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G Gerbeth - One of the best experts on this subject based on the ideXlab platform.

  • the flow structure of a bubble driven liquid metal jet in a horizontal magnetic field
    Journal of Fluid Mechanics, 2007
    Co-Authors: C Zhang, S Eckert, G Gerbeth
    Abstract:

    Static magnetic fields are known to be suitable for damping mean flow and turbulent motion in an electrically conducting liquid. In this paper, an experimental study is presented considering the influence of a horizontal magnetic field on a bubble-driven flow of a liquid metal. The investigation is focused on the liquid circulation inside a liquid metal column driven by a central jet produced by gas injection. The fluid vessel has a circular cross-section and electrically insulating walls. Low gas flow rates were applied, resulting in a plume of separated bubbles rising inside a spot around the cylinder axis. This axisymmetric configuration is exposed to a horizontal magnetic field. We present detailed experimental data describing the spatial as well as the temporal structure of the Velocity field. Measurements of the vertical and the Radial Velocity Component, respectively, were performed using the ultrasound Doppler velocimetry (UDV), allowing for the first time a complete mapping of the liquid Velocity distribution for a bubble-driven liquid metal flow. The magnetic field considerably modified the global and local properties of the flow field compared to an ordinary bubble plume. In the parameter range considered here we did not find a prior flow suppression, but, in fact, a restructuring of the convective motion. The original axisymmetric flow field became anisotropic with respect to the direction of the magnetic field lines. An upwards flow dominated in a plane parallel to the magnetic field, whereas the recirculating motion was enforced in the orthogonal plane. Contrary to usual expectations, the application of a moderate magnetic field (100 < Ha < 400,1 ≤ N ≤ 10) destabilizes the global flow and gives rise to transient, oscillating flow patterns with predominant frequencies.

C Zhang - One of the best experts on this subject based on the ideXlab platform.

  • the flow structure of a bubble driven liquid metal jet in a horizontal magnetic field
    Journal of Fluid Mechanics, 2007
    Co-Authors: C Zhang, S Eckert, G Gerbeth
    Abstract:

    Static magnetic fields are known to be suitable for damping mean flow and turbulent motion in an electrically conducting liquid. In this paper, an experimental study is presented considering the influence of a horizontal magnetic field on a bubble-driven flow of a liquid metal. The investigation is focused on the liquid circulation inside a liquid metal column driven by a central jet produced by gas injection. The fluid vessel has a circular cross-section and electrically insulating walls. Low gas flow rates were applied, resulting in a plume of separated bubbles rising inside a spot around the cylinder axis. This axisymmetric configuration is exposed to a horizontal magnetic field. We present detailed experimental data describing the spatial as well as the temporal structure of the Velocity field. Measurements of the vertical and the Radial Velocity Component, respectively, were performed using the ultrasound Doppler velocimetry (UDV), allowing for the first time a complete mapping of the liquid Velocity distribution for a bubble-driven liquid metal flow. The magnetic field considerably modified the global and local properties of the flow field compared to an ordinary bubble plume. In the parameter range considered here we did not find a prior flow suppression, but, in fact, a restructuring of the convective motion. The original axisymmetric flow field became anisotropic with respect to the direction of the magnetic field lines. An upwards flow dominated in a plane parallel to the magnetic field, whereas the recirculating motion was enforced in the orthogonal plane. Contrary to usual expectations, the application of a moderate magnetic field (100 < Ha < 400,1 ≤ N ≤ 10) destabilizes the global flow and gives rise to transient, oscillating flow patterns with predominant frequencies.

Pyckin, Yu. A. - One of the best experts on this subject based on the ideXlab platform.

  • Effect of a gas-vortex stabilization method on the kinematic properties of the jet in metal-cutting plasmatrons
    Institute of Physics Publishing, 2019
    Co-Authors: Anakhov S., Matushkin A., Pyckin, Yu. A.
    Abstract:

    Various methods of gas-vortex stabilization in plasma cutting torches are investigated. The results of the study demonstrate the dependence of the angle of gas injection into the nozzle on the kinematic and kinetic characteristics of plasma jet and, consequently, on the cutting parameters. Increased Radial Velocity Component at the swirler output provides better uniformity of the Velocity distribution and kinetic properties of the jet in the affected zone of a cut metal. As a conclusion, it is recommended to use the suggested narrow-jet-plasma technology for cutting thin sheet metals. © 2019 IOP Publishing Ltd

  • Effect of a gas-vortex stabilization method on the kinematic properties of the jet in metal-cutting plasmatrons
    'IOP Publishing', 2019
    Co-Authors: Anakhov S., Matushkin A., Pyckin, Yu. A.
    Abstract:

    Various methods of gas-vortex stabilization in plasma cutting torches are investigated. The results of the study demonstrate the dependence of the angle of gas injection into the nozzle on the kinematic and kinetic characteristics of plasma jet and, consequently, on the cutting parameters. Increased Radial Velocity Component at the swirler output provides better uniformity of the Velocity distribution and kinetic properties of the jet in the affected zone of a cut metal. As a conclusion, it is recommended to use the suggested narrow-jet-plasma technology for cutting thin sheet metals. © 2019 IOP Publishing Ltd.Ministry of Science and Higher Education of the Russian Federation: 13.10317.2018/11.12The work was executed under the support of state assignment of the Ministry of Science and Higher Education of the Russian Federation No. 13.10317.2018/11.12

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

  • the flow structure of a bubble driven liquid metal jet in a horizontal magnetic field
    Journal of Fluid Mechanics, 2007
    Co-Authors: C Zhang, S Eckert, G Gerbeth
    Abstract:

    Static magnetic fields are known to be suitable for damping mean flow and turbulent motion in an electrically conducting liquid. In this paper, an experimental study is presented considering the influence of a horizontal magnetic field on a bubble-driven flow of a liquid metal. The investigation is focused on the liquid circulation inside a liquid metal column driven by a central jet produced by gas injection. The fluid vessel has a circular cross-section and electrically insulating walls. Low gas flow rates were applied, resulting in a plume of separated bubbles rising inside a spot around the cylinder axis. This axisymmetric configuration is exposed to a horizontal magnetic field. We present detailed experimental data describing the spatial as well as the temporal structure of the Velocity field. Measurements of the vertical and the Radial Velocity Component, respectively, were performed using the ultrasound Doppler velocimetry (UDV), allowing for the first time a complete mapping of the liquid Velocity distribution for a bubble-driven liquid metal flow. The magnetic field considerably modified the global and local properties of the flow field compared to an ordinary bubble plume. In the parameter range considered here we did not find a prior flow suppression, but, in fact, a restructuring of the convective motion. The original axisymmetric flow field became anisotropic with respect to the direction of the magnetic field lines. An upwards flow dominated in a plane parallel to the magnetic field, whereas the recirculating motion was enforced in the orthogonal plane. Contrary to usual expectations, the application of a moderate magnetic field (100 < Ha < 400,1 ≤ N ≤ 10) destabilizes the global flow and gives rise to transient, oscillating flow patterns with predominant frequencies.

N. F. Ness - One of the best experts on this subject based on the ideXlab platform.

  • heliosheath magnetic fields between 104 and 113 au in a region of declining speeds and a stagnation region
    The Astrophysical Journal, 2012
    Co-Authors: L. F. Burlaga, N. F. Ness
    Abstract:

    We examine the relationships between the magnetic field and the Radial Velocity Component VR observed in the heliosheath by instruments on Voyager 1 (V1). No increase in the magnetic field strength B was observed in a region where VR decreased linearly from 70 km s–1 to 0 km s–1 as plasma moved outward past V1. An unusually broad transition from positive to negative polarity was observed during a ≈26 day interval when the heliospheric current sheet (HCS) moved below the latitude of V1 and the speed of V1 was comparable to the Radial speed of the heliosheath flow. When V1 moved through a region where VR ≈ 0 (the "stagnation region"), B increased linearly with time by a factor of two, and the average of B was 0.14 nT. Nothing comparable to this was observed previously. The magnetic polarity was negative throughout the stagnation region for ≈580 days until 2011 DOY 235, indicating that the HCS was below the latitude of V1. The average passage times of the magnetic holes and proton boundary layers were the same during 2009 and 2011, because the plasma moved past V1 during 2009 at the same speed that V1 moved through the stagnation region during 2011. The microscale fluctuations of B in the stagnation region during 2011 are qualitatively the same as those observed in the heliosheath during 2009. These results suggest that the stagnation region is a part of the heliosheath, rather than a "transition region" associated with the heliopause.