要約

Numerical simulation modeling of laminar and turbulent plasma flows of an electric arc in plasma torches (plasmatrons) are examined in a wide range of working parameters (flow rates, currents, and channel diameters). The hydrodynamic and electric characteristics of plasmatrons in laminar and turbulent flows regimes and low-temperature argon plasma in plasma torches channels are studied. These calculations have confirmed our results previously obtained from analytical solutions: a. the generalized Poiseuille velocity profile for the viscous non-isothermal plasma flow in the plasma torch; b. the influence of the non-monotonous dependence of dynamic viscosity on plasma temperature on a flow structure and a friction coefficient; c. the dependencies of an axial gradient of pressure and the friction coefficient on electrical currents, on flow rates of the plasma forming gas and on internal diameters of the channel; d. the non-monotonous variation of viscosity on the cross section of plasmatron channels is generally the main reason for occurrence of two band points in the plasma velocity profile. Use of the specified technique has allowed to generalize results of experiments, precisely find the border of a turbulent regime flow in electric arcs, and to establish critical value of "effective" Reynolds number (Re_ef)_cr = 2000