3D Analysis of the Boundary Layer on Wind Turbine Blades

In this paper، three-dimensional boundary layer flows on wind turbine blades as well as separation event have been studied. At first، boundary layer and three-dimensional momentum integral equations were obtained for incompressible flow considering rotation effects. Next، the effects of pitch angle and the angle between the flow direction and rotation vector on the Coriolis terms were applied using geometry factor definition and Blade Element Momentum (BEM) theory. Then، the integral parameters and effective geometry factors on separation positions and stall structure were investigated for a rotating blade. The obtained results show that rotational ratio، aspect ratio and radial position are three basic parameters for separation occurrence and separation and stall can be delayed via controlling them. Moreover، the results show that the area near the root is strongly influenced by rotational effects. In addition، it is concluded that the centrifugal pumping due to rotation decreases the boundary layer thickness and delays separation especially in the near root region and increases the blade aerodynamic coefficients.