Mechanism analysis of high-order harmonics acting on transonic shock buffeting

Periodic oscillations of shock waves in transonic flow fields create very unstable aerodynamic loads that have a big effect on how safe an aircraft is and how well it handles. To elucidate the mechanism of transonic shock buffeting, a jet disturbance method is introduced and used to analyze the evolution of the flow field characteristics. First, the basic characteristics of buffeting are obtained through wind tunnel experiments. Numerical simulations are then conducted using the unsteady Reynolds-averaged Navier–Stokes equation based on the Reynolds stress model. The response of the global flow field to a jet disturbance enables the effects of the jet intervention time, jet withdrawal, and jet intensity to be studied. When the flow field is disturbed, the oscillations of the shock wave on the upper surface slow, and the buffeting load is reduced. An increase in jet strength suppresses the buffeting by preventing the factors that cause this phenomenon from exerting any influence. When the jet intensity exceeds a critical value, a complex multi-vortex structure and high-frequency pressure fluctuations appear at the trailing edge. In the presence of the jet disturbance, special high-order harmonics appear in the frequency spectrum, and high-frequency pressure waves occur in the global flow field. The fluctuating pressure generates high-order harmonics, and the trailing edge is the core position of transonic shock buffeting. The resulting high-frequency pressure waves are transmitted upstream, strengthening the shock wave–boundary layer interaction and causing shock oscillations.