Steady and Unsteady Plasma Wall Jets for Separation and Circulation Control

Goeksel, Berkant; Greenblatt, David; Rechenberg, Ingo; Nayeri, Christian Navid; Paschereit, Christian Oliver

doi:10.2514/6.2006-3686

Cited by 88 publications

(41 citation statements)

References 11 publications

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“…18a). This agrees with the background literature that clearly supports a sufficient effectiveness of DBD actuation to increase the lift of NACA profile in post-stall regime at the present Reynolds number [1][2][3][4][5][6][7][8]. The change in flow state also induces modifications of the turbulent velocities in the wake region.…”

Section: Time-averaged Velocity F Ieldssupporting

confidence: 89%

“…Previous experimental studies about flow separation controlled by nonthermal plasma actuation have demonstrated that the stall regime can be delayed for NACA 0012 [3], NACA 0015 [4][5][6] or other airfoils profiles [7,8] (Reynolds number up to 4 × 10 5 ). Plasma actuators are attractive for aerospace and MAVs applications because they are simple, lightweight and constitute low-cost devices.…”

Section: Introductionmentioning

confidence: 98%

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On the Vortex Dynamic of Airflow Reattachment Forced by a Single Non-thermal Plasma Discharge Actuator

Bénard

Moreau

2011

Flow Turbulence Combust

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Commercial and military aircrafts or miniature aerial vehicles can suffer from massive flow separation when high angles of attack are required. Single dielectric barrier discharge (DBD) actuators have demonstrated their capability of controlling such a separated flow at low external velocity. However, the processes resulting in the improvement of the flight performances remain unclear. In the present study, the reattachment process along the suction side of a NACA 0015 placed at an angle of attack of 16 • is experimentally investigated for an external velocity of 20 m/s (Re = 260,000). A single DBD actuator is mounted at the leading edge of the model. The velocity fields above the suction side of the airfoil are measured by a high-speed acquisition system (3 kHz). The results indicate that the baseline flow presents shed vortices that form at the leading edge and linearly grow along the free shear layer axis. This vortex shedding is organized and exhibits a specific frequency of about 90 Hz. The continuous actuation produces a partial flow reattachment up to 70% of the chord length. Temporal cross-correlation function indicates the presence of a vortex shedding at the trailing edge of the controlled flow. Finally, the temporal analysis demonstrates that the reattachment process requires 50 ms to reach a stabilized attached flow. The time-resolved analysis of the reattachment suggests that the actuation by plasma discharge acts as a catalyser by reinforcing one of the coherent flow structures already existing in the natural flow.

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Section: Time-averaged Velocity F Ieldssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 98%

On the Vortex Dynamic of Airflow Reattachment Forced by a Single Non-thermal Plasma Discharge Actuator

Bénard

Moreau

2011

Flow Turbulence Combust

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“…In addition, it has been clarified that the use of unsteady actuation gives a better of capability to the separation control compared with steady actuation [29,31,32]. The unsteady actuation is called the "burst mode" in this study, and the steady actuation is called the "normal mode."…”

mentioning

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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“…The first applications involved external flows, such as around aircraft wings [1,2] operating at atmospheric temperatures and at or below atmospheric pressures. Baughn et al [3] and Porter et al [4] measured SDBD actuators' forces at atmospheric conditions.…”

mentioning

confidence: 99%