Dynamic Stall Mitigation Using a Deflectable Leading Edge: The IK30 Mechanism

Abstract

One major problem affecting rotor blade aerodynamics is dynamic stall, characterized by a series of events where transient vortex shedding negatively affects drag and lift, leading to abrupt changes in the wing’s pitching moment. The present work focuses on the mitigation of such effects by using a modified NACA0012 airfoil—the NACA0012-IK30 airfoil—previously used for thrust enhancement in flapping propulsion. An experimental rig is designed to study the advantages of a deflectable leading edge on a plunging and pitching wing, more specifically its influence on the aerodynamic coefficients over time. In the first stage, results indicate that the proposed IK30 mechanism does mitigate the stall effects under static conditions, with stall visualization data corroborating it. Regarding time-varying conditions, the data presents the adequacy of the proposed geometry under different plunging and pitching conditions, which, when correctly used, can mitigate or even eradicate the adverse effects of dynamic stall experienced, leading to significant drag reductions and modest lift enhancements. In the absence of a dynamic stall, the movable leading edge can also provide operational advantages, where it does not negatively affect drag or lift but can reduce the pitching moment intensity by indirectly shifting the pressure center. This study contributes to the long-standing discussion on how to mitigate the adverse effects of dynamic stall by providing an innovative yet simple solution.