Simulation of airfoil dynamic stall suppression with a burst control blade in a transitional flow regime

The present study numerically analyzed the effect of a passive flow control method to suppress the dynamic stall phenomenon on a NACA 0012 airfoil exposed to a uniform free flow at the transitional Reynolds number of 1.3 x 10(5). A thin blade was mounted on the airfoil's leading edge to control the separation bubble burst. The fluid relations of motion are the unsteady Reynolds-Averaged Navier-Stokes equations, solved implicitly by a second-order finite-volume solver. A three-equation transitional turbulence model with the capability of separation bubble prediction was used. Numerical results for several pressure distributions and aerodynamic coefficients were compared with available experimental results. The agreement was fair, confirming the reliability of the utilized computational method in the stall conditions. Results from the current work demonstrated that the control blade could prevent the separation bubble burst leading to a reduction in the static and dynamic stall effects. The blade caused a delay in the onset of the flow separation and improved the lift and drag coefficients, particularly in the pitch down motion of the airfoil. For the attack angle range between 5o and 15o, a significant dynamic stall control was observed, while at a wider range, the blade effect was low. The dynamic stall is a significant phenomenon resulting in a blade vibration due to the aeroelastic or hydrodynamic effects. The dynamic stall can lead to the flutter phenomenon that may cause the structure to break.