Flow over a Backward-Facing Step Under Controlled-Plasma, Actuator-Induced Perturbations

Stephen, Eric J.; Carter, Nicholas; Leung, C.T.; Sumerel, Clarke; Hsu, Chen-Yang; McLaughlin, Thomas

doi:10.2514/6.2010-4591

Cited by 4 publications

(1 citation statement)

References 8 publications

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“…They have also shown that depending on the forcing mode, the pressure fluctuations on the wall and the mean reattachment point oscillate at the frequency imposed by the plasma actuator. Several other studies have also shown BFS flow control with plasma actuators [83]- [88].…”

Section: Mechanism Of Flow Modificationmentioning

confidence: 88%

Periodic forced flow in a nanosecond pulsed cold atmospheric pressure argon plasma jet

Darny¹,

Bauville²,

Fleury³

et al. 2021

Plasma Sources Sci. Technol.

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This paper is devoted to the study of the argon flow modification in a cold atmospheric pressure plasma jet driven by nanosecond high voltage (HV) pulses, from single to multiple HV shots applications. A schlieren optical bench has been designed in order to visualize the argon flow downstream expansion in quiescent air, for moderate flow rates below 1 standard liter per minute. A coupled approach is used between charge coupled device (CCD) schlieren imaging and intensified CCD (ICCD) plasma plume imaging, both time-resolved. It is shown that the application of only one HV pulse (i.e. single HV shot) is enough to disturb the flow. The disturbed flow exhibits ripple propagation, on a timescale similar to the flow velocity. When operating in double HV shots, the second ionization wave can be used as a probe, to instantly visualize the flow structure any time after the first HV pulse application. For some flow rates, the ripple can increase in amplitude up to the point when it strongly deforms, or even stops, the plasma plume expansion, after which it is entrained by the flow and the plasma plume retrieves its full usual expansion. When a series of HV pulses are applied, the maximal disturbance of the flow is achieved for a certain pulse repetition frequency (PRF), specific of each flow rate. It is associated with ripples alternation in the plasma plume, in a 3D helicallike arrangement. For greater PRF, the ripples progressively vanish, and the flow is clearly less disturbed. Once the ripples have vanished, increasing further the PRF does not change the plasma plume and flow structures. We suggest that the repetitive plasma ignition mechanically forces the flow inside the capillary with consequences on the global flow structure, similarly to a forced backward-facing step flow with actuator.

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Section: Mechanism Of Flow Modificationmentioning

confidence: 88%

Periodic forced flow in a nanosecond pulsed cold atmospheric pressure argon plasma jet

Darny¹,

Bauville²,

Fleury³

et al. 2021

Plasma Sources Sci. Technol.

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Experimental study of separation bubble control behind a backward-facing step using plasma actuators

2014

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POD analysis of flow over a backward-facing step forced by right-angle-shaped plasma actuator

Wang

2016

SpringerPlus

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PurposeThis study aims to present flow control over the backward-facing step with specially designed right-angle-shaped plasma actuator and analyzed the influence of various scales of flow structures on the Reynolds stress through snapshot proper orthogonal decomposition (POD).Methods2D particle image velocimetry measurements were conducted on region (x/h = 0–2.25) and reattachment zone in the x–y plane over the backward-facing step at a Reynolds number of Reh = 27,766 (based on step height and free stream velocity . The separated shear layer was excited by specially designed right-angle-shaped plasma actuator under the normalized excitation frequency Sth ≈ 0.345 along the 45° direction. The spatial distribution of each Reynolds stress component was reconstructed using an increasing number of POD modes.ResultsThe POD analysis indicated that the flow dynamic downstream of the step was dominated by large-scale flow structures, which contributed to streamwise Reynolds stress and Reynolds shear stress. The intense Reynolds stress localized to a narrow strip within the shear layer was mainly affected by small-scale flow structures, which were responsible for the recovery of the Reynolds stress peak. With plasma excitation, a significant increase was obtained in the vertical Reynolds stress peak.ConclusionsUnder the dimensionless frequencies Sth ≈ 0.345 and which are based on the step height and momentum thickness, the effectiveness of the flow control forced by the plasma actuator along the 45° direction was ordinary. Only the vertical Reynolds stress was significantly affected.

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Flow over a Backward-Facing Step Under Controlled-Plasma, Actuator-Induced Perturbations

Cited by 4 publications

References 8 publications

Periodic forced flow in a nanosecond pulsed cold atmospheric pressure argon plasma jet

Periodic forced flow in a nanosecond pulsed cold atmospheric pressure argon plasma jet

Experimental study of separation bubble control behind a backward-facing step using plasma actuators

POD analysis of flow over a backward-facing step forced by right-angle-shaped plasma actuator

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