Experimental study on drag-reduction mechanisms based on the physical characteristic of tip vortex
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摘要: 本文通过风洞实验研究了翼尖涡的物理特征以及诱导阻力的减阻机制。实验中利用3DPIV（三维粒子图像测速技术）技术得到了翼尖涡的物理特征，并基于本文提出并设计的翼尖气动力测量装置，得到了机翼翼尖处的诱导阻力。实验结果表明，机翼翼尖涡的无量纲环量会随机翼迎角及风速的增大而增大。翼尖涡无量纲环量的减小以及翼尖涡与机翼之间距离的增大都会引起诱导阻力的减小。具体而言，通过抑制翼尖涡的无量纲环量，增加翼尖涡与主机翼之间的距离，减小翼尖涡与机翼之间的相互作用，实现机翼翼尖诱导阻力的减阻。Abstract: The drag-reduction mechanisms based on the physical characteristic of the tip vortex are investigated through experiments in the wind tunnel. Through 3DPIV (3D Particle Image Velocimetry) experiments, the physical characteristic of tip vortex is obtained, and the induced drag of wing is calculated based on the aerodynamic force measurement setup of wingtip proposed in this paper. Experimental results show that the non-dimensional circulation of the tip vortex increases with the increasing angle of attack and the wind speed. Meanwhile, with the decrease of the non-dimension circulation of the tip vortex or the increase of the spacing between the wing and the tip vortex, the induced drag becomes smaller and smaller. Specifically, the induced drag reduction can be achieved by inhibiting the non-dimensional intensity of the tip vortex, which weakens the interaction between the main wing and the tip vortex.
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Key words:
- tip vortex /
- physical characteristic /
- induced drag /
- circulation /
- drag reduction
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图 4 6°迎角下机翼尖涡云图
Figure 4. Contour of the tip vortex of wing with the angle of attack at 6°
图 5 不同机翼迎角下的翼尖涡的瞬时速度场和涡量云图
Figure 5. Instantaneous velocity (arrows) and vorticity (color) fields of the tip vortex of wing with different angles of attack
图 6 不同迎角对翼尖涡的无量纲环量的影响
Figure 6. Non-dimensional circulation of vortex structure on wingtip influenced by the angle of attack
图 7 不同风速下的翼尖涡的瞬时速度场和涡量云图
Figure 7. Instantaneous velocity (arrows) and vorticity (color) fields of the tip vortex of the plate wing with different velocities
图 8 不同雷诺数对翼尖涡的无量纲环量的影响
Figure 8. Non-dimensional circulation of vortex structure on wingtip influenced by the Reynolds number
图 11 翼尖涡无量纲环量对诱导阻力系数的影响
Figure 11. Coefficient of induced drag of wingtip influenced by non-dimensional circulation
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