The aeroelastic effects on the scatter phenomenon of wind-tunnel data

The unsteady Reynolds-averaged Navier-Stokes equations coupled with the k-ω SST turbulence model are solved to obtain the steady and unsteady aerodynamic forces for airfoils and wings. The effects of vibration types and amplitudes on aerodynamic forces of airfoils and wings are studied. The deformation characteristics of a swept wing induced by steady aerodynamic load are presented. It is found that for a vibrating elastic wing at small and medium incidences, its mean aerodynamic loads are almost the same as those obtained from the static one. On the contrary, at high incidences especially around the stall incidence, the vibration may change the mean values. In addition, the larger amplitude is, the larger discrepancy will be. For a swept wing, the steady aerodynamic loads usually lead to the "pitching down" effect on the wing tip which delays the stall compared with a rigid one; But this phenomenon dose not occur on a aeroelastic wing which can induce the separation ahead and trigger the stall. The above conclusions are in good agreement with the scatter characteristics of wind-tunnel data. The reason why the data obtained from wind tunnel and CFD are different is also analyzed. Meanwhile, it can be an explanation for scatter phenomenon of wind-tunnel data, especially for high incidence cases, which remains a puzzle so far.