Morteza Ramezani - Faculty of new sciences and technologies, University of Tehran, Tehran, Iran
Mohammad Moshfeghi - Department of Mechanical Engineering, Sogang University, Seoul, South
Nahmkeon Hur - Department of Mechanical Engineering, Sogang University, Seoul, South

The power generation of a wind turbine is severely dependent upon the aerodynamic performance of the blade. Usually, the root or even middle parts of the blade operate at a high angle of attack (AoA). Since the importance of flow control when the blade encounters a separated flow and stall condition, the split passive flow control method is applied on S809 airfoil. This paper studies the effect of two splits simultaneously via the validated three-dimensional DES (detached eddy simulation) turbulence model on an S809 airfoil. Two types of the split that have optimum performance are selected in order to investigate double-split S809 airfoil aerodynamically. The results of the double-split model showthat its behavior mostly follows the behavior of the single-split model with the wider split. However, the narrower split also is positively effective over a limited range of AoAs, and as a result, the double split model’s performance becomes higher than both of the single-split models. Despite the positive effects, however, it was also found that the formation of a separation bubble inside the channel of the double-split model and the interference of outgoing flows from split exits of the two splits are the main negative aspects of the double split configuration. Finally, to avoid these negative effects, a control method has been proposed for the double-split configuration

Wind turbine, DES simulation, split airfoil, passive flow control method