Experimental characterization of turbulent boundary layers around a NACA 4412 wing profile Articles uri icon

authors

  • Mallor, Fermin
  • SANMIGUEL VILA, CARLOS
  • Hajipour, Majid
  • Vinuesa, Ricardo
  • SCHLATTER, PHILIPP CHRISTIAN
  • SERPIERI, JACOPO

publication date

  • January 2025

start page

  • 1

end page

  • 12

volume

  • 160

International Standard Serial Number (ISSN)

  • 0894-1777

Electronic International Standard Serial Number (EISSN)

  • 1879-2286

abstract

  • An experimental characterization of the turbulent boundary layers developing around a NACA 4412 wing profile is carried out in the Minimum Turbulence Level (MTL) wind tunnel located at KTH Royal Institute of Technology. The campaign included collecting wall-pressure data via built-in pressure taps, capturing velocity signals in the turbulent boundary layers (TBLs) using hot-wire anemometry (HWA), and conducting direct skin-friction measurements with oil-film interferometry (OFI). The research spanned two chord-based Reynolds numbers (Rec=4×105 and 106) and four angles of attack (5 degrees , 8 degrees , 11 degrees and 14 degrees ), encompassing a broad spectrum of flow conditions, from mild to strong adverse-pressure gradients (APGs), including scenarios where the TBL detaches from the wing surface. This dataset offers crucial insights into TBL behavior under varied flow conditions, particularly in the context of APGs. Key features include the quasi-independence of the pressure coefficient distributions from Reynolds number, which aids in distinguishing Reynolds-number effects from those due to APG strengths. The study also reveals changes in TBL dynamics as separation approaches, with energy shifting from the inner to the outer region and the eventual transition to a free-shear flow state post-separation. Additionally, the diagnostic scaling in the outer region under spatial-resolution effects is considered, showing further evidence for its applicability for small L+, however with inconsistent results for larger L+. The findings and database resulting from this campaign may be of special relevance for the development and validation of turbulence models, especially in the context of aeronautical applications.

subjects

  • Aeronautics
  • Mechanical Engineering

keywords

  • wind-tunnel experiment; hot-wire anemometry; turbulent boundary layer; adverse-pressure gradient; turbulence scaling