Vortex Interactions on a Long Slender Body at High Angles of Incidence*

A slender body of revolution experiences large side forces and yaw moments due to flow asymmetry at high angles of incidence. The flow asymmetry is characterized by a pair of asymmetric vortices that form near the nose region; interact with each other and the surfaces downstream. The goal of the present experimental study is to better understand the flow physics associated with vortex asymmetry on long slender bodies at high incidence particularly the initiation, growth, and interaction of vortices. Measurements were carried out on a cone-cylinder body of semi-apex angle 12° and slenderness ratio of 8.  Particle Image Velocimetry results show that the vortices which are symmetric over the cone can develop asymmetry at the cone-cylinder junction. The primary counter-rotating vortex pair initiates at the cone-tip whereas several secondary vortices emanate from the shear layer along the cylindrical body and merge with the primary vortex pair. Various stages of vortex merging were captured in the present study on a long slender body at high angles of incidence.