Analysis of flow and heat-transfer characteristics of DC-RF hybrid plasma based on turbulence model

Abstract

BackgroundDirect-current radiofrequency (DC-RF) hybrid plasma has broad application prospects in the field of nuclear ultrafine powder material preparation owing to its characteristics of high temperature and high chemical activity.PurposeThis study aims to explore the flow and heat-transfer characteristics of DC-RF hybrid plasma, so as to provide references for the design and stable operation of the plasma generator device.MethodsFirst of all, the hybrid plasma generator was assumed to be a two-dimensional axisymmetric model, and the device was filled with pure argon plasma in a local thermodynamic equilibrium (LTE), steady, and turbulent flow state. Then, the ANSYS FLUENT software was employed to establish a two-dimensional model for the DC-RF hybrid plasma torch structure, and the spatial distributions of the temperature and flow field in DC-RF hybrid plasma torch were simulated using the k-ε turbulence model with SIMPLE algorithm based on velocity and pressure coupling solver. Finally, the effects of changes in the operating parameters were analyzed based on these results.Results & ConclusionsThe simulation results indicate that increases in the DC arc current, reaction gas flow rate, and cooling gas flow rate can reduce backflow effects at the entrance of hybrid plasma torch. The temperature and area of the plasma arc near the RF coil increase with the RF coil current. However, an excessive current and gas flow rate may adversely affect the operation of the device. Various requirements of material handling processes on the premise of stable operation of the device can be satisfied by adjusting working parameters for the control of the hybrid plasma flow field profiles.

Keywords

• dc-rf hybrid plasma
• turbulence model
• temperature
• flow field
• numerical simulation