Burst Frequency Effect of DBD Plasma Actuator on the Control of Separated Flow over an Airfoil

Asada, Keiichi; Fujii, Kozo

doi:10.2514/6.2012-3054

Cited by 12 publications

(15 citation statements)

References 21 publications

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“…In these studies [7,11,12,15,24,32,33], the optimum burst frequency was suggested to be 0.2-2.0, which was nondimensionalized by the freestream velocity and characteristic length scale (F f c ref ∕u ∞ ). On the other hand, Asada and Fujii [35] have shown that a nondimensional burst frequency F 6 is more effective than F 1. They suggested that the actuation with F 6 can promote the transition to turbulence at the laminar-separation shear layer more effectively; then, the turbulent mixing leads to an early reattachment of the flow.…”

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confidence: 96%

Multifactorial Effects of Operating Conditions of Dielectric-Barrier-Discharge Plasma Actuator on Laminar-Separated-Flow Control

et al. 2015

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A substantial number of large-eddy simulations are conducted on separated flow controlled by a dielectric barrier discharge plasma actuator at a Reynolds number of 63,000. In the present paper, the separated flow over a NACA 0015 airfoil at an angle of attack of 12 deg, which is just poststall, is used as the base flow for separation control. The effects of the location and operating conditions of the plasma actuator on the separation control are investigated by a parametric study. The control effect is evaluated based on the improvement of not only the lift coefficient but also the drag coefficient over an airfoil. The most effective location of the plasma actuator for both lift and drag improvement is precisely confirmed to be upstream of the natural separation point. Even a low burst ratio is found to be sufficient to obtain the same improvements as the cases with a high burst ratio. The effective nondimensional burst frequency F is observed at 4 ≤ F ≤ 6 for the improvement in the lift coefficient and at 6 ≤ F ≤ 20 for that in the drag coefficient.The lift/drag ratio shows a clear peak at 6 ≤ F ≤ 10. To clarify the mechanism of the laminar-separation control, the effect of a turbulent transition is investigated. There is a clear relationship between the separation control effect and the turbulent transition at the shear layer. An earlier and smoother transition case shows greater improvements in the lift and drag coefficients. Flow analyses show that the cases with early and smooth turbulent transition can attach the separated flow further upstream, resulting in a higher suction peak of the pressure coefficient. In addition, another mechanism of the separation control is observed in which the lift coefficient is improved, not by the reattachment through the turbulent transition but by the large-scale vortex shedding induced by the actuation. It is possible to separate these two dominant mechanisms based on the effect of the turbulent transition on the separation control. Nomenclature a = speed of sound BR = burst ratio C D = drag coefficientlength scale D c = ratio between electrostatic body force added by plasma actuator and dynamic pressure D c;effe = effective D c value E i = electric field vector induced by plasma actuator e = total energy per unit volume F base = nondimensional base frequency for sine wave of input voltage; f base c∕u ∞ F = nondimensional frequency of burst wave; f c∕u ∞ f = frequency f base = base frequency for sine wave of input voltage f = frequency of burst wave M ∞ = freestream Mach number Pr = Prandtl number p = pressure Q c = electric charge q i = heat flux vector Re = Reynolds number St = Strouhal number S Suzen = body force vector determined from Suzen model S i = body force vector; Q c E i T = burst wave period T base = period of sine wave T off = period when sine wave switch is off during burst wave period T on = period when sine wave switch is on during burst wave period t = time u = velocity in chord direction . Member AIAA. Article in Advance / 1 AIAA JOURNAL Downloaded by U...

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Multifactorial Effects of Operating Conditions of Dielectric-Barrier-Discharge Plasma Actuator on Laminar-Separated-Flow Control

et al. 2015

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“…Because of its simple structure and high responsivity, it have been received a lot of attention as the perspective control device, and many researches have proved the applicability of the plasma actuator for controlling separated flows around fluid machinery. [1][2][3][4][5] Since flowfields around stationary airfoils are main target of separation control in most of the previous studies, the discussions on the effectiveness of the plasma actuator on the dynamic flowfields around the moving airfoils had been limited. 6-10 Mitsuo et al 9 concludes that the lift enhancement during the pitching down is achieved by that the vortices generated by the plasma actuator bring entrainment of main flow.…”

Section: Introductionmentioning

confidence: 99%

Control of Dynamically Stalled Flowfield around a Pitching Airfoil by DBD Plasma Actuator

Fukumoto

Aono

Tanaka

et al. 2016

8th AIAA Flow Control Conference

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Effects of plasma actuator on the dynamically stalled flowfield with Re = 2.56×10 5 around a pitching NACA0012 airfoil have been investigated by large-eddy simulations (LESs) with sufficient computational spanwise domain length. The dynamically stalled flowfield is characterized by laminar separation bubble, dynamic stall vortex and fully separated flowfield and the current LESs show good agreements with the experimental results with and without plasma actuator. With plasma actuator, the lift coefficient CL during the pitching down is significantly enhanced by the induced large leading edge vortex, whereas the drag coefficient CD is also increased.

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“…This is especially problematic in high-speed flows appearing in real applications. Two approaches have been proposed to overcome this problem: one is to use a burst signal for the driving voltage signal (hereafter referred to as the burst mode) (Asada and Fujii, 2012), the other is to use the PA as a device to generate vortices, i.e., a vortex generator-type plasma actuator (VG-PA), as shown in Fig. 2 (Jukes and Choi, 2013).…”

Section: Introductionmentioning

confidence: 99%

Suppression of vortex shedding from a pantograph head using vortex generator-type plasma actuators

Gejima

Takinami

Fukagata

et al. 2015

JFST

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A vortex generator (VG) is one of the most successful devices used for suppression of flow separation. A conventional VG is a passive control device, so that it may suffer from an inherent drag penalty. As an alternative, we use a dielectric-barrier-discharge plasma actuator (PA) as a VG. Since few studies have been made on such a vortex generator-type plasma actuator (VG-PA), many questions still remain open, e.g., the effectiveness and the performance of the VG-PA for suppression of vortex shedding from a bluff body. In the present study, we experimentally evaluate the performance of the VG-PA by applying it to a pantograph head model of high-speed trains. The Reynolds number based on the freestream velocity and the width of the pantograph head model is 7200. The spanwise velocity induced by the VG-PA is about 33% of the freestream velocity. The flow field is measured by using particle image velocimetry. The present results show that the vortex shedding from a pantograph head model can significantly be suppressed by the VG-PA, which amounts to about 60% reduction in the transverse velocity fluctuations. It is also shown that a burst discharge control significantly improves the control effect in the single-side configuration, in which the vortex shedding is not much suppressed in the continuous mode.

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Burst Frequency Effect of DBD Plasma Actuator on the Control of Separated Flow over an Airfoil

Cited by 12 publications

References 21 publications

Multifactorial Effects of Operating Conditions of Dielectric-Barrier-Discharge Plasma Actuator on Laminar-Separated-Flow Control

Multifactorial Effects of Operating Conditions of Dielectric-Barrier-Discharge Plasma Actuator on Laminar-Separated-Flow Control

Control of Dynamically Stalled Flowfield around a Pitching Airfoil by DBD Plasma Actuator

Suppression of vortex shedding from a pantograph head using vortex generator-type plasma actuators

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