The bursting of a laminar separation bubble subject to periodic forcing is studied experimentally on a NACA0018 airfoil at a chord Reynolds number of $7\times {10}^4$. Bursting of the bubble is initiated by a dynamic ramp increase in angle of attack past the static stall angle with a nondimensional pitch rate of 0.008. The initial and final effective angles of attack are $4.9^{\circ }$ and $7.2^{\circ }$. Periodic forcing is continuously applied to the boundary layer by a spanwise-uniform alternating current dielectric-barrier-discharge plasma actuator at the leading edge of the airfoil. The forcing frequency was chosen to match the unforced vortex shedding frequency of the separated shear layer at the initial angle of attack. Surface pressure and particle image velocimetry measurements were obtained during the airfoil motion to investigate the boundary layer development on the suction surface. In the unforced flow, bursting of the laminar separation bubble begins before the maximum angle of attack is reached. The results show that periodic forcing can either delay or prevent the onset of bursting past the end of the pitching motion. With increasing forcing amplitude, the laminar separation bubble may persist at the maximum angle of attack for on the order of 100 convective time units before bursting. Although periodic forcing can delay bursting, the dynamics of the bursting process are largely unchanged once the bursting process initiates, requiring a period of approximately 30 convective time units for the flow to settle to a massively separated state. The delay in the onset of bursting increases and becomes less deterministic as the forcing amplitude increases, until the forcing amplitude is sufficient to prevent bursting entirely.

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• Aerodynamics
• Boundary layer receptivity, stability & separation
• Flow control