Generalization of the Total Current–Voltage Characteristics for Transferred Arc Plasma Torch With Steam and Air Plasmas Based on the Analytical Anisotropic Model

Abstract

Total current–voltage characteristics (CVCs) of a transferred arc plasma torch were determined for the case of oxidative plasma type, steam and air, by the application of the anisotropic analytical model to dc electric arc. The model takes into account the arc radiation reabsorption in the approximation of radiant thermal conductivity and is based on the power function approximation of temperature dependence on plasma electrical conductivity with different exponents along the longitudinal and transversal coordinates. The experimental data generalization for a 50-kW plasma torch was obtained in a simple form of dimensionless expression with a high statistically acceptable level. The electric resistance of arc as a generalized function ${\pi _{\rm dep}}$ is mainly affected by convection number of the energy transfer ${\pi _{\rm conv}}$ . This generalized characteristic can be used with subsequent application in the design of steam- and air-transferred arc plasma torches at a wide range of dimensionless numbers: ${\pi _{\rm dep}}$ between 90 and 932, ${\pi _{\rm conv}}$ from $5.16 \times {10^{ - 5}}$ to $1.76 \times {10^{ - 3}}$ , and the Reynolds number from 526 to 2212.