Numerical and experimental study of flow field characteristics of an iced airfoil

摘要

In this paper, characteristics of separated bubbles and unsteady features of flow fields around a glaze-iced airfoil are investigated. The research was performed using both experimental and numerical approaches. The airfoil was a natural laminar airfoil (NLF-0414) and the ice is considered as the glaze accretion. The experimental measurements were carried out using hot-wire anemometry at Reynolds number of 0.5 × 10~6 and angle of attack ranging from 0° to 6°. In numerical calculations, N-S equations were adopted as governing equations and finite-volume technique was employed to solve the equations. Numerical calculations were performed at Reynolds numbers of 0.5 × 10~6 and 1.8 × 10~6. CFD results and experimental data indicated increasing in the bubble length with increasing in airfoil angle-of-attack. The results showed two separated bubbles in different sizes and also unsteadiness behavior of the flow field which led to low frequency oscillation in lift coefficient with the order of 10 Hz. The frequency of the vortex structures observed in the shear layer measured with hot-wire and it is found that the frequency was in the range of 100 Hz. This frequency was reduced with increasing the angle-of-attack. Vortex shedding was also observed at the downstream of the reattachment location.