Investigation of the aerodynamic performance increase in transonic flow over an A320 morphing airfoil by numerical simulation at high Reynolds number
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The present study focuses on a morphing A320 wing prototype with a 70 cm chord length, incidence of 1.8°, upstream Mach number of 0.78 and Reynolds number 4.5 x 106. The study is part of the the HORIZON-2023-PATHFINDER-Open-Project N° 101129952-BEALIVE - "Bioinspired Electroactive multiscale Aeronautical Live skin". This study aims at exploring actuation surfaces beyond the most downstream position of the shock in respect of buffet, creating a “live-skin” surface through a Traveling Wave (TW) approach (Figure 1). A large numerical parametric study is conducted to identify optimal frequency, amplitude and wave-length ranges of the TW in respect of aerodynamic performance increase. The grid deformation due to the TW has been handled by the Arbitrary Lagrangian-Eulerian (ALE) method in the CFD solver NSMB (Navier-Stokes Multi Block). The Organised Eddy Simulation (OES) approach has been used for the turbulence modelling, sensitized to coherent structures physical development capturing. The study revealed the development of buffet instability at 1.8° angle of incidence concerning the unactuated (static) case. Furthermore, the research highlighted a significant feedback effect from the near wake unsteadiness towards the Shock Boundary Layer Interaction (SBLI) region and even upstream of it. By enhancing this effect through morphing that manipulates the downstream unsteadiness, (fig.1) specifically the Kelvin-Helmholtz and von Kármán vortices, the study demonstrated that this morphing effectively reduces the wake thickness and suppresses the buffet instability (fig.2) yielding a drag reduction in the order of 6% and a lift-to-drag increase of 2.5%.
