Effect of unequal flapping frequencies on flow structures

Fenercioglu I., Cetiner O.

AEROSPACE SCIENCE AND TECHNOLOGY, cilt.35, ss.39-53, 2014 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 35
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1016/j.ast.2014.02.007
  • Dergi Adı: AEROSPACE SCIENCE AND TECHNOLOGY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.39-53
  • Anahtar Kelimeler: Pitching and plunging airfoil, PIV, Unequal oscillating frequency, OSCILLATING AIRFOIL, DYNAMIC STALL, WAKE, GENERATION, EFFICIENCY, PROGRESS, DESIGN, THRUST, FIELD, FOILS
  • İstanbul Teknik Üniversitesi Adresli: Evet

Özet

The effects of unequal pitching and plunging frequency on the flow structures around a flapping airfoil is investigated using the Digital Particle Image Velocimetry (DPIV) technique in the reduced frequency range of 0.31 4 <= k <= 6.26 corresponding to Strouhal number range of 0.1 <= St <= 1.0. The SD7003 airfoil model undergoes a combined flapping motion where the pitch leads the plunge with a phase angle of 90 in a steady current. The investigated cases are classified into five flow structure categories based on instantaneous and averaged vorticity patterns and velocity fields around and in the near-wake of the airfoil while the frequency of plunging motion was kept the same as the frequency of pitching motion. Example cases for each category were then investigated for unequal pitching and plunging frequencies and it is observed that employing unequal pitching and plunging frequencies for an oscillating airfoil may result in a change of flow structure category. (c) 2014 Elsevier Masson SAS. All rights reserved.