The vortex gas injection into plasma torch is considered as a method for reducing electrodes erosion. In order to investigate the effects of vortex gas injection on plasma structure, as well as the effect of gas viscosity on the rate of rotation, a threedimensional nonequilibrium and time-dependent non-transferred DC plasma torch model has been simulated. Viewing the general characteristics of the plasma shows that the model works well. The results have shown that if the components of the inlet gas velocity are not properly selected, it is possible that the rotary effects of the gas are greatly depleted even before the gas reaches the cathode tip and plasma formation. In this case, only the change in the axial component of the gas causes changes in the structure of the plasma. Vortex reduction is also observed during the movement of cold gases. It is observed that the change in viscosity of gas has significant effects on the rate of the vortex.

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