Study and Control of a wall-bounded NACA 65(1)412 Airfoil at Transitional Re*

Airfoil performance within the transitional Reynolds number regime exhibits nonlinear behavior and strong sensitivity to the locations of laminar separation and turbulent reattachment. The dynamics of these phenomena are influenced by the transition of the separated shear layer.

Due to the shear layer's responsiveness to small perturbations, these flows are suitable for control. Here, experiments on an aspect ratio AR = 3 NACA 65(1)412 airfoil between two end walls were conducted for $-6\leq\alpha\leq12$ and $2\times10^4 \leq$ Re $\leq 8\times10^4$, with and without acoustic forcing. Force balance and two-dimensional PIV measurements were acquired to investigate the airfoil performance and resulting flow fields. Frequency, amplitude, and actuator location sweeps were carried out across different Re. Results showed clear trends for optimal forcing parameters and significant improvements in airfoil performance, with local acoustic forcing producing up to 77\% increase in $\frac{L}{D}$.