1 Fluid Mechanics, Department of Mechanical Engineering, Technical University of Denmark2 Department of Mechanical Engineering, Technical University of Denmark3 Department of Wind Energy, Technical University of Denmark
A computational model for predicting the aerodynamic behavior of wind turbine airfoil profiles subjected to steady and unsteady motions has been developed. The model is based on a viscous-inviscid interaction technique using strong coupling between the viscous and inviscid parts. The inviscid part is modeled using a panel method whereas the viscous part is modeled by using the integral form of the the laminar and turbulent boundary layer equations and with extensions for 3-D rotational effects. Laminar to turbulent transition can be forced with a boundary layer trip or computed with a modified e9 transition model. Validation of the steady two dimensional version of the code has been carried out against experiments for different airfoil geometries and Reynolds numbers. The unsteady version of the code has been benchmarked against experiments for different airfoil geometries at various reduced frequencies and oscillation amplitudes, and generally a good agreement is obtained. The capability of the code to simulate a trailing edge flap under steady or unsteady flow conditions has been proven. A parametric study on rotational effects induced by Coriolis and centrifugal forces in the boundary layer equations shows that the effect of rotation is to decrease the growth of the boundary layer, delay the onset of separation, and hence increase the lift coefficient and decrease the drag slightly.