,4), and solidity ratio(1/30、1/45、1/60). We found that the maximum power can be obtained at tsr=4, which is dominated by dynamic effect and viscous effect. The turbine with three leaves have the best power efficiency. When solidity is smaller than 1/45, the results of CFD and BEM are similar. Therefore, BEM is appropriate for prediction of large-scale VAWT.
Subjects
Large scale VAWT
BEM
Type
thesis
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