Flow control over a circular cylinder using virtual moving surface boundary layer control

Abstract

Flow control study of a circular cylinder is carried out using symmetric dielectric barrier discharge (DBD) plasma actuators at the Reynolds number of 10,000. Here, two symmetric DBD plasma actuators are located at the top and bottom of the circular cylinder, respectively, each of which induces pairs of counter-rotating starting vortices on both sides of exposed electrodes. The downstream starting vortices soon take the form of a wall jet along the freestream direction. On the other hand, the upstream starting vortices interact with the incoming flow remain for some time, bringing in high momentum from the freestream to near-wall region, enabling the boundary layer to withstand the adverse pressure gradient and suppressing the separation around the circular cylinder. The rotating vortical structures around the circular cylinder created by the plasma actuators lead to a reduction in the drag coefficient of up to 25%, providing a similar effect to moving surface boundary layer control (MSBLC). This configuration of symmetric DBD plasma actuator, which is studied for the first time in this investigation, is, therefore, called virtual MSBLC. Our results also indicated that the control effect of virtual MSBLC can be enhanced with an increase in the momentum coefficient of plasma jet. Unlike traditional MSBLC devices, the virtual MSBLC based on symmetric DBD plasma actuators do not have profile drag and are without complicated mechanical systems.

Current state and future trends in boundary layer control on lifting surfaces

“…According to the results, actuation manipulates the shear-layer instabilities and modify the wake patterns remarkably. Although the front DBD actuator contributes more to the increases in lift and lift-to-drag ratio, the proposed dual excitation seems most promising for full-stall control in a wide range of excitation frequencies, as reported by Ebrahimi et al 130 Zhang et al 131 study flow control on a circular cylinder by two symmetric DBD actuators located at the top and bottom surface. Each actuator induces a pair of counter-rotating vortices traveling upstream and downstream.…”

“…Zhang et al 131 study flow control on a circular cylinder by two symmetric DBD actuators located at the top and bottom surface. Each actuator induces a pair of counter-rotating vortices traveling upstream and downstream.…”

Active Control of Bluff-Body Flows Using Plasma Actuators

“…More recently, Zhang et al employed two symmetric DBD plasma actuators in a novel configuration such that plasma formed both upstream and downstream of the exposed electrodes [105]. The covered electrode run the entire circumference of the cylinder as in D'Adamo et al but two short uncovered electrodes running from 88 to 92 • were mounted on the exterior of the cylinder (angles measured from the front stagnation point).…”

Deep Reinforcement Learning for Active Flow Control around a Circular Cylinder Using Unsteady-mode Plasma Actuators

“…To overcome these drawbacks, active flow control (AFC) methods have been introduced due to their advantages of being adaptive to the flow conditions as they can be switched off when flow control is not necessary. Active flow control techniques include: steady suction/blowing [8], acoustic excitation [9], synthetic jets [9], and plasma actuators [10]. Among all these techniques, plasma actuators have received particular attention due to their fast response, their high repetition rate, and their ability to produce zero-mass flux with no moving parts [3].…”

“…Among all these techniques, plasma actuators have received particular attention due to their fast response, their high repetition rate, and their ability to produce zero-mass flux with no moving parts [3]. A drag reduction of approximately 25% is reported in [10] from controlling the flow separation around a circular cylinder using two symmetric plasma actuators at Reynolds number of 10000. In addition to flow control, plasma actuators demonstrate great capabilities in other control tasks such as noise-reduction [11], and transition-delay [12].…”