馬蹄渦(英語:horseshoe vortex)是一種簡化的機翼渦系模型,由跟隨機翼運動的等環量附着渦(bound vortex)和在左、右翼尖處形成的翼尖渦組成。這三條渦線形成類似馬蹄的形狀,馬蹄渦也因之得名。[1][2]此外,當機翼在流場中從靜止開始起動時,另有一起動渦從機翼後脫落,但很快因黏性而耗散。[3]同時,遠離飛行器的翼尖渦也同樣因此而耗散。

機翼等升力分佈下形成的馬蹄渦
升力突變導致了突變處形成新渦線
真實升力分佈下形成的複雜渦線

翼尖渦會導致下洗氣流的產生,進而引起誘導阻力[4]

馬蹄渦模型假設環量沿翼展不變(此時由庫塔-儒可夫斯基定理可知升力亦沿翼展不變),但這與實際情形並不相符。在更接近實際的升力線理論中,旋渦強度沿翼展方向不斷變化,強度的改變導致渦從整個機翼後緣脫落形成渦面,而非僅在左、右翼尖處形成渦線。[5]

參考文獻

  1. ^ Millikan, Clark B., Aerodynamics of the Airplane, Figure 1.35
  2. ^ McCormick, Barnes W., Aerodynamics, Aeronautics, and Flight Mechanics, Chapter 3
  3. ^ Shed Vortex. NASA Glenn Research Center. [April 11, 2015]. (原始內容存檔於2015-04-06). 
  4. ^ McCormick, Barnes W., Aerodynamics, Aeronautics, and Flight Mechanics, Chapter 4
  5. ^ McCormick, Barnes W., Aerodynamics, Aeronautics, and Flight Mechanics, Figure 4.21
  • Anderson, John D. (2007), Fundamentals of Aerodynamics, Section 5.3 (4th ed.), McGraw-Hill, New York NY. ISBN 978-0-07-295046-5
  • Clancy, L.J. (1975), Aerodynamics, Section 8.10, Pitman Publishing Limited, London ISBN 0-273-01120-0
  • Cook, N.J. (1985), The designer's guide to wind loading of building structures, Part 1, Butterworths, London ISBN 0-408-00870-9
  • McCormick, Barnes W., (1979), Aerodynamics, Aeronautics, and Flight Mechanics, John Wiley & Sons, Inc. New York ISBN 0-471-03032-5
  • Millikan, Clark B., (1941), Aerodynamics of the Airplane, Section 1-6 John Wiley and Sons, Inc., New York
  • Penwarden, A.D., Wise, A.F.E., (1975) Wind environment around buildings, HMSO, London ISBN 0-11-670533-7.
  • Piercy, N.A.V. (1944), Elementary Aerodynamics, Article 213, The English Universities Press Ltd., London.
  • Von Mises, Richard, (1959), Theory of Flight, Chapter IX - section 4, Dover Publications, Inc., New York ISBN 0-486-60541-8