Spectral Analysis of Vortex Growth and Breakdown over a Delta Wing

A series of subsonic wind tunnel tests was carried out on a coplanar wing-canard configuration at an angle of attack range from 10 to 30 degrees. In this experiment, a 60° swept canard was placed in front of a 60° swept main delta wing. The results of surface pressure distribution show that the presence of canard, delays the vortex formation and growth on the wing to some higher angles of attack comparing to the canard-off case. Due to the downwash of the canard, the wing operates at lower effective angles of attack and therefore, the vortex breakdown is delayed. Spectral Analysis is also applied to the time histories of the unsteady wing surface pressure distribution. The power spectrum Results show the existence of narrow, dominant frequency band containing the majority of the fluctuation energy.