Influence of a Nose Perturbation on the Behaviors of the Vortex Flow around a Slender Body at High Incidence

摘要

The influence of a nose perturbation on the vortex flow around a slender body of revolution at high incidence has been studied numerically. A time-invariant space-fixed minute geometric bump was adopted to act as the perturbation, and all computations were performed for subsonic flows at incidence of 50 deg. Numerical results show that only the asymmetrically-distributed perturbation could provoke the original symmetric flow into asymmetry. The perturbation closer to nose apex has stronger influence on the flow. With perturbation moving downstream axially, there is a sensitive axial location existing, where the flow switches over between two opposite vortex patterns. With perturbation being heightened, the sensitive axial location shifts downstream from nose apex, which indicates that the influence of perturbation on the flow is correlative with the ratio of perturbation height to local boundary-layer thickness. The sensitive axial location is a valley for perturbation located to affect the flow. The total influence of perturbation axial location on the flow lies on both the relative positions of perturbation respectively to nose apex and the sensitive axial location.