Numerical Study of Transonic Buffet on a Supercritical Airfoil

The steady/unsteady flow of the BGK No. 1 supercritical airfoil is investigated by the solution of the Reynolds-Averaged Navier-Stokes equations with a two-equation k-ω turbulence model. The dual-time stepping method is used to march in time. Two steady cases ( 71.0=Ma, 396.1=α and 71.0=Ma, 0.9=α) and one unsteady case ( 71.0=Ma, 97.6=α), both with a far-stream 61020Re x = , are computed. The results are compared with experimental data obtained by Lee et al. The mechanism of the self-excited oscillation for supercritical airfoils is explored. The oscillation period calculated based on the mechanism proposed by Lee is consistent with the Fourier analysis of the computed lift coefficient.