Numerical analysis of flow characteristics of an atmospheric plasma torch

Abstract

The atmospheric plasma is regarded as an effective method for surface treatments because it can reduce the period of process and does not need expensive vacuum apparatus. The performance of non-transferred plasma torches is significantly depended on jet flow characteristics out of the nozzle. In order to produce the high performance of a torch, the maximum discharge velocity near an annular gap in the torch should be maintained. Also, the compulsory swirl is being produced to gain the shape that can concentrate the plasma at the center of gas flow. Numerical analysis of two different mathematical models used for simulating plasma characteristics inside an atmospheric plasma torch is carried out. A qualitative comparison is made in this study to test the accuracy of these two different model predictions of an atmospheric plasma torch. Numerical investigations are carried out to examine the influence of different model assumptions on the resulting plasma characteristics. Significant variations in the results in terms of the plasma velocity and temperature are observed. These variations will influence the subsequent particle dynamics in the thermal spraying process. The uniformity of plasma distribution is investigated. For analyzing the swirl effects in the plenum chamber and the flow distribution, FVM (finite volume method) and a SIMPLE algorithm are used for solving the governing equations.