Numerical Simulation and Modelling of a Morphing Supercritical Airfoil in a Transonic Flow at High Reynolds Numbers

Abstract

The flow dynamics and their morphing modification concerning the transonic flow around an Airbus A320 airfoil have been investigated via 2D simulations at a high Reynolds number. A distinctive flow topology, organised and chaotic occurs in this regime driven by appearance of coherent structures such as the Von-Kármán instability as well as the Kelvin-Helmholtz instability. When the Mach number and angle of attack both belong to a certain range of values, the shock wave develops a low-frequency motion along a specific distance on the suction side, issued from the development of transonic buffet instability. This phenomenon is crucial for the design because it leads to a high rise of drag and can trigger in extreme conditions dangerous dip-flutter modes. Electroactive morphing of the trailing edge region achieved by optimal vibration of piezo-actuators has proved capable to create vortex breakdown of the coherent structures and to act through an eddy-blocking mechanism to a considerable thinning of the shear layers and of the wake as has been proven in subsonic regime as shown by Scheller et al. (2015). The eddy-blocking effect in the transonic regime has been studied in the present article in cruise-speed the conditions, following the studies by Szubert et al. (2015) and Hunt, Eames, and Westerweel (2008). Accordingly, computations have been made to determine which type of actuation offers the best performance in terms of buffet dampening and aerodynamic efficiency as a whole. Lastly, it is shown that a flapping motion of the trailing edge can lock-in the frequency of the buffet phenomenon at the flapping frequency, which has potentially useful applications in terms of controlling and reducing shock oscillations.