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Richard B. Miles - One of the best experts on this subject based on the ideXlab platform.

  • numerical investigation of nanosecond pulsed plasma actuators for control of shock wave Boundary Layer Separation
    Physics of Fluids, 2018
    Co-Authors: Kiyoshi Kinefuchi, Andrey Starikovskiy, Richard B. Miles
    Abstract:

    This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numerical investigation is undertaken with a large eddy simulation and an energy deposition model for the plasma actuation, in which the dielectric barrier discharge produced plasma is approximated as a high temperature region. The flow characteristics without the plasma actuation correspond to the experimental observation, indicating that the numerical method successfully resolves the shock-wave/Boundary-Layer interaction. With the plasma actuation, complete agreement between the experiment and calculation has not been obtained in the size of the shock-wave/Boundary-Layer interaction region. Nevertheless, as with the experiment, the calculation successfully demonstrates definite difference between the parallel and canted electrodes: the parallel electrode causes excess heating and increases the strength of the interaction, while the canted electrode leads to a reduction of the interaction strength, with a corresponding thinning of the Boundary Layer due to the momentum transfer. The counter flow created by the canted actuator plays an important role in the vortex generation, transferring momentum to the Boundary Layer and, consequently, mitigating the shock induced Boundary Layer Separation.This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numeri...

  • Numerical investigation of nanosecond pulsed plasma actuators for control of shock-wave/Boundary-Layer Separation
    Physics of Fluids, 2018
    Co-Authors: Kiyoshi Kinefuchi, Andrey Starikovskiy, Richard B. Miles
    Abstract:

    This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numerical investigation is undertaken with a large eddy simulation and an energy deposition model for the plasma actuation, in which the dielectric barrier discharge produced plasma is approximated as a high temperature region. The flow characteristics without the plasma actuation correspond to the experimental observation, indicating that the numerical method successfully resolves the shock-wave/Boundary-Layer interaction. With the plasma actuation, complete agreement between the experiment and calculation has not been obtained in the size of the shock-wave/Boundary-Layer interaction region. Nevertheless, as with the experiment, the calculation successfully demonstrates definite difference between the parallel and canted electrodes: the parallel electrode causes excess heating and increases the strength of the interaction, while the canted electrode leads to a reduction of the interaction strength, with a corresponding thinning of the Boundary Layer due to the momentum transfer. The counter flow created by the canted actuator plays an important role in the vortex generation, transferring momentum to the Boundary Layer and, consequently, mitigating the shock induced Boundary Layer Separation.This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numeri...

  • numerical study of Boundary Layer Separation control using magnetogasdynamic plasma actuators
    Physics of Fluids, 2009
    Co-Authors: Chiranjeev S. Kalra, Mikhail N Shneider, Richard B. Miles
    Abstract:

    In this study, an efficient, time dependent, two-dimensional Navier–Stokes numerical code for shockwave Boundary Layer interaction in air is developed. Nonthermal surface plasma actuation is evaluated for effective shockwave induced Boundary Layer Separation control within supersonic inlets. Specifically, high speed magnetogasdynamic plasma actuators are of interest. In these, localized ionization is produced close to the wall surface and then the flow is accelerated using strong magnetic fields. To replicate the experiments done at large Boundary Layer thickness, the code is divided into time independent and time dependent regimes to significantly reduce computation time. Computational results are in good agreement with experiments in terms of the flow structure as shown by Schlieren imaging, acetone planar laser scattering, and the static pressure profile on the test section wall.

  • Magnetically Driven Surface Discharges for Shock-Wave Induced Boundary-Layer Separation Control
    45th AIAA Aerospace Sciences Meeting and Exhibit, 2007
    Co-Authors: Chiranjeev S. Kalra, Sohail Zaidi, Bruce J. Alderman, Richard B. Miles
    Abstract:

    This study investigates the impact of a magnetically driven surface plasma column (“snowplow arc”) on shock induced Boundary Layer Separation. The surface plasma column appears as a transverse “arc” between two diverging electrodes which is driven by j x B forces so that it sweeps the gas near the surface either in the downstream direction or in the upstream direction. In the experimental setup, an oblique shockwave wave was generated using a ten degree wedge in a Mach 2.8 indraft tunnel. The shock wave impinged on the flat surface in close proximity to the plasma actuator. Experimental results revealed a coupling of the plasma column with the shock – Boundary Layer interaction region which resulted in a change in the location of the shock induced Boundary Layer Separation point. In case of the body force j x B acting upstream, the Separation point was seen to move upstream. In case of the downstream j x B body force, a very small coupling was observed and the Separation point appeared largely unaffected. Various reasons for the absence of an interaction in the downstream direction are discussed, particularly including the ratio of the scale of the plasma column to the Boundary thickness. A sapphire insert with embedded electrodes is under development to allow for a higher current which then may be more effective for the suppression of Boundary Layer Separation.

J. D. A. Walker - One of the best experts on this subject based on the ideXlab platform.

  • The onset of instability in unsteady Boundary-Layer Separation
    Journal of Fluid Mechanics, 1996
    Co-Authors: Kevin W. Cassel, Frank T. Smith, J. D. A. Walker
    Abstract:

    The process of unsteady two-dimensional Boundary-Layer Separation at high Reynolds number is considered. Solutions of the unsteady non-interactive Boundary-Layer equations are known to develop a generic Separation singularity in regions where the pressure gradient is prescribed and adverse. As the Boundary Layer starts to separate from the surface, however, the external pressure distribution is altered through viscous-inviscid interaction just prior to the formation of the Separation singularity; hitherto this has been referred to as the first interactive stage. A numerical solution of this stage is obtained here in Lagrangian coordinates. The solution is shown to exhibit a high-frequency inviscid instability resulting in an immediate finite-time breakdown of this stage. The presence of the instability is confirmed through a linear stability analysis. The implications for the theoretical description of unsteady Boundary-Layer Separation are discussed, and it is suggested that the onset of interaction may occur much sooner than previously thought.

  • Hypersonic Boundary-Layer Separation on a cold wall
    Journal of Fluid Mechanics, 1994
    Co-Authors: R. M. Kerimbekov, Anatoly I. Ruban, J. D. A. Walker
    Abstract:

    An asymptotic theory of laminar hypersonic Boundary-Layer Separation for large Reynolds number is described for situations when the surface temperature is small compared with the stagnation temperature of the inviscid external gas flow. The interactive Boundary-Layer structure near Separation is described by well-known triple-deck concepts but, in contrast to the usual situation, the displacement thickness associated with the viscous subLayer is too small to influence the external pressure distribution (to leading order) for sufficiently small wall temperature. The present interaction takes place between the main part of the Boundary Layer and the external flow and may be described as inviscid-inviscid

Kiyoshi Kinefuchi - One of the best experts on this subject based on the ideXlab platform.

  • numerical investigation of nanosecond pulsed plasma actuators for control of shock wave Boundary Layer Separation
    Physics of Fluids, 2018
    Co-Authors: Kiyoshi Kinefuchi, Andrey Starikovskiy, Richard B. Miles
    Abstract:

    This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numerical investigation is undertaken with a large eddy simulation and an energy deposition model for the plasma actuation, in which the dielectric barrier discharge produced plasma is approximated as a high temperature region. The flow characteristics without the plasma actuation correspond to the experimental observation, indicating that the numerical method successfully resolves the shock-wave/Boundary-Layer interaction. With the plasma actuation, complete agreement between the experiment and calculation has not been obtained in the size of the shock-wave/Boundary-Layer interaction region. Nevertheless, as with the experiment, the calculation successfully demonstrates definite difference between the parallel and canted electrodes: the parallel electrode causes excess heating and increases the strength of the interaction, while the canted electrode leads to a reduction of the interaction strength, with a corresponding thinning of the Boundary Layer due to the momentum transfer. The counter flow created by the canted actuator plays an important role in the vortex generation, transferring momentum to the Boundary Layer and, consequently, mitigating the shock induced Boundary Layer Separation.This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numeri...

  • Numerical investigation of nanosecond pulsed plasma actuators for control of shock-wave/Boundary-Layer Separation
    Physics of Fluids, 2018
    Co-Authors: Kiyoshi Kinefuchi, Andrey Starikovskiy, Richard B. Miles
    Abstract:

    This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numerical investigation is undertaken with a large eddy simulation and an energy deposition model for the plasma actuation, in which the dielectric barrier discharge produced plasma is approximated as a high temperature region. The flow characteristics without the plasma actuation correspond to the experimental observation, indicating that the numerical method successfully resolves the shock-wave/Boundary-Layer interaction. With the plasma actuation, complete agreement between the experiment and calculation has not been obtained in the size of the shock-wave/Boundary-Layer interaction region. Nevertheless, as with the experiment, the calculation successfully demonstrates definite difference between the parallel and canted electrodes: the parallel electrode causes excess heating and increases the strength of the interaction, while the canted electrode leads to a reduction of the interaction strength, with a corresponding thinning of the Boundary Layer due to the momentum transfer. The counter flow created by the canted actuator plays an important role in the vortex generation, transferring momentum to the Boundary Layer and, consequently, mitigating the shock induced Boundary Layer Separation.This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numeri...

Chiranjeev S. Kalra - One of the best experts on this subject based on the ideXlab platform.

  • numerical study of Boundary Layer Separation control using magnetogasdynamic plasma actuators
    Physics of Fluids, 2009
    Co-Authors: Chiranjeev S. Kalra, Mikhail N Shneider, Richard B. Miles
    Abstract:

    In this study, an efficient, time dependent, two-dimensional Navier–Stokes numerical code for shockwave Boundary Layer interaction in air is developed. Nonthermal surface plasma actuation is evaluated for effective shockwave induced Boundary Layer Separation control within supersonic inlets. Specifically, high speed magnetogasdynamic plasma actuators are of interest. In these, localized ionization is produced close to the wall surface and then the flow is accelerated using strong magnetic fields. To replicate the experiments done at large Boundary Layer thickness, the code is divided into time independent and time dependent regimes to significantly reduce computation time. Computational results are in good agreement with experiments in terms of the flow structure as shown by Schlieren imaging, acetone planar laser scattering, and the static pressure profile on the test section wall.

  • Magnetically Driven Surface Discharges for Shock-Wave Induced Boundary-Layer Separation Control
    45th AIAA Aerospace Sciences Meeting and Exhibit, 2007
    Co-Authors: Chiranjeev S. Kalra, Sohail Zaidi, Bruce J. Alderman, Richard B. Miles
    Abstract:

    This study investigates the impact of a magnetically driven surface plasma column (“snowplow arc”) on shock induced Boundary Layer Separation. The surface plasma column appears as a transverse “arc” between two diverging electrodes which is driven by j x B forces so that it sweeps the gas near the surface either in the downstream direction or in the upstream direction. In the experimental setup, an oblique shockwave wave was generated using a ten degree wedge in a Mach 2.8 indraft tunnel. The shock wave impinged on the flat surface in close proximity to the plasma actuator. Experimental results revealed a coupling of the plasma column with the shock – Boundary Layer interaction region which resulted in a change in the location of the shock induced Boundary Layer Separation point. In case of the body force j x B acting upstream, the Separation point was seen to move upstream. In case of the downstream j x B body force, a very small coupling was observed and the Separation point appeared largely unaffected. Various reasons for the absence of an interaction in the downstream direction are discussed, particularly including the ratio of the scale of the plasma column to the Boundary thickness. A sapphire insert with embedded electrodes is under development to allow for a higher current which then may be more effective for the suppression of Boundary Layer Separation.

Andrey Starikovskiy - One of the best experts on this subject based on the ideXlab platform.

  • numerical investigation of nanosecond pulsed plasma actuators for control of shock wave Boundary Layer Separation
    Physics of Fluids, 2018
    Co-Authors: Kiyoshi Kinefuchi, Andrey Starikovskiy, Richard B. Miles
    Abstract:

    This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numerical investigation is undertaken with a large eddy simulation and an energy deposition model for the plasma actuation, in which the dielectric barrier discharge produced plasma is approximated as a high temperature region. The flow characteristics without the plasma actuation correspond to the experimental observation, indicating that the numerical method successfully resolves the shock-wave/Boundary-Layer interaction. With the plasma actuation, complete agreement between the experiment and calculation has not been obtained in the size of the shock-wave/Boundary-Layer interaction region. Nevertheless, as with the experiment, the calculation successfully demonstrates definite difference between the parallel and canted electrodes: the parallel electrode causes excess heating and increases the strength of the interaction, while the canted electrode leads to a reduction of the interaction strength, with a corresponding thinning of the Boundary Layer due to the momentum transfer. The counter flow created by the canted actuator plays an important role in the vortex generation, transferring momentum to the Boundary Layer and, consequently, mitigating the shock induced Boundary Layer Separation.This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numeri...

  • Numerical investigation of nanosecond pulsed plasma actuators for control of shock-wave/Boundary-Layer Separation
    Physics of Fluids, 2018
    Co-Authors: Kiyoshi Kinefuchi, Andrey Starikovskiy, Richard B. Miles
    Abstract:

    This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numerical investigation is undertaken with a large eddy simulation and an energy deposition model for the plasma actuation, in which the dielectric barrier discharge produced plasma is approximated as a high temperature region. The flow characteristics without the plasma actuation correspond to the experimental observation, indicating that the numerical method successfully resolves the shock-wave/Boundary-Layer interaction. With the plasma actuation, complete agreement between the experiment and calculation has not been obtained in the size of the shock-wave/Boundary-Layer interaction region. Nevertheless, as with the experiment, the calculation successfully demonstrates definite difference between the parallel and canted electrodes: the parallel electrode causes excess heating and increases the strength of the interaction, while the canted electrode leads to a reduction of the interaction strength, with a corresponding thinning of the Boundary Layer due to the momentum transfer. The counter flow created by the canted actuator plays an important role in the vortex generation, transferring momentum to the Boundary Layer and, consequently, mitigating the shock induced Boundary Layer Separation.This study numerically explores the flow physics associated with nanosecond pulsed plasma actuators that are designed to control shock-wave induced Boundary-Layer Separation in a Mach 2.8 supersonic flow. By using two dielectric barrier surface discharge actuator configurations, parallel and canted with respect to the flow velocity vector, a previous experiment suggested that the actuator worked in two ways to influence the interaction: Boundary Layer heating and vorticity production. The heating effect was enhanced with the parallel electrode and made the Boundary-Layer Separation stronger, while the canted electrode produced vorticity and suppressed the Boundary-Layer Separation due to the momentum transfer from the core flow. Because the detailed physical processes are still unclear, in this paper a numeri...