Zhainakov A.  

About selecting the computational domain when critical modes of plasma arc flow.

About selecting the computational domain when critical modes of plasma arc flow. A. Zhainakov, J.O. Usenkanov* Kyrgyz State Technical University named after i. Razzakova, Institute of mining and mining technology name akad. U. Асаналиева. *e-mail address: juma_21@mail.ru Mathematical modeling of physical processes in arc plasma flows devices is conducted on the basis of a system of Magnetohydrodynamic (MHD) equations, which include the Navier-Stokes equations, Maxwell and energy equations. The system is supplemented by State equation coefficients transfer Wednesday and the rele-vant boundary conditions. Selection of computational domain is usually determined by the geometry of the technical device, discharge or other such considerations. On the borders of the settlement area, on the basis of reasonable physical assumptions are justified and are determined by the boundary conditions. In the calculations the calculation and raised them boundary conditions can be verified and adjusted. As a result of the carried out researches it has been established that there were currents of plasma arc flow modes for which the border settlement area should be checked with insignificant alterations of such external parameters of electric arc like electricity or gas consumption. As an example, threads are considered arc plasma welding plazmatronom generated in Wednesday carbon dioxide or argon. As the anode is selected polubeskonečnaâ plate on which the natekaet flowing from the nozzle flow plazmatrona channel arc plasma and spreads further in the radial direction. The first. During close to turbulent plasma flow regime (let's call them critical), defining boundary conditions for radial velocity and temperature distributions at the cut channel plazmatrona have to take into account the geometry and dimensions, as well as plazmatrona channel devices. Otherwise, depending on boundary conditions, you can receive a variety of currents. In fact, this means that the inclusion in the settlement area of the entire turbine site, which includes channel nozzles plazmatrona and a cooled cathode. Selection of borders and conditions on them in this area is a separate task. The initial tasks of small orifice gas costs and a wide range of strength of electric current, radial velocity and temperature distribution at the nozzle correctly enough channel cutoff are put out of joint solution of the equations of motion of Hagen-poiseuille and Èlenbaasa-Geller. The second. Setting boundary conditions for the temperature at the surface of the anode is often determined by the analysis of experimental data. Speed on flat wall is equal to zero. Critical flow modes determining influence in this area become radial dimensions of anode and radial dimensions anode spots. As a result, there is a need for: concretization of the geometry and size of the anode; inclusion in the calculation of the anode site, taking into account the processes in near the surface of the anode and the anode. Studies of plasma arc welding genertruemoj flow plazmatronom found for achieving tangible results in the area of calculation must include not only the area burning electric arc, but also associated with it, which include the cathode node and plazmatrona nozzle, tube site. When the mating task with a selection of computational domain boundaries and boundary conditions on them practically no problems arise. References 1 Jainakov A., Usenkanov J. О., Jumaliev Т.R., Kydyraliev S.К. (Plasma jets in the development of new materials technology. Proc. of the Inter. Workshop, Frunze, 1990.) Study of electric arc plasma flow in transition region from laminar to turbulent current. // 2 Usenkanov, j. o., Asanaliev t.r., Djumaliev M.k. plasma streams flow Modes in compressed arc//low-temperature plasma Generators. Tez. report. T. 2 Novosibirsk, 1989. 3 Zhaynakov A., Usenkanov J. A. Plasma flows generated by the welding arc. Ilim, Bishkek, 2000. – 114p.