CFD–RANS analysis of the rotational effects on the boundary layer of wind turbine blades

Abstract. The flow field past the rotating blade of a horizontal axis wind turbine has been modeled with a full 3–D steady–RANS approach. Flow computations have been performed using the commercial finite–volume solver Fluent. A number of blade sections from the 3–D rotating geometry were chosen and the corresponding 2–D flow computations have been carried out for comparison, for different angles of attack and in stalled conditions. In order to investigate the effects of rotation a postprocessing tool has been developed, allowing the evaluation of the terms in the boundary layer equations. Examples of the output are proposed for the analyzed flow situations. The main features of the boundary layer flow are described, for both the rotating blade and the corresponding 2–D profiles. Computed pressure distributions and aerodynamic coefficients evidence less lift losses after separation in the 3–D rotating case, mostly for the inward sections of the blade and the highest angles of attack, in agreement with the literature