Controlled generation of periodic vortical gusts by the rotational oscillation of a circular cylinder and attached plate

Abstract

Understanding the interaction of vortical gusts and unsteady wing kinematics is crucial to the operation of small aircraft in urban or turbulent environments. Studies investigating this interaction require adequate control of a vortical gust generator to consistently produce the desired vortical gusts for study. Previous studies have focused on the pitching or heaving of airfoils to generate vortical gusts. The current study focuses on the characterization of the vortex shedding process for a rotationally oscillating circular cylinder with an attached one-diameter long plate. When this vortical gust generator is actuated in relatively small sinusoidal motions, von Karman vortices can be generated in a controllable and repeatable fashion over a large range of oscillation frequencies that are significantly different than the natural shedding frequency of the static cylinder, and without the generation of any additional unwanted vorticity. Fine tuning of the actuation parameters allows for the control of the vortex strength, frequency, and transverse location.