Active–Passive Cooperative Control of Transonic Shock Buffet Flow over Wings

Transonic flight, while aerodynamically efficient, is susceptible to shock buffet—a flow instability causing self-sustained shock oscillations and unsteady loads that limit operational envelopes. This study addresses the complex nature of three-dimensional shock buffet on wings, which, unlike its two-dimensional counterpart, involves both chordwise shock oscillations and spanwise fluctuations. To tackle this multimodal instability, we propose an active–passive cooperative control (APCC) strategy. The scheme synergistically integrates a shock control bump (SCB) for passive suppression of spanwise fluctuations and a trailing-edge flap for active elimination of chordwise oscillations. The SCB has an extended chordwise dimension and narrow spanwise span, which effectively constrains spanwise flow disturbances while imposing negligible adverse effects on cruise aerodynamic performance. The trailing-edge flap is actuated via a data-driven model-free adaptive control strategy, with the lift coefficient adopted as the feedback signal. Numerical simulations of wing sections and swept wings reveal that single active or passive control can only partially mitigate buffet loads. In contrast, the APCC strategy effectively suppresses both instability modes, stabilizes the unsteady flowfield, and markedly alleviates surface pressure fluctuations. This cooperative approach presents a promising path for enhancing the performance and safety of transonic aircraft.