Tip loss correction for Actuator/Navier-Stokes computations

A new tip loss correction, initially developed for ID Blade Element/Momentum (BEM) computations (submitted to Wind Energy), is now extended to 2D Actuator Disc/NavierStokes (AD/NS) computations and 3D Actuator Line/Navier-Stokes (AL/NS) computations. In the paper it is shown that the tip loss correction is an important and necessary step for actuator/Navier-Stokes models. Computed results are compared to experimental data and to results from BEM computations using the new tip correction as well as the original one of Glauert (Aerodynamic Theory, Dover, New York, Chap. VII, Div. L, pp. 251-268). From the results it is concluded that the tip loss correction has been correctly employed in the Navier-Stokes based actuator models. The results also demonstrate that the difference between actuator line and actuator disk-based models may increase, especially for flows at a low tip speed ratio. Since the flows at a low tip speed ratio are too far to be considered as axisymmetrical flows, the actuator disk models that are based on axisymmetrical flow behaviors may not be valid.