Control of the Aerodynamic Loads on an Axisymmetric Cylindrical Body at High Incidence using Forebody Bleed Actuation*

Fluidically-controlled variations of the aerodynamic loads on a slender cylinder wire-mounted at high angles of incidence (up to 60o) are investigated in wind tunnel experiments. The loads are effected using azimuthally-segmented aerodynamic bleed actuation through an ogive forebody with variable porosity. The actuation selectively alters the formation of the forebody counter rotating vortex pair to either promote or suppress its asymmetry, and thereby the evolution of the hierarchy of streamwise-successive vortices that form within the separating flow along that side of the cylinder's near wake. The present investigations show that that azimuthally-controlled bleed actuation can selectively strengthen or override the direction and magnitude of side forces that are randomly effected by natural asymmetries of the forebody vortices. Furthermore, changes in axial distributions of streamwise vorticity concentrations along the cylinder the near wake effected by asymmetric bleed patterns can lead to significant imbalance of the aerodynamic side force (and yawing moment) over a range of incidence angles that are comparable to the cylinder's normal and axial loads.