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Vodní a hybridní plazmatrony s plynovou a vodní stabilizací
Hrabovský, Milan
Plasma torches with water-stabilized arc (Gerdien arc) are utilized in plasma processing for specific applications. In water-stabilized torches an oxygen-hydrogen plasma jet is produced. The torches are characterized by very low mass flow rates and high power. Plasma enthalpy is thus several times higher than enthalpy of plasmas generated in gas-stabilized torches. High enthalpy is accompanied by very low plasma density. Also other plasma parameters substantially differ from the ones in gas torches. New type of plasma torch with combined stabilization of an electric arc by water vortex and gas flow was investigated. This hybrid water/gas stabilization offers possibility of adjustment of plasma jet parameters in a wide range from high enthalpy, low density plasmas typical for liquid stabilized torches to lower enthalpy, higher density plasmas generated in gas stabilized torches.
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Mapování teplotního a rychlostního pole ve volném proudu horkého plynu
Gregor, Jan ; Jakubová, I. ; Mendl, T. ; Šenk, J.
In the paper the measurements on hot gas mixture free jet are analyzed. The main interest is oriented on the analysis of the distribution of the individual species in the jet based on the vector form of the continuity and momentum equation. In the continuity equation the diffusion member is involved. To simplify the problem, the temperature and velocity fields are approximated by suitable functions. The calculation process is applied on the jet generated by a hybrid water stabilized plasma torch with argon added into the chamber of a plasma heater.
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Modelování směšování plazmatu vodní páry s parní atmosférou v tepelném plazmovém reaktoru
Hirka, Ivan ; Jeništa, Jiří ; Hrabovský, Milan
Two-dimensional CFD modelling of mixing of steam plasma jet with steam atmosphere in thermal plasma reactor has been carried out. Temperature of steam plasma is approximately 15 000 K and temperature of steam atmosphere is 400 K. Standard, RNG, and realizable k-e models were used for all simulations. Steam plasma and steam atmospheric properties were generated by the ADEP code. Results for temperature, velocity and density distributions are discussed and presented as images obtained from the FLUENT code, for currently used reactor geometry setup and plasma flow.
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Studium difuzního proudu na hranici oblouku pomocí elektrických sond
Chumak, Oleksiy ; Hrabovský, Milan ; Kavka, Tetyana ; Kopecký, Vladimír
Electric probes were used for investigation of an intermediate layer between the arc and anode surface in regions outside the main current channel. Distributions of a diffuse current and the potential were measured. Resistance and heating of the intermediate layer by diffuse current were evaluated.It was found that not only the value of diffuse current strongly depends on distance from the arc but also the shape of the distribution and the position of the maximum of the current change with the distance. These trends can be explained by expanding of the plasma jet. Evaluated equivalent intermediate layer resistance shows widening of the conductive region in a stream wise direction. Variation of resistivity of the intermediate layer is much higher than variation of the potential drop on the layer. That means that distributed current as well as Joule heating of the layer are generally controlled by distributed resistance.
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Studium expandujícího proudu termického plazmatu s využitím molekulových spekter
Mašláni, Alan ; Sember, Viktor
Thermal plasmas generated by plasma torches are well-known for their high temperatures and high enthalpies. Therefore optical emission spectroscopy is appropriate diagnostic method because of strong emission of radiation corresponding to the visible light. The decay of excited atoms, ions and molecules causes emission of the light at characteristic wavelengths. Except spectral lines of atoms and ions, also some molecular bands can be seen in the spectra of the plasma jet. Especially expanding thermal plasma jet operated under low pressure conditions offers possibility of observing molecular transitions. Pressure lower than atmospheric may cause the presence of supersonic flow and departures from thermodynamic equilibrium. Spectra of OH radical have been investigated using computer code LIFBASE, which contains a lot of data regarding spectra of diatomic molecules. Radial profiles of rotational and vibrational temperatures have been found in several regions of the jet.
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