Influence of nose-perturbation location on behavior of vortical flow around slender body at high incidence

Abstract

Response of the vortical flow around a slender body of revolution at high incidence to the shift of a single nose perturbation was investigated systematically using numerical methods. A minute geometric bump was employed to act as the nose perturbation, and all computations were performed for subsonic flows at incidence of 50°. The computational results show that the vortical flow is more sensitive to the perturbation located axially closer to the nose apex of a slender body. With perturbation shifting axially downstream away from nose apex, there is a critical axial location appearing. The vortical flow is less sensitive to the perturbation located axially closer to the critical axial location; when perturbation traverses axially around the critical axial location, the vortical flow switches between opposite asymmetric patterns. The eventual influence of perturbation axial location on the vortical flow lies on both its relative locations to nose apex and the critical axial location. The vortical flow is more sensitive to the perturbation located circumferentially farther away from the fore-and-aft symmetric plane of a slender body, and just the asymmetrically-located perturbation can provoke the vortical flow to asymmetry. With perturbation shifting circumferentially in sequence, the vortical flow varies by degrees in manner of a single periodicity. A convective-type of instability existing in the flow field is responsible for the influence of nose perturbation on the vortical flow.