Heat transfer around a spherical particle levitated in argon plasma jet

Institut de Science et de Génie des Matériaux et Procédés (UPR 8521), B.P.5, 66125 Font-Romeu, France

Corresponding author: snabre@imp-odeillo.fr

Received: 6 February 1998
Revised: 25 June 1998
Accepted: 28 June 1998
Published online: 15 September 1998

Abstract

This paper concerns momentum and heat transfer to a nonevaporating oxidized steel spherical particle (diameter 6.5 mm − 8 mm) levitated at high Reynolds number in argon turbulent plasma jet flowing into cold air. The rapid rotation of the particle in the plasma flow ensures the stability of the levitation phenomenon over a wide range of plasma torch parameters. We use a dimensional analysis to describe the momentum transfer and the equilibrium levitation height data. The convective heat transfer coefficient was further estimated from gas and particle equilibrium temperature at the front stagnation point or from the analysis of the transient temperature signal for a particle abruptly immersed and levitated in the plasma jet. Particle rotation is shown to determine the heat transfer rate in a nonuniform plasma flow.