Passive Flow Control of Dynamically Stalled Airfoil Using a Microcylinder

Energy and global warming issues are the two major challenges facing mankind in this century, and wind energy has been emphasized as a renewable energy source with lower cost, more mature technology and higher reliability. This study examined the effects of passive flow control using microcylinders positioned near the leading edge of a dynamically stalling airfoil (S809) at a Reynolds number of 1 × 10⁶ through computational simulations. Optimal control parameters were identified through a comprehensive parametric analysis based on Unsteady Reynolds-Averaged Navier–Stokes calculations. The results revealed that the aerodynamic forces of the system are highly sensitive to both the position and size of the cylinders. Utilizing a set of optimized control parameters led to significant increases in the average lift and drag coefficients, a reduction in the amplitude of aerodynamic force pulsations, and diminished dynamic stall characteristics. A physical analysis of the flow field elucidated the mechanisms of flow control that enhance the aerodynamic performance of the airfoil. Moreover, when the pitch motion parameters were altered to induce a deep stall condition, the effectiveness of the microcylinders’ control was significantly improved.