Control of Transitional and Turbulent Flows Using Plasma-Based Actuators

Abstract

An exploratory numerical study of the control of transitional and turbulent separated flows by means of asymmetric dielectric-barrier-discharge (DBD) actuators is presented. The flow fields are simulated employing an extensively validated high-fidelity Navier-Stokes solver which is augmented with both phenomenological and first-principles models representing the plasma-induced body forces imparted by the actuator on the fluid. Several applications are considered, including suppression of wing stall, control of boundary layer transition on a plate, control of laminar separation over a ramp, and turbulent separation over a wall-mounted hump. Effective suppression of stall over a NACA 0015 airfoil at moderate Reynolds numbers is demonstrated using either co-flow or counter-flow pulsed actuators with sufficiently high frequency. By contrast, continuous actuation (simulated by a steady body force in the phenomenological model) is found to provide little control of separation. For continuous actuator operation, the first-principles approach is needed in order to reproduce the benefits of the inherently unsteady force induced by the plasma actuator. The pulsed-modulated unsteady plasma force is found to be more effective than a monochromatic radio-frequency forcing. These results highlight the greater importance of transition and turbulence enhancement mechanisms rather than pure wall-jet momentum injection for the effective use of DBD devices. As a consequence, meaningful computations require the use of three-dimensional large-eddy simulation approaches capable of capturing the effects of unsteady forcing on the transitional/turbulent flow structure. For a laminar boundary layer developing along a flat plate, a counter-flow DBD actuator is shown to provide an effective on-demand tripping device.

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Document Details

Document Type
Technical Report
Publication Date
Jun 01, 2006
Accession Number
ADA591899

Entities

People

  • Datta V. Gaitonde
  • Miguel R. Visbal
  • Subrata Roy

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Energy and Power Technologies
  • Materials and Manufacturing Processes
  • Weapons Technologies

DTIC Thesaurus Topics

  • Boundary Layer
  • Boundary Layer Transition
  • Computational Fluid Dynamics
  • Computational Science
  • Flow Fields
  • Fluid Dynamics
  • Fluid Flow
  • Fluid Mechanics
  • Hypervelocity Flow
  • Large Eddy Simulation
  • Pressure Distribution
  • Pressure Gradients
  • Radio Frequency
  • Reynolds Number
  • Three Dimensional
  • Turbulent Flow
  • Turbulent Mixing

Fields of Study

  • Physics

Readers

  • Computational Fluid Dynamics (CFD)
  • Fluid Mechanics and Fluid Dynamics.
  • Pulsed Power and Plasma Physics.