Abstract: Transonic buffet is a shock oscillation phenomenon induced by shock wave/boundary layer interaction, which severely compromises aircraft structural safety and aerodynamic performance. This study employs numerical methods to investigate the control efficacy and underlying mechanisms of high-frequency oscillating morphing surfaces on transonic buffet. Systematic computations and analyses are conducted for three morphing surface excitation types across a frequency range of 1–20 times the natural buffet frequency to examine their effects on airfoil buffet response characteristics. The results demonstrate that all three excitation types can effectively suppress buffet loads, with the convex excitation type achieving optimal suppression effect across the entire frequency band, reducing buffet loads by up to 88.49%. Each excitation type exhibits a critical excitation frequency threshold. Beyond this value, frequency lock-in occurs in the flow field, and the shock buffet on the airfoil surface transitions from low-frequency large-amplitude motion (unlock-in state) to high-frequency small-amplitude motion (lock-in state), yielding substantial buffet load reduction (>80%). Modal analysis results further reveal that the transition between lock-in and unlock-in states stems from the competition between the intrinsic buffet mode and the excitation-induced mode. In the unlock-in state, the intrinsic buffet mode dominates the flow field with limited suppression efficacy. In the lock-in state, the excitation-induced mode becomes dominant, compelling the shock motion to shift to higher frequencies and achieving effective control. This study demonstrates the application potential of high-frequency oscillating morphing surfaces for transonic buffet control and provides theoretical foundations for buffet active control strategies based on oscillating morphing surfaces.

Key words: Transonic buffet, Morphing surface, High-frequency oscillating, Buffet suppression, Flow mode