Experimental investigation of flowfield over an iced aerofoil

Wind-tunnel measurements were used to study the characteristics of the unsteady separation bubbles on a NACA 0015 aerofoil with simulated two-dimensional leading-edge glaze ice accretions. The unsteadiness present in the iced-aerofoil flowfield was determined using measurements of the time-dependent aerofoil surface pressure distribution at Reynolds number of 1.0 x 10(6). Additionally, the unsteady flow features were investigated through the power spectrum of the stream-wise velocity fluctuations using a hot-wire anemometry. The results showed that the highest value of root-mean-square fluctuation of the surface pressure consistently occurred upstream of the mean shear-layer reattachment location. Spectral analysis of stream-wise velocity fluctuations near reattachment location revealed evidence of the regular frequency at Strouhal numbers of 0.5-0.63. Moreover, the low frequency oscillations associated with shear-layer flapping was also identified in the wake velocity spectra on the order of 10 Hz that resulted in Strouhal numbers of 0.0186-021.