Unsteady modes in the flowfield about an airfoil with a horn-ice shape

Phillip J. Ansell, Michael B. Bragg

Research output: Chapter in Book/Report/Conference proceedingConference contribution


An experimental investigation was conducted on an NACA 0012 airfoil with a leading-edge horn-ice shape to identify and characterize flowfield unsteadiness related to ice-induced flow separation. This type of iced-airfoil flowfield is dominated by a leading-edge separation bubble, which is associated with several inherent modes of unsteadiness. Using unsteady surface pressure and wake velocity measurements, three distinct modes of unsteadiness were identified at various locations throughout the flowfield. These unsteady modes included a regular mode of vortical motion and a shear-layer flapping mode, which are both associated with separation bubbles. A low-frequency mode was also observed that was associated with the thin-airfoil stall type of the iced airfoil, and was represented by a global oscillation of the airfoil circulation. The characteristic frequencies, convective qualities, and flowfield locations corresponding to these unsteady modes were compared with those reported in the literature for iced-airfoil flowfields and flows about canonical geometries.

Original languageEnglish (US)
Title of host publication44th AIAA Fluid Dynamics Conference
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
ISBN (Print)9781624102899
StatePublished - 2014
Event44th AIAA Fluid Dynamics Conference 2014 - Atlanta, GA, United States
Duration: Jun 16 2014Jun 20 2014

Publication series

Name44th AIAA Fluid Dynamics Conference


Conference44th AIAA Fluid Dynamics Conference 2014
Country/TerritoryUnited States
CityAtlanta, GA

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • Aerospace Engineering


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