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Title: Dielectric barrier plasma dynamics for active control of separated flows

Abstract

The dynamics of separation mitigation with asymmetric dielectric barrier discharges is explored by considering the gas flow past a flat plate at an angle of attack. A self-consistent model utilizing motion of electrons, ions, and neutrals is employed to couple the electric force field to the momentum of the fluid. The charge separation and concomitant electric field yield a time-averaged body force which is oriented predominantly downstream, with a smaller transverse component towards the wall. This induces a wall-jet-like feature that effectively eliminates the separation bubble. The impact of several geometric and electrical operating parameters is elucidated.

Authors:
; ;  [1];  [2]
  1. Computational Plasma Dynamics Laboratory, Mechanical Engineering, Kettering University, Flint, Michigan 48504 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20778843
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 88; Journal Issue: 12; Other Information: DOI: 10.1063/1.2187951; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ASYMMETRY; BOUNDARY LAYERS; BUBBLES; DIELECTRIC MATERIALS; ELECTRIC DISCHARGES; ELECTRIC FIELDS; ELECTROHYDRODYNAMICS; ELECTRONS; GAS FLOW; IONS; MITIGATION; PLASMA; PLATES; WALL EFFECTS

Citation Formats

Roy, Subrata, Singh, K.P., Gaitonde, Datta V., and Computational Sciences Branch, Air Vehicles Directorate, Air Force Research Laboratory, Wright Patterson AFB, Ohio 45433. Dielectric barrier plasma dynamics for active control of separated flows. United States: N. p., 2006. Web. doi:10.1063/1.2187951.
Roy, Subrata, Singh, K.P., Gaitonde, Datta V., & Computational Sciences Branch, Air Vehicles Directorate, Air Force Research Laboratory, Wright Patterson AFB, Ohio 45433. Dielectric barrier plasma dynamics for active control of separated flows. United States. doi:10.1063/1.2187951.
Roy, Subrata, Singh, K.P., Gaitonde, Datta V., and Computational Sciences Branch, Air Vehicles Directorate, Air Force Research Laboratory, Wright Patterson AFB, Ohio 45433. Mon . "Dielectric barrier plasma dynamics for active control of separated flows". United States. doi:10.1063/1.2187951.
@article{osti_20778843,
title = {Dielectric barrier plasma dynamics for active control of separated flows},
author = {Roy, Subrata and Singh, K.P. and Gaitonde, Datta V. and Computational Sciences Branch, Air Vehicles Directorate, Air Force Research Laboratory, Wright Patterson AFB, Ohio 45433},
abstractNote = {The dynamics of separation mitigation with asymmetric dielectric barrier discharges is explored by considering the gas flow past a flat plate at an angle of attack. A self-consistent model utilizing motion of electrons, ions, and neutrals is employed to couple the electric force field to the momentum of the fluid. The charge separation and concomitant electric field yield a time-averaged body force which is oriented predominantly downstream, with a smaller transverse component towards the wall. This induces a wall-jet-like feature that effectively eliminates the separation bubble. The impact of several geometric and electrical operating parameters is elucidated.},
doi = {10.1063/1.2187951},
journal = {Applied Physics Letters},
number = 12,
volume = 88,
place = {United States},
year = {Mon Mar 20 00:00:00 EST 2006},
month = {Mon Mar 20 00:00:00 EST 2006}
}
  • The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of themore » dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.« less
  • Active control of flow has a wide range of applications. Specifically, mitigation of detachment due to the weakly ionized gas flow past a flat plate at an angle of attack is studied using two asymmetric sets of electrode pairs kept at a phase lag. The equations governing the dynamics of electrons, helium ions, and neutrals are solved self-consistently with charge-Poisson equation. The electrodynamic forces produced by two actuators largely depend on the relative phase between the potentials applied to rf electrodes and distance between them. A suitable phase and an optimum distance exist between two actuators for effective separation control.
  • Dielectric barrier discharge (DBD) plasma actuators have been used to control the flow around a circular cylinder at Re=15 000, where the near-wake structure was studied using time-resolved particle image velocimetry with simultaneous measurements of the dynamic lift and drag forces. It was shown that the vortex shedding was suppressed when the surface plasma placed near the natural separation point was activated in a pulsed mode at nondimensional frequency, f{sub p}{sup +}, above 0.6 with a force coefficient, C{sub p}, greater than 0.05%. Plasma actuator performance on flow control was summarized by mapping the changes in drag and lift fluctuationsmore » as a function of the forcing frequency and the force coefficient. They showed that more than 70% reduction in lift fluctuations was obtained with up to 32% drag reduction at f{sub p}{sup +}=2.0 and C{sub p}=0.32%. Here, narrowing of the wake was observed as the plasma promoted shear-layer roll-ups at the forcing frequency. This, however, did not affect the shear layer on the opposite side of the wake. At nondimensional forcing frequencies less than 0.6, the vortex shedding locked onto a multiple of the plasma frequency to amplify the wake oscillations. This caused more than 85% increase in lift fluctuations with 8% drag increase at f{sub p}{sup +}=0.2 and C{sub p}=0.01%. The efficiency of flow control using DBD plasma was found to be 1%-2% for drag reduction while around 6% for drag increase.« less
  • The characteristic feature of a dielectric barrier discharge (DBD) is the dielectric barrier placed between the electrodes. In the present work, the influence of the dielectric barrier to the properties of a DBD in air was investigated. Spectroscopic characterization of the DBD and electrical measurements were carried out. It was shown that the efficiency of a DBD can be considerably improved by optimizing the dielectric barrier. The dielectric material should possess an appropriate relative permittivity and thickness. For thin dielectric barriers, a high secondary emission coefficient becomes important. Additionally, the use of only one dielectric barrier is advantageous.
  • No abstract prepared.