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基于雨燕翅膀的仿生三角翼气动特性计算研究

COMPUTATIONAL INVESTIGATIONS FOR AERODYNAMIC PERFORMANCE OF BIO-INSPIRED DELTA-WING BASED ON SWIFT-WING

  • 摘要: 针对低雷诺数微型飞行器的气动布局, 设计出类似雨燕翅膀的一组具有不同前缘钝度的中等后掠(\varLambda =50^\circ)仿生三角翼. 为了定量对比研究三角翼后缘收缩产生的气动效应, 设计了一组具有同等后掠的普通三角翼. 为了深入研究仿生三角翼布局的前缘涡演化特性以及总体气动特性, 采用数值模拟方法详细地探索了低雷诺数(Re=1.58\times 10^4)流动条件下前缘涡涡流结构和气动力随迎角的变化规律. 分析结果表明, 前缘钝度和后缘收缩对仿生三角翼前缘涡的涡流强度和涡破裂位置有显著影响. 相对于钝前缘来说, 尖前缘使仿生三角翼上下表面的压力差增大, 涡流强度也更大, 增升作用也更显著. 相对于普通三角翼构型, 仿生三角翼的前缘斜切使其阻力更大, 但后缘的收缩使涡破裂位置固定在此位置, 因此整个上翼面保持低压, 总的升力更大. 由于小迎角时升力增大更明显, 因此仿生三角翼的气动效率在小迎角时明显大于普通三角翼. 这些结论对于揭示鸟类的飞行机理以及未来微型仿生飞行器的气动布局设计具有重要的研究价值.

     

    Abstract: Aiming at aerodynamic configuration for micro aerial vehicle at the low-Reynolds number flow regime, a group of bio-inspired non-slender delta wings (\varLambda =50^\circ) similar to swift wings with different leading edge bluntness was designed. To quantitatively investigate the aerodynamic effect caused by the trailing edge tapering of the delta wing, a set of generic delta wings with the same sweep angle was designed for comparisons. In order to deeply investigate the evolution characteristics of the leading edge vortex and the overall aerodynamic characteristics of the bio-inspired delta wing, the numerical simulation method was used to explore the leading edge vortex structure and the overall aerodynamic characteristics at different angles of attack in detail under low Reynolds number flow (Re=1.58\times 10^4). Computational results show that, the leading edge bluntness and trailing edge tapering have significant effect on the vortex intensity and vortex breakdown position of the leading edge vortex of the generic delta wing and swift delta wing. Compared to the blunt leading edge, the sharp leading edge increased the pressure difference between the upper and lower surfaces, so it has more pronounced vortex intensity and more significant lift enhancement for models with sharp leading edge. Comparing to generic delta wing configuration, the bevel angle of the leading edge of the bio-inspired delta wing results in higher drag, and the trailing edge tapering makes the vortex breakdown position fixed at the trailing edge, so the entire upper wing surface remains at low pressure, resulting in greater overall lift. Since the lift increases more obviously at low angles of attack, the aerodynamic efficiency of the bionic delta wing is significantly greater than that of generic delta wing at low angles of attack. These conclusions are of great values in revealing the flight mechanism of birds and the design of bionic micro aerial vehicles in the near future.

     

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