Purpose

This study aims to investigate the morphing concepts able to manipulate the dynamics of the downstream unsteadiness in the separated shear layers and, in the wake, be able to modify the upstream shock–boundary layer interaction (SBLI) around an A320 morphing prototype to control these instabilities, with emphasis to the attenuation or even suppression of the transonic buffet. The modification of the aerodynamic performances according to a large parametric study carried out at Reynolds number of 4.5 × 10⁶, Mach number of 0.78 and various angles of attack in the range of (0, 2.4)° according to two morphing concepts (travelling waves and trailing edge vibration) are discussed, and the final benefits in aerodynamic performance increase are evaluated.

Design/methodology/approach

This article examines through high fidelity (Hi-Fi) numerical simulation the effects of the trailing edge (TE) actuation and of travelling waves along a specific area of the suction side starting from practically the most downstream position of the shock wave motion according to the buffet and extending up to nearly the TE. The present paper studies through spectral analysis the coherent structures development in the near wake and the comparison of the aerodynamic forces to the non-actuated case. Thus, the physical mechanisms of the morphing leading to the increase of the lift-to-drag ratio and the drag and noise sources reduction are identified.

Findings

This study investigates the influence of shear-layer and near-wake vortices on the SBLI around an A320 aerofoil and attenuation of the related instabilities thanks to novel morphing: travelling waves generated along the suction side and trailing-edge vibration. A drag reduction of 14% and a lift-to-drag increase in the order of 8% are obtained. The morphing has shown a lift increase in the range of (1.8, 2.5)% for angle of attack of 1.8° and 2.4°, where a significant lift increase of 7.7% is obtained for the angle of incidence of 0° with a drag reduction of 3.66% yielding an aerodynamic efficiency of 11.8%.

Originality/value

This paper presents results of morphing A320 aerofoil, with a chord of 70cm and subjected to two actuation kinds, original in the state of the art at M = 0.78 and Re = 4.5 million. These Hi-Fi simulations are rather rare; a majority of existing ones concern smaller dimensions. This study showed for the first time a modified buffet mode, displaying periodic high-lift “plateaus” interspersed by shorter lift-decrease intervals. Through trailing-edge vibration, this pattern is modified towards a sinusoidal-like buffet, with a considerable amplitude decrease. Lock-in of buffet frequency to the actuation is obtained, leading to this amplitude reduction and a drastic aerodynamic performance increase.

中文翻译：

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通过高雷诺数数值模拟，在跨音速状态下空气动力学性能比 A320 变形机翼有所提高

目的

本研究旨在研究能够操纵分离剪切层中下游不稳定动力学的变形概念，并能够在尾流中修改 A320 变形原型周围的上游激波-边界层相互作用 (SBLI)，以控制这些变形。不稳定性，重点是跨音速抖振的衰减甚至抑制。根据在雷诺数为 4.5 × 10 ⁶、马赫数为 0.78 以及根据两个变形概念（行波）在 (0, 2.4)° 范围内的各种迎角进行的大型参数研究，对空气动力性能进行了修改和后缘振动）进行了讨论，并评估了空气动力学性能提高的最终好处。

设计/方法论/途径

本文通过高保真 (Hi-Fi) 数值模拟研究了后缘 (TE) 驱动和行波沿着吸力侧特定区域的影响，该区域实际上从冲击波运动的最下游位置开始，根据自助餐并延伸至近TE。本文通过谱分析研究了近尾流中相干结构的发展以及与非驱动情况下的气动力的比较。因此，确定了导致升阻比增加以及阻力和噪声源减少的变形的物理机制。

发现

本研究研究了剪切层和近尾流涡流对 A320 机翼周围 SBLI 的影响，以及由于新颖的变形（沿吸力侧产生的行波和后缘振动）对相关不稳定性的衰减。阻力减少了 14%，升力阻力增加了 8%。对于 1.8° 和 2.4° 的迎角，变形显示出升力增加了 (1.8, 2.5)% 的范围，其中，对于 0° 的迎角，在阻力减小的情况下，获得了 7.7% 的显着升力增加3.66%，空气动力效率为11.8%。

原创性/价值

本文介绍了 A320 翼型的变形结果，翼弦长为 70 厘米，并受到两种驱动类型的影响，最先进的原始驱动类型为 M = 0.78 和 Re = 450 万。这些 Hi-Fi 模拟相当罕见；大多数现有的都涉及较小的尺寸。这项研究首次展示了一种改进的抖振模式，显示出周期性的高升力“平台”，其间散布着较短的升力-下降间隔。通过后缘振动，这种模式被修改为类似正弦波的抖振，振幅显着下降。获得了抖振频率与驱动的锁定，从而导致振幅减小和空气动力学性能的急剧提高。