Airfoil performance enhancement by suction and pulsed blowing

Wind turbines blades' surface quality degrades with time and, as a result the blade performance significantly decreases. By applying active flow control techniques it is possible to partly or even fully recover the performance to its original state. In the current study, array of 12 suction and pulsed blowing actuators was fitted into an AH93-300 horizontal wind turbine blade section and tested at Reynolds number range between 0.3×10⁶ and 1.5×10⁶. The actuators were installed at the x/c=0.2 chord length. One or two rows of suction holes were tested and a range of inlet pressures resulting in momentum coefficient range up to 0.0078 and excitation Strouhal numbers in the range of 2 to 8. It was found that the AFC improved the performance of the airfoil for all Reynolds numbers and for large range of incidence angles. Improved overall system efficiency was found for Reynolds numbers above one Million and momentum coefficients in the range of 0.0012 to 0.0022. Scaling the SaOB actuation is still an open issue, where the lift increment and drag reductions seem to scale with a combination of the unsteady and steady velocities and the oscillation frequency.