Experiments on fairing designs for a wind turbine tower

An experiment was conducted to analyze the ability of the fairing to prevent flow separation and minimize the velocity deficit in the tower wake. Flow visualization and particle image velocimetry (PIV) were used to analyze flow separation and wake effects of two symmetrical airfoils at 0 and 10 deg. The flow visualization results showed that both the C30u and E863 airfoils had similar performances with respect to flow separation. At 0 deg, the flow remained attached, but at 10 deg, the flow separated for both airfoils. The Reynolds number for the experiments was two orders of magnitude less than the full-scale Reynolds number, so the flow was more likely to remain attached for the full-scale fairing because turbulent boundary layers are more resistant to flow-separation. If the flow does remain attached at higher angles of attack at the full-scale Reynolds number, the tower fairing would lead to further reduction in the cylinder wake from what is shown in the lower Reynolds number experiments. From the PIV results, it appeared that there were few differences between the performances of the C30u and E863 airfoils. At 0 deg, the C30u appeared to perform slightly better than the E863, whereas at 10 deg, both airfoils appeared to have approximately equal performances.