Effect of rigid deflection and flexible morphing trailing edge on the transonic buffet phenomenon for a supercritical airfoil

For a large, wide-body civil aircraft, the flow in the cruise phase is typically a transonic flow, and the buffet phenomenon always occurs. The transonic buffet is very important, and its occurrence will reduce aircraft safety. In this study, the rigid deflection and flexible morphing trailing-edge technologies are applied for a supercritical airfoil from a large, wide-body commercial aircraft to investigate different effects on the transonic buffet phenomenon. The deflection angle of the rigid deflection trailing edge is from 3° upward to 3° downward with an interval of 1°, while the deflection angle of the flexible morphing trailing edge is from 1.5° upward to 1.5° downward with an interval of 0.5°. The numerical results show that for the baseline airfoil at the cruise Mach number of 0.8, the buffet onset angle of attack is about 3°. Whether rigid deflection or flexible morphing, the upward deflection can effectively increase the buffet onset angle of attack and the downward deflection is not beneficial to the buffet control. Moreover, compared to the rigid deflection, the flexible morphing with a lower upward deflection angle can delay the buffet onset better. Since the aerodynamic performance is highly dependent on the airfoil camber in the transonic range, the flexible upward morphing trailing edge with less lift loss has significant advantages and potential for future applications in large aircraft engineering.