Experimental analysis on oscillations of vortex breakdown location over delta wing

Experiments of flow visualization and dynamic pressure measurement were carried out in a water channel and a wind tunnel respectively to research oscillations of the vortex breakdown location over delta wings. Based on statistics and spectral analysis location of vortex breakdown on video picture of flow visualization , result shows that there are two nondimensional primary frequencies. One of them is equal to 0.07 which is a transition frequency of spiral-bubble-spiral form of vortex breakdown, the other primary frequency is at 0.2~0.4 which is the oscillation frequency of spiral breakdown location with smaller amplitude. By correlation analysis of statistical breakdown location data it indicates that there is a negative correlation between signals of left and right vortex breakdown location after low pass filter. Based on dynamic pressure measurement of different station along wing surface under the identical vortex, it is found that there is a strong positive correlation between oscillation signals of pressure by low pass filter.