Shroud gas effects on plasma characteristics of thermal plasma jets at atmospheric conditions
- Seoul National Univ. (Korea, Republic of). Dept. of Nuclear Engineering
High-enthalpy and high speed plasma flames ejected from nontransferred dc plasma torches have been widely used for material processings such as plasma spray coating and plasma synthesis. The plasma flow is produced by the arc-gas interactions between the cathode and anode inside the torch and expands as a jet through the nozzle into the air in the case of atmospheric conditions. The entrainment of surrounding air into the plasma flame, which reduces the quality of materials processed, is undesirable for the efficient material processings. This can be avoided by generating the plasma jets in the low pressure environment or by flowing the shroud gas around the jet flame. The torch operation with the shroud gas is simpler and more economic than the case of low pressure environment. In this work, shroud gas effects on the plasma flow at atmospheric conditions are investigated by a numerical analysis for finding the mole fraction of entrained air and the distributions of temperature and velocity components of plasma jets. The calculated results of temperature and velocity fields indicate that the plasma flame becomes longer and somewhat wider in the tail of the flame due to the less entrainment of air and the mixing of the swirling shroud gas with the plasma gas.
- OSTI ID:
- 419811
- Report Number(s):
- CONF-960634--
- Country of Publication:
- United States
- Language:
- English
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