Numerical study to investigate the design parameters of a wind tower to improve the performance of a vertical-axis wind turbine

A wind tower can augment the performance of a vertical-axis wind turbine since it can increase the wind velocity as well as adjust the wind direction. However, it is very important to correctly determine the configuration of the wind tower because the wind tower can also interrupt the wind flow toward the wind turbine. Hence, a numerical analysis was conducted to investigate an effective wind tower configuration using computational fluid dynamics. For practical reasons, a numerical algorithm using a reduced computational domain was applied because the full three-dimensional computational fluid dynamics required huge amounts of computation time for a transient analysis. This method was validated using experimental results and was then applied to the computation of a wind tower with an installed vertical-axis wind turbine. Three wind tower design parameters were chosen for investigation: the inner radius, outer radius, and relative angle of the guide wall. When these parameters were correctly determined, the wind tower always increased the performance of the vertical-axis wind turbine in an omnidirectional wind. In addition, the maximum power coefficient was increased from 0.261 (without the wind tower) to 0.436.