Characterization of Low-Frequency Oscillations in the Flowfield About an Iced Airfoil

摘要

Wind-tunnel measurements were used to identify and characterize the low-frequency oscillation present in the flowfield about an NACA 0012 airfoil with a horn-ice shape. This low-frequency mode was identified in the unsteady content of the airfoil lift coefficient and the corresponding Strouhal numbers compared well with those reported in the literature. To study the relationship between the ice-induced separation bubble dynamics and the airfoil circulation, the unsteady shear-layer reattachment location was determined using measurements from a surface-mounted hot-film array. At the low-frequency mode, the lift coefficient led the reattachment location by a phase of /2. Additional characterization of the relationship between the unsteady shear-layer reattachment location and the unsteady airfoil pressure distribution was also completed, along with an analysis of the convective qualities of the low-frequency oscillation throughout the airfoil pressure distribution.