  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.
