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Influence of DC arc jets on flow fields analyzed by an integrated numerical model for a DC–RF hybrid plasma

Cited 6 time in Web of Science Cited 6 time in Scopus
Authors
Seo, Jun Ho; Park, Jin Myung; Hong, Sang Hee
Issue Date
2008-03-11
Publisher
Institute of Physics
Citation
Plasma Sources Science and Technology 17 025011
Keywords
dc-rf hybrid plasmadc arc jet effectsthermal plasma flow fieldsintegrated numerical model
Abstract
The influence of DC arc jets on the flow fields in a hybrid plasma torch is numerically analyzed by an integrated direct current–radio frequency (DC–RF) plasma model based on magneto-hydrodynamic formulations. The calculated results reveal that the increase in DC arc gas flow rate raises the axial flow velocity along the central column of the DC–RF hybrid plasma together with the enhanced backflow streams in the peripheral wall region. The temperature profiles on the torch exit plane are little affected due to the reheating process of the central column by the combined RF plasma. Accordingly, the exit enthalpy emitted from the DC–RF hybrid torch can be concentrated to the central column of the plasma and controlled by adjusting the DC arc gas flow rate. The swirl in the sheath gas flow turns out to have the opposite effect on the DC arc gas flow rate. The swirling motion of the sheath gas can reduce the back flows near the induction tube wall as well as the axial velocities in the central column of the plasma. Accordingly, the swirl in the sheath gas flow can be used for the functional operation of the DC–RF hybrid plasma along with the DC arc gas flow rate to suppress the back flows at the wall region and to reduce the excessive interactions between the DC arc jet and the ambient RF plasmas. The effects of DC input current on the flow fields of hybrid plasma are similar to those of the DC arc gas flow rate, but the axial velocities for the higher current relatively quickly decay along the centerline. This is in contrast to the increase in the axial velocity remaining in proportion to the increase in the DC arc gas flow rate all the way up to the exit of the DC–RF hybrid plasma. Accordingly, the present integrated numerical analysis suggests that the hybrid plasma field profiles and the entrainment of ambient air from the torch exit are controllable by adjusting the DC arc gas flow rate, the DC input current and swirl in the sheath gas flow taking advantage of their opposite and complementary effects on the flow fields of the hybrid plasma.
ISSN
0963-0252
Language
English
URI
https://hdl.handle.net/10371/69101
DOI
https://doi.org/10.1088/0963-0252/17/2/025011
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Energy Systems Engineering (에너지시스템공학부)Nuclear Engineering (원자핵공학전공)Journal Papers (저널논문_원자핵공학과)
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