Control of turbulent separation from an inclined cylinder of finite aspect ratio, thus affecting its yaw

Turbulent flow surrounding a yawed circular cylinder of finite aspect ratio, that was either swept back or swept forward, was investigated experimentally. The cylinder that was capped by an ellipsoid of revolution, contained two small actuators emitting sweeping-jets that were tangential to the surface and orthogonal to the axis of the cylinder. Actuation created large yawing moments capable of overcoming the natural restoring force toward the plane of symmetry. Thus, in the swept-back configuration this experiment is relevant to the control of an aerial refueling boom while in the swept-forward configuration it enables the control of a cylindrical missile type object at large incidence angles. The forces and moments acting on the cylinder at various yaw angles were measured by balance while the interaction between the jets and the flow in the lee of the cylinder was mapped using 2D-Particle Image Velocimetry. Surface flow visualization was used in order to confirm the sensitivity of the flow to the azimuthal location of the actuators at different yaw angles.