Plasma Actuators for Bluff Body Flow Control

Abstract

The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 30,000. Using either steady or unsteady actuation, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. In addition, plasma actuator optimization study is performed to improve the flow control efficiency and to reach higher Reynolds number. This part of the research is intended to maximize the body force produced by plasma discharge (steady and unsteady) which is a function of various parameters such as dielectric material, size of electrodes, their overlap, frequency, voltage, etc. Detailed experiments are performed in a controlled environment with no-external-flow condition with several different dielectric materials of various thicknesses. Plasma induced velocity (using glass Pitot probe), body force (using high precision weighing scale), and power dissipation are measured at various voltages and frequencies. Optimal voltage waveform and frequency has been found which resulted in time averaged maximum induced velocity and body force. This has resulted in an order of magnitude improvement of the actuator effect.

Characterization of a High-Frequency Pulsed-Plasma Jet Actuator for Supersonic Flow Control

“…EHD forcing, in the form of dielectric barrier discharges (DBDs), has been the most extensively used for low-speed flow control applications [1]. DBD plasma actuators have been successfully used for separation control on flat plates [2,3], bluff bodies [4,5], and airfoils [6,7] and to induce mixing enhancement of jets [8]. The most common mechanism of plasma flow actuation for supersonic flow control has been the electrothermal heating produced using steady or pulsed glow and arc discharges.…”

Flow structures in flat plate boundary layer induced by pulsed plasma actuator

“…With two actuators on, the effect of steady actuation was not as good as that with four actuators, while the effect of unsteady actuation with two actuators was comparable to that with four actuators. Thomas et al [15] showed that the turbulent intensity of the circular cylinder wake was reduced by 50% with steady actuation. While for unsteady actuation, the turbulent intensity was reduced by 66% and the energy consumption was 25% of that with steady actuation.…”

“…The plasma actuator for aerodynamic flow control can be used for different purposes. Examples include flat plate drag reduction [1,2], airfoil lift enhancement [3,4], separation control [5][6][7][8][9][10][11][12][13], circular cylinder wake control [14][15][16], etc. More details about the applications were described in the review papers by Corke et al [17], Moreau [18], and Jayaraman and Shyy [19].…”

Sensing and control of flow separation using plasma actuators

“…This has been demonstrated on the leading edges of fixed wing sections by Corke et al [3,4] and Post & Corke [5][6][7], on pitching wing sections undergoing dynamic stall by Post [8] and Post & Corke [5][6][7], on turbine blades in a linear cascade by Huang [9], Huang et al [10,11], List et al [12], Suzen et al [13], Rizzetta & Visbal [14] and River [15], and on bluff body wake control by Thomas et al [16,17].…”