Aerodynamic control of flow dynamics coupled to a free-flight axisymmetric body
Lambert, Thomas John
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This research focuses on the unsteady flow mechanisms of using aerodynamic flow control at the aft end flow boundary of a bluff body to modify the reciprocal coupling to its wake dynamics. Building on earlier findings at Georgia Tech which demonstrated that fluidic actuation can affect the global aerodynamic forces and moments on a stationary body, the present research hypothesizes that active alteration of the wake of a moving body can enable prescribed modification of the time-dependent aerodynamic loads (forces and moments), and, consequently, can lead to active control of its motion and stability. The present investigations utilize an axisymmetric model integrated with individually-controlled miniature synthetic jet actuators in multiple experimental setups, such as a wire-mounted programmable six degrees of freedom (6-DOF) traverse. The interactions between the actuation and the cross flow are investigated using particle image velocimetry (PIV), hot-wire anemometry, and a real-time motion analysis camera system. The present investigations elucidate aerodynamic control of the coupling mechanisms between the flow and the platform in prescribed motion (in which the effected changes in the flow and the induced aerodynamic loads do not affect the platform motion), and in free flight (in which the induced changes in the flow feedback to the motion). These investigations demonstrate that both open- or closed-loop actuation strategies for enhancement or suppression of the inherent flow coupling can have profound effects on the evolution and stability of the near wake and on the induced unsteady aerodynamic loads on the body.