Effect of partial flexibility over both upper and lower surfaces to flow over wind turbine airfoil

GENÇ M. S., AÇIKEL H. H., Koca K.

ENERGY CONVERSION AND MANAGEMENT, cilt.219, 2020 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 219
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1016/j.enconman.2020.113042
  • Dergi Adı: ENERGY CONVERSION AND MANAGEMENT
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Agricultural & Environmental Science Database, Applied Science & Technology Source, CAB Abstracts, Communication Abstracts, Compendex, Computer & Applied Sciences, Environment Index, INSPEC, Pollution Abstracts, Veterinary Science Database, Civil Engineering Abstracts
  • Anahtar Kelimeler: Airfoil, Flow control, Flow stability, Laminar separation bubble, Partial flexibility, LAMINAR SEPARATION BUBBLE, MEMBRANE WINGS, REYNOLDS-NUMBERS, BLADE PROFILES, AEROMECHANICS, AERODYNAMICS, PERFORMANCE, TRANSITION, AEROFOIL
  • Abdullah Gül Üniversitesi Adresli: Hayır

Özet

Fluid-structure interaction phenomena on NACA 4412 airfoil having membrane material which was partially mounted on both its suction and pressure surfaces were experimentally investigated in wind tunnel measurements. Different experiments including Digital Image Correlation, smoke-wire, force measurement, and hot-wire systems were conducted at varying angles of attack, alpha (0 degrees to 24 degrees), and different Reynolds numbers (Re = 2.5 x 10(4), 5 x 10(4) and 7.5 x 10(4)). The controlled case gave benefits of up to 2 times in lift coefficient at lower angles of attack (alpha = 0 degrees - 10 degrees), at the same time drag coefficient decreased. Moreover, the partially flexible airfoil presented high power efficiencies at the pre-stall angles of attack (alpha = 0 degrees - 10 degrees). Using the flexibility caused the shear layer to approach, laminar separation bubble to suppress, and the wake region to shrunk, indicating the high lift force and less drag force production. The membrane vibrated and deformed due to the flow over the airfoil. Then, the membrane vibration caused the flow to trigger, which caused fluid-structure interaction to perform and the laminar separation bubble to shrink. The transition to turbulence formed earlier and these two flow phenomena moved towards upstream, resulting in having fewer flow fluctuations and increasing the flow stability. This ensures important advantages such as enhancement of aerodynamic performance, power efficiency, and decreasing vibration and noise for wind turbine blades.