INFLUENCE OF NOSE PERTURBATIONS ON BEHAVIORS OF ASYMMETRIC VORTICES OVER SLENDER BODY

The influence of nose perturbations on the behaviors of asymmetricvortices over a slender body with a three-caliber ogive nose is studied in this paper.The tests of a nose-disturbed slender body with surface pressure measurement wereconducted at a low speed wind tunnel with subcritical Reynolds number of 1×10~5 atangle of attack α=50°. The experiment results show that the behaviors and struc-ture of asymmetric vortices over the slender body are mainly controlled by manualperturbation on the nose of body as compared with geometrical minute irregularitieson the test model from the machining tolerances. The effect of the perturbation ax-ial location on asymmetric vortices is the strongest if its location is near the modelapex. There are four sensitive circumferential locations of manual perturbation atwhich bistable vortices over the slender body are switched by the perturbation. Theflowfield near the reattachment line of lee side is more sensitive to the perturbation,because the saddle point to saddle point topological structure in this reattachmentflowfield is unstable. Various types of perturbation do not change the perturbationeffect on the behaviors of bistable asymmetric vortices.