Aerodynamic performance gains in transonic regime on an A320 morphing wing at Reynolds number of 4.5 million through numerical simulation
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A morphing wing prototype of an A320 wing, having a 70 cm chord length, an angle of incidence of 1.8°, an upstream Mach number of 0.78, and a Reynolds number of 4.5 million is examined through Hi-Fi numerical simulations (figure 1) as part of the HORIZON-2023-2027-PATHFINDER- Open Project N° 101129952-BEALIVE-"Bioinspired Electroactive multiscale Aeronautical Live skin", http://horizon-europe-bealive.eu/. This investigation focuses on testing different actuation zones located both upstream and downstream of the shock position to mitigate buffet effects (figure 2), using a Traveling Wave (TW) approach that model a "live-skin" surface in experiments. The deformation of the grid applied for the TW has been treated using the Arbitrary Lagrangian-Eulerian [1] method in the Navier-Stokes Multi Block CFD solver. The OES - Organised Eddy Simulation turbulence modelling approach [2, 3], able to capture the physical development of coherent structures and their interaction with the chaotic turbulence, has been employed. This study highlights the significant feedback effect of the near-wake unsteadiness on the SBLI region and further upstream. The morphing manipulates the downstream unsteadiness, specifically attenuates the shear layer instability and the effect of the associated Kelvin-Helmholtz and von Kármán vortices (figures 1 and 3). A large parametric study has been performed in respect of wavelength (λ), vibration frequency (f), amplitude (a) and application zone [4]. Particular attention was paid to configurations where the actuation zone began upstream or overlapped the shock region (Figure 2) to directly influence the separation bubble under the shock foot and near-wake structures. A remarkable outcome of this study was the identification of an optimal configuration using λ = 3 and λ = 6 cm, f = 750 Hz and low amplitude of 0.3 mm in the green zone (from x/c = 0.514 to x/c = 0.686), which led for the first time in the state of the art to a simultaneous lift increase and drag reduction of (+0.85%) and (−2.3%), respectively and to an improved aerodynamic efficiency (Cl/Cd) of +2.65%, a 91.7% accompanied to a practically total reduction in the lift rms (from 0.06 to 0.005) due to mitigation of the transonic buffet, (Figure 4). These facts are obtained thanks to a downstream shift and weakening of the shock accompanied by a significant attenuation of the spectral energy in the wake, indicating reduced generation of trailing edge noise.
