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Progress in Plasma Processing of Materials, 1997

ISBN:
1-56700-093-2 (Print)

MODELLING OF THE INFLUENCE OF IRON AND ALUMINA PARTICLES ON A DC PLASMA TORCH

J. M. Bauchire
GREMI, UMR 6606, University of Orleans, France

J. J. Gonzalez
Laboratoire Plasma et Conversion d'Energie, UMR UPS-INP-CNRS5213, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse cedex 9, France

Pierre Proulx
Chemical Engineering department, University of Sherbrooke

Abstract

A mathematical 2D representation is developed describing the temperature and the velocity profiles in a DC plasma torch and in the resulting plume. This model was previously described by Bauchire et al (1). It is based on the resolution of conservation equations using the SIMPLE method after Patankar (2). We present in this study the influence of the injection of iron and alumina particles on the characteristics of the plasma (temperature profiles) and the particle concentration fields obtained for different particle sizes and mass flow rates. For the two types of powder (iron and alumina) we compare the distribution of the powder on the plasma and the total absorbed power. The particles are injected in the jet at the exit of the torch. In order to take into account the effect of the particles on the plasma jet flow and temperature, we use the PSI-Cell technique, which has been developed by Crowe et al (3) and applied to plasma jets and plasma torches by Proulx et al (4).
The results show that the particle trajectories depend to a large extent on the particle injection conditions into the plasma jet, we can observe for example a complete evaporation of the particles in the first few centimeters when the velocity is low. This critical point was particularly studied in order to improve the control of the trajectories in the plasma spraying process.