Control of boundary layer flow on wind turbine blades by active methods

In this study, it is aimed to increase the aerodynamic performance of a wind turbine blade by using the suction technique which is one of the active control methods of boundary layer flows based on the principle of air intake from the boundary layer into the blade. Suction is defined as a continuous jet and the S809 airfoil is preferred which is widely used in wind turbine applications as a blade model. Two different numerical studies were carried out in this study and three different jet positions (Ljet = 0,1c, 0,26c, 0,36c) and three different jet velocity ratios (Rjet = 0,1, 0,3, 0,5) were selected as the parameters of the first numerical study. Four different angles of attack (α=8°, 10°, 12°, 14,24°), nine different jet positions (Ljet=0,1c, 0,2c, 0,3c, 0,45c, 0,5c, 0,54c, 0,55c, 0,72c, 0,945c) and three different jet velocity ratios (Rjet=0,1, 0,2, 0,3) were selected as the parameters of the second numerical study. For both numerical studies, the width of the suction jet was fixed as 2,5% of the chord length and the angle of the suction jet (θjet) was 90° to the local jet surface. Numerical analyses for two-dimensional, incompressible, steady, turbulent and viscous flow were performed using SST k-ω turbulence model with an angle of attack of α =15° and Re=106 for the first numerical study and angles of attack of α =8°, 10°, 12°, 14,24° and Re=2x106 for the second numerical study. In the first numerical study, firstly, the effect of the suction jet position was investigated and then the effect of the suction jet velocity ratio was examined with an optimum position of the suction jet that showed the best result. When the simulation results of the flow around the airfoil are examined, the best result is obtained when the suction jet position is jet-3 (0,36c) and the suction jet velocity ratio is 0,5. The ratio of CL/CD is increased from 17,92 to 273,03 compared to the no-jet situation. Although it is seen that the suction jet has a positive effect on the aerodynamic performance of the wing, it has been concluded in the second numerical study that the most beneficial jet position and jet velocity ratio are 0,3c and 0,3. If the suction jet position is located close to the trailing edge, the positive effect on the aerodynamic performance of the wing no longer exists. As a result of the analysis carried out in the second numerical study, it can be concluded that the jet position where CL/CD has the highest value in all four different angles of attack was 0,5c. Beyond this position, for example, when the jet position is Ljet=0,55c, CL/CD tends to decrease, regardless of the intensity of the applied suction jet.