1 Risø National Laboratory for Sustainable Energy, Technical University of Denmark2 Department of Wind Energy, Technical University of Denmark
The present work describes a thorough investigation of 2D computations of the flow around a NACA 63-415 aerofoil fitted with stall strips (SS). A mesh study as well as a time step study is carried out and all computations are compared with experiments.Two different SS, 5mm and 7mm are investigated at several positions. Furthermore the influence of laminar to turbulent transition and the effect of a rounded SS were tested. There is not sufficient agreement between the experimental results and thesimulations to draw any conclusions of optimum position and geometry of the SS. The 7mm SS's placed at P00 and P-02 has the greatest effect on the max lift followed by SS P02. The 5mm SS's does, as in the experiment, not change the lift curve noticeably.Even though this investigation does not conclusively succeed in verifying the experimental results with CFD, many useful conclusions can be drawn from the results. It is observed in the experiment that the vertical force fluctuates at higher angles ofattack. This indicates that small bubbles are being shed off the profile causing the force to vary. This property is observed when transition is included in the model and also when the tip of the SS is rounded. From this result it could be concluded thatthe level of turbulence produced on the tip of the SS is very important for the development of the flow downstream. In the sharp tip calculations using fully turbulent computations, this is most likely too high, which resulted in the fine structures beingdamped out, with only one bubble appearing.