Blade Design with Passive Flow Control Technologies

This chapter focuses on the application of passive flow control technologies to wind turbine blades. The motivation of using these technologies is always an enhancement of the wind turbine performance (increase of power production, load reduction, noise reduction, etc.) in comparison to the standard blade. Passive flow control solutions can be limited to static add-ons or involve more significant modifications of the blade for dynamic approaches. Furthermore, these technologies can be included in the initial design of the blade or included later as add-ons to improve the performance of an existing blade design. A large number of passive technologies have been proposed for wind turbine applications, although the level of maturity is not the same for all of them ranging from conceptual studies in some cases to commercial products in others. Some representative examples of specific technologies are included in this chapter: vortex generators, static miniflaps, root spoilers, serrations, winglets, passive flaps, and aeroelastic coupling. For each technology, some aspects related to the state of the art, main concept, impact on the wind turbine performance, application, and design have been described. Finally, passive flow control technologies have to be integrated into the design process of wind turbines. To select and properly apply the most suitable technology for each specific problem, the chapter highlights the importance of modeling tools, design methodologies, objectives and restrictions, design parameters, and scale of impact of each passive flow control solution. In addition, from a general point of view, some design guidelines have been mentioned.