Effects of Trailing-Edge Flap on Buffet Characteristics of a Supercritical Airfoil,
NATIONAL AERONAUTICAL ESTABLISHMENT OTTAWA (ONTARIO)
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Buffet characteristics of a 16 thickness-to-cord ratio supercritical airfoil were investigated in the high Reynolds Number two-dimensional test facility of the NAE. The trailing-edge flap dimension was 13.5 chord and it was deflected at various angles to study the effect of modifying the downstream pressure on controlling flow separation over the airfoil. The unsteady normal force was measured and the buffet boundary was determined from the divergence of the fluctuating normal force. The investigation was conducted quite deep into the buffet regime. Spectral analyses of the normal force were carried out and the frequencies of shock wave oscillations were measured. They were found to be Mach number dependent and varied between 50-80 Hz for M 0.612 to 0.792. The effects of varying the flap angles on the shock wave position and drag of the airfoil were also investigated. Results for an off-design Mach number of 0.612 were given in some details.