Measurement of Unsteady Flow Reattachment on an Airfoil with a Leading-Edge Horn-Ice Shape

By: Phillip J. Ansell

Adviser: Dr. Michael B. Bragg

University of Illinois at Urbana-Champaign, 2012


ABSTRACT
A technique for identifying the unsteady shear-layer reattachment location downstream of an ice shape on an airfoil using an array of surface-mounted hot-film probes is presented. The method utilizes statistical comparison of signals from adjacent probes to identify regions of strong anti-correlation, indicating flow bifurcation at reattachment. In an example, hot-film array measurements were obtained for two airfoil models with simulated leading-edge ice shapes. These hot-film array measurements were used to generate time histories for the unsteady location of shear-layer reattachment downstream of a leading-edge ice shape. The resulting spectral content of the unsteady shear-layer reattachment locations reveal influences of regular-mode vortex shedding and shear-layer flapping. The Strouhal numbers corresponding to these two flow phenomena compared well to those found in literature. Statistical reduction of the unsteady location of reattachment is also consistent with prior work.






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