The interaction between flutter and buffet in transonic flow

This paper presents a kind of nodal-shaped oscillation that is caused by the interaction between flutter and buffet in transonic flow. This response differs from the common limit cycle oscillation that appears in transonic aeroelastic problems. The benchmark active controls technology model with the NACA0012 airfoil is used as the research model. First, both buffet and flutter cases are computed through unsteady Reynolds-averaged Navier–Stokes method and are validated by experimental data. Second, the interaction is found to occur beyond the flutter onset velocity at Mach 0.71. When the pitching angle of a fluttering structure exceeds the buffet onset angle, the high-frequency aerodynamic loads induced by transonic buffet destroy the original flutter model, and then the amplitude of the structure motion decays. When the structural pitching angle is less than the buffet onset angle, the buffet disappears and flutter occurs again. As the process repeats itself, the transonic aeroelastic system displays a nodal-shaped oscillation (divergent–damping–divergent–damping oscillation). Finally, the mechanism of the interaction is discussed by analyzing the energy transportation between the flow and the structure in one cycle of nodal-shaped oscillation, and by observing the variation in the phase-angle difference between the plunging and pitching displacements. In this way, this research provides a new approach to understand flutter suppression.