Effect of Inflow Turbulence on Transitional Flows in Pitching Airfoils

We investigate the influence of inflow turbulence on laminar separation bubble (LSB) dynamics and dynamic stall in a pitching NACA 0012 airfoil at a Reynolds number of $Re=2 \times 10^5$ using large eddy simulations. Synthetic turbulence is generated using a digital filter method and applied by adding source terms in the governing equations, and is injected upstream of the airfoil. Our initial results indicate that for small length scales, inflow turbulence delays LSB development in the early stages of the pitch-up maneuver but does not significantly alter the timing of LSB collapse or dynamic stall vortex formation. However, this turbulent inflow appears to encourage the expulsion of energetic vortices from the main LSB, influencing downstream flow behavior. These findings highlight the nuanced role of freestream turbulence in LSB dynamics and suggest that turbulence characteristics, i.e. intensity and length scale, may further influence stall behavior under different conditions.