Transonic buffet control mechanism of the supercritical airfoil with an oscillating morphing surface

Abstract

Transonic shock buffet arises from a self-sustained interaction between unsteady shock motion and the boundary layer and remains a fundamental challenge in transonic aerodynamics. Recent advances in morphing-surface technology offer new opportunities to manipulate shock wave–boundary-layer interactions actively through surface deformation and oscillation. This study investigates the control mechanism of an oscillating morphing surface (OMS), with particular emphasis on phase coupling between the OMS and shock motion within the present two-dimensional unsteady Reynolds-averaged Navier–Stokes framework. The results indicate that the flow undergoes a transient OMS interference process before reaching an OMS-buffet stage, in which the shock motion is synchronized with the OMS excitation. When the OMS is deployed at the mean shock position, an excitation frequency of 100 Hz reduces the buffet load by 70.92%. Two OMS-buffet states are identified according to the phase relationship between shock excursion and surface motion. The in-phase OMS-buffet is associated with a substantial reduction in buffet load, whereas the anti-phase OMS-buffet shows no consistent suppression tendency. Dynamic mode decomposition analysis reveals that in-phase and anti-phase modal patterns coexist during the interference process and that the OMS preferentially amplifies the mode whose frequency is closest to the excitation frequency, thereby selecting the resulting OMS-buffet state. The physical mechanisms identified in this work provide a unified interpretation of OMS-based buffet control and guidance for active transonic buffet control strategies.