Improved actuator surface method for wind turbine application

The purpose of this study was to develop an improved actuator surface model for wind turbine analyses. A new actuator surface model based on the lifting line theory has been suggested to eliminate the unexpected induced velocity due to the circulation, as well as to estimate the span-wise and chord-wise variation of the circulation of the blade. In addition, the method developed overcomes the need for tip-loss correction. A fixed wing case was used to validate the proposed method according to the reference line position and the number of chord-wise panels. Additionally, the present method has been validated against other computational results of various wind turbine cases. In this study, the overprediction of the thrust and power coefficients at the hub and tip regions, previously observed in the existing unsteady actuator model, has been eliminated. The ambiguity concerning the location of the reference line has also been eliminated and the ad hoc tip-loss correction widely used in the legacy actuator line/surface model is no longer necessary in this method.