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Three-dimensional effects on the aerodynamic performance of flapping wings in tandem configuration
Journal of Fluids and Structures ( IF 3.6 ) Pub Date : 2020-04-01 , DOI: 10.1016/j.jfluidstructs.2020.102893 G. Arranz , O. Flores , M. García-Villalba
Journal of Fluids and Structures ( IF 3.6 ) Pub Date : 2020-04-01 , DOI: 10.1016/j.jfluidstructs.2020.102893 G. Arranz , O. Flores , M. García-Villalba
Abstract Direct numerical simulations have been performed to analyze how three-dimensional effects influence the performance of wings in tandem configuration undergoing a two-dimensional optimal kinematics. This optimal motion is a combination of heaving and pitching of the airfoils in a uniform free-stream at a Reynolds number Re = 1000 and Strouhal number St c = 0 . 7 . Wings of two different aspect ratios, = 2 and 4, undergoing the 2D motion have been considered. It has been found that the interactions between the vortical structures of the fore- and the hind-wings are qualitatively similar to the two-dimensional case for both . However, the ratio between the mean thrust of the hind-wing and the fore-wing decreases from 80% in 2D to 70% in 3D, implying that the 3D effects are detrimental for the vortical interactions between the wings in terms of thrust production. Nonetheless, the propulsive efficiency remains constant both in 2D and 3D, for both . A more realistic flapping motion has also been analyzed and compared to the heaving motion. It has been found that the aerodynamic forces decrease when the wings are in flapping motion. This detrimental behavior has been linked to a sub-optimal motion of the inboard region of the wings. This sub-optimal region of the wings entails a decrease of the mean thrust and of the propulsive efficiency compared to the heaving case, which are more pronounced for the = 4 wings.
中文翻译:
串联配置扑翼气动性能的三维效应
摘要 已经进行了直接数值模拟,以分析三维效应如何影响在二维优化运动学中串联配置的机翼的性能。这种最佳运动是在雷诺数 Re = 1000 和 Strouhal 数 St c = 0 的均匀自由流中翼型的起伏和俯仰的组合。7 . 已经考虑了两种不同纵横比 = 2 和 4 的机翼进行 2D 运动。已经发现,前翅和后翅的涡旋结构之间的相互作用在性质上与两者的二维情况相似。然而,后翼和前翼的平均推力之比从 2D 的 80% 下降到 3D 的 70%,这意味着 3D 效果对机翼之间在推力产生方面的涡流相互作用是有害的。尽管如此,推进效率在 2D 和 3D 中都保持不变。还分析了更真实的扑翼运动并与垂荡运动进行了比较。已经发现,当机翼处于扑翼运动时,空气动力会降低。这种有害行为与机翼内侧区域的次优运动有关。与升沉情况相比,机翼的这个次优区域导致平均推力和推进效率的降低,这对于 = 4 机翼更为明显。还分析了更真实的扑翼运动并与垂荡运动进行了比较。已经发现,当机翼处于扑翼运动时,空气动力会降低。这种有害行为与机翼内侧区域的次优运动有关。与升沉情况相比,机翼的这个次优区域导致平均推力和推进效率的降低,这对于 = 4 机翼更为明显。还分析了更真实的扑翼运动并与垂荡运动进行了比较。已经发现,当机翼处于扑翼运动时,空气动力会降低。这种有害行为与机翼内侧区域的次优运动有关。与升沉情况相比,机翼的这个次优区域导致平均推力和推进效率的降低,这对于 = 4 机翼更为明显。
更新日期:2020-04-01
中文翻译:
串联配置扑翼气动性能的三维效应
摘要 已经进行了直接数值模拟,以分析三维效应如何影响在二维优化运动学中串联配置的机翼的性能。这种最佳运动是在雷诺数 Re = 1000 和 Strouhal 数 St c = 0 的均匀自由流中翼型的起伏和俯仰的组合。7 . 已经考虑了两种不同纵横比 = 2 和 4 的机翼进行 2D 运动。已经发现,前翅和后翅的涡旋结构之间的相互作用在性质上与两者的二维情况相似。然而,后翼和前翼的平均推力之比从 2D 的 80% 下降到 3D 的 70%,这意味着 3D 效果对机翼之间在推力产生方面的涡流相互作用是有害的。尽管如此,推进效率在 2D 和 3D 中都保持不变。还分析了更真实的扑翼运动并与垂荡运动进行了比较。已经发现,当机翼处于扑翼运动时,空气动力会降低。这种有害行为与机翼内侧区域的次优运动有关。与升沉情况相比,机翼的这个次优区域导致平均推力和推进效率的降低,这对于 = 4 机翼更为明显。还分析了更真实的扑翼运动并与垂荡运动进行了比较。已经发现,当机翼处于扑翼运动时,空气动力会降低。这种有害行为与机翼内侧区域的次优运动有关。与升沉情况相比,机翼的这个次优区域导致平均推力和推进效率的降低,这对于 = 4 机翼更为明显。还分析了更真实的扑翼运动并与垂荡运动进行了比较。已经发现,当机翼处于扑翼运动时,空气动力会降低。这种有害行为与机翼内侧区域的次优运动有关。与升沉情况相比,机翼的这个次优区域导致平均推力和推进效率的降低,这对于 = 4 机翼更为明显。