Impact of<i>ns</i>-DBD plasma actuation on the boundary layer transition using convective heat transfer measurements

Ullmer, Dirk; Peschke, Philip; Terzis, Alexandros; Ott, Peter

doi:10.1088/0022-3727/48/36/365203

Cited by 10 publications

(9 citation statements)

References 38 publications

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“…The effect of delaying the stall angle and enhancing the peak lift coefficient like that in static flow separation control has not been observed. According to the existing principles on airfoil stall control in static cases by NS-DBD plasma actuation, [28,29] when the flow separation occurs over the airfoil at high α, the NS-DBD actuation employed at the leading edge can induce a strong span-wise vortex at the leading edge shear layer, accompanied with the induced shock wave propagating outward rapidly. The span-wise vortex is attached to the airfoil, keeps growing and moving downstream.…”

Section: Analysis Of Experimental Results and Flow Control Mechanism ...mentioning

confidence: 99%

Dynamic stall control over an airfoil by NS-DBD actuation*

et al. 2020

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The wind tunnel test was conducted with an NACA 0012 airfoil to explore the flow control effects on airfoil dynamic stall by NS-DBD plasma actuation. Firstly, light and deep dynamic stall states were set, based on the static stall characteristics of airfoil at a Reynolds number of 5.8 × 105. Then, the flow control effect of NS-DBD on dynamic stall was studied and the influence law of three typical reduced frequencies (k = 0.05, k = 0.05, and k = 0.15) was examined at various dimensionless actuation frequencies (F + = 1, F + = 2, and F + = 3). For both light and deep dynamic stall states, NS-DBD had almost no effect on upstroke. However, the lift coefficients on downstroke were increased significantly and the flow control effect at F + = 1 is the best. The flow control effect of the light stall state is more obvious than that of deep stall state under the same actuation conditions. For the same stall state, with the reduced frequency increasing, the control effect became worse. Based on the in being principles of flow separation control by NS-DBD, the mechanism of dynamic stall control was discussed and the influence of reduced frequency on the dynamic flow control was analyzed. Different from the static airfoil flow separation control, the separated angle of leading-edge shear layer for the airfoil in dynamic stall state is larger and flow control with dynamic oscillation is more difficult. The separated angle is closely related to the effective angle of attack, so the effect of dynamic stall control is greatly dependent on the history of angles of attack.

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Section: Analysis Of Experimental Results and Flow Control Mechanism ...mentioning

confidence: 99%

Dynamic stall control over an airfoil by NS-DBD actuation*

et al. 2020

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“…The heated volume depends on thermal energy supplying to surrounding air, and thermal energy per second varies by an input voltage magnitude and an excitation frequency, for example. Ullmer et al [25] experimentally investigated the boundary layer transition using the hot-wire and liquid crystal techniques and showed that the excitation frequency of the ns-DBD plasma actuator considerably influences a boundary layer transition point. Additionally, their hot-wire measurements revealed that plasma actuation excites a velocity fluctuation inside the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Thermal Fluctuation Characteristics around a Nanosecond Pulsed Dielectric Barrier Discharge Plasma Actuator using a Frequency Analysis based on Schlieren Images

Ukai

Kontis

2020

Energies

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A thermal fluctuation driven by a burst plasma discharge is experimentally investigated using a frequency analysis based on the Schlieren images. The burst plasma discharge is controlled by an interval frequency fint = 200 Hz and a pulse frequency fB = 3.6 kHz as well as the duration time of the burst event: Ton. A burst feature is defined as a burst ratio BR = Ton/(1/fint). The burst plasma discharge generates a burst-induced hot plume growing above a ground electrode. In a high burst ratio, which is BR = 0.45 and 0.57, the burst-induced hot plume is formed as a wave thermal pattern that is mainly fluctuated at the interval frequency of 200 Hz. Additionally, a maximum fluctuation spot of 200 Hz appears near the edge of an exposed electrode in a low burst ratio, whereas it moves towards the ground electrode in the high burst ratio. The possible scenario is that a relatively strong ionic wind and/or an induced jet generated in the high burst ratio might cause the movement of the maximum fluctuation spot.

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“…Such vortices generated by ns-DBDs also result in the reattachment of the separated flow on an aircraft wing [24]. Additionally, a hot wire experiment by Ullmer et al [23] revealed that a ns-DBD plasma actuator excited velocity oscillations inside a boundary layer. This means that the ns-DBD plasma actuators generate turbulent kinetic energy in the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

“…To understand thermal flow induced under the uniform flow condition, the previous studies attempted to investigate the effects of the thermal perturbation on surrounding air [18,[21][22][23][24]. Komuro et al [21] investigated the effect of the thermal perturbation on flow instability due to a ns-DBD plasma actuator around aerofoil at 20 m/s and showed that the interaction of two different heated structures improved the lift performance of the aerofoil.…”

Section: Introductionmentioning

confidence: 99%

“…The thermal perturbation is associated with the actuation frequency of the ns-DBD plasma actuator, and the actuation frequency influences the boundary layer instability. According to an experimental investigation regarding boundary layer transition by the ns-DBD plasma actuator [23], the boundary layer transition point moves upstream when the actuation frequency increases. Moreover, the thermal perturbation would create coherent vortices that increase the momentum transfer from the freestream flow to the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

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Temporal variation of the spatial density distribution above a nanosecond pulsed dielectric barrier discharge plasma actuator in quiescent air

et al. 2018

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The thermal perturbation caused by a nanosecond pulsed dielectric barrier discharge (ns-DBD) plasma actuator may lead to boundary layer transition. Hence, understanding of the thermal flow induced by the ns-DBD plasma actuator will contribute to the development of an efficient flow control device for various engineering applications. In this study, the spatial density distribution related to the thermal flow was experimentally investigated using both qualitative and quantitative schlieren techniques. The focus of this study is to understand the initial temporal variation of the spatial density distribution above the ns-DBD plasma actuator in quiescent air. The quantitative visualisation showed that a hot plume is generated from the edge of the exposed electrode and moves slightly towards the ground electrode. A possible explanation is that an ionic wind and/or an induced jet leads to the movement of the hot plume. However, the plasma-induced flow (the ionic wind and the induced jet) is generated after the primary plasma discharges; namely, the hot plume does not move immediately after the first plasma discharge. At almost the same time as the movement of the hot plume, consecutive plasma discharges enhance the density of the hot plume; thereafter, the density reaches almost a steady state.

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Impact ofns-DBD plasma actuation on the boundary layer transition using convective heat transfer measurements

Cited by 10 publications

References 38 publications

Dynamic stall control over an airfoil by NS-DBD actuation*

Dynamic stall control over an airfoil by NS-DBD actuation*

Thermal Fluctuation Characteristics around a Nanosecond Pulsed Dielectric Barrier Discharge Plasma Actuator using a Frequency Analysis based on Schlieren Images

Temporal variation of the spatial density distribution above a nanosecond pulsed dielectric barrier discharge plasma actuator in quiescent air

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