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The present paper details a comparison of experimental and computational results for the electrovortex flow of mercury in cylindrical and semi-cylindrical vessels, which is driven by the direct electrical current supplied over top and bottom non-submerged electrodes. The time-averaged velocity of liquid metal computed using the LES model of turbulence qualitatively and quantitatively agrees with the measured profiles of the axial velocity for a cylindrical experimental setup. For a semi-cylindrical setup which represents possible "cold" physical modelling of MHD devices, the observed flow patterns at the free surface and the computed flow patterns also agree qualitatively. [ABSTRACT FROM AUTHOR]

Controlling of electrovortex flows of liquid metal in a confined vessel is an essential feature of electrometallurgical technologies and aggregates, such as stirring, welding, electroslag remelting, electrical arc furnaces, etc. In the present study, the numerical model developed by the authors in previous studies has been improved to compute turbulent velocity and temperature fields for electrovortex flows of liquid metal in an experimental setup with the bifilar direct current supply over two fully submerged electrodes. Melt velocity and temperature fields were measured by applying a thermal-correlation method. The measured and computed results were compared. A good qualitative and quantitative agreement between the experimentally obtained data and the numerical computation results for the velocity field in several setup zones was found. [ABSTRACT FROM AUTHOR]

Electrovortex flow of liquid metal in a vessel relates to melt stirring in electrometallurgical processes and aggregates, such as welding, electroslag remelting, electrical arc furnaces and others. Maximum values of electromagnetic force and flow velocity develop in the zone between or under the electrodes, where sophisticated 3D flows are formed. In the paper, examples of electrovortex flows near two fully submerged electrodes with bifilar DC supply are discussed. The measured electrical potential and 3D self-magnetic field compared with results of numerical calculation and with a quasi 2D model of EM fields are discussed. Numerically computed 3D electrovortex flow patterns are presented for two regimes, i.e. (i) laminar and (ii) turbulent obtained with the LES approach. There is good qualitative and quantitative agreement between experimental data, analytical and numerical computation results, as well as with some previously published results. [ABSTRACT FROM AUTHOR]

Results of the numerical and experimental study of electrovortex flow patterns under an external magnetic field are presented. Experiments and calculations were performed in hemispherical geometry; the eutectic alloy (InGaSn) was used as a working liquid. Calculations were made with an external axial magnetic field up to 1 T and experiments with a magnetic field up to 0.02 T. It is found that the dependence of the flow intensity on the magnetic field magnitude is substantially non-monotonic. [ABSTRACT FROM AUTHOR]

Experimental and numerical results which summarize the influence of the external axial magnetic field on the pattern of flow which occurs when an electric current passes through a conducting medium between two hemispheres are presented. Calculations were made using different magnetohydrodynamic computational approaches and results compared. Methods presented in this paper involve electrodynamic approximation, non-inductive approximation and full coupled MHD problem. The discussed methods can be applied to calculate flow patterns in direct-current-arc furnaces and to other electrometallurgical problems. [ABSTRACT FROM AUTHOR]

With the help of numerical and experimental methods it was shown that a stationary external magnetic field, which causes an azimuthal swirl of axisymmetric electric flow, leads to the generation of intensive hydrodynamic self-oscillating processes in a current- carrying liquid metal. Calculations are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

Efficiency of application of electromagnetic actions for control of joint formation during electroslag welding is determined in many respects by application of external magnetic fields to welding zone and structural peculiarities of corresponding devices. The aim of present work lied in analysis of methods for generation of external magnetic fields during electroslag welding of butt joints and evaluation of their effect on weld pool melt. The main methods of generation of longitudinal and transverse magnetic fields in a welding gap are considered, and principal schemes of corresponding electromagnetic devices are given. It is shown that direction and intensity of electromagnetic force effecting the weld pool melt is determined first of all by spatial orientation of the external magnetic field in relation to object being welded, value of field magnetic induction and its frequency characteristics. Rationality of application of that or another scheme of application of magnetic field in the gap depends on welded joint parameters, and it should be considered separately for each individual case. Appropriateness of application of magnetic fields providing constant (cyclic) rearrangement of hydrodynamic structure of flows in the weld pool or creating melt vibration was indicated. In this case, usage of pulsed magnetic fields generated by discharges of capacitor batteries to electromagnet coil is perspective. Relevance of development of new schemes and devices for generation of magnetic fields and their power sources is shown. [ABSTRACT FROM AUTHOR]

Linear and non-linear stability analysis of the interface between a thin vapor film and a layer of liquid in the presence of a steady heat flux from a metal surface heated to a high temperature, to the vapor film and then from vapor to the subcooled liquid is investigated. The temperature dependence of saturation pressure is taken into account. Boundary conditions on the vapor-liquid interface that generalizes the known correlations on the free surface of liquid in the gravity field are derived. The thermal processes on the phase boundary lead to the generation of weakly decaying periodic surface waves of low amplitude and may cause small length waves (ripple), which are not capillary ones. Thermal processes on the phase interface are capable to provide the stability of a film of lights vapor under a layer of heavy liquid in the gravity field. The explosive instability may arise in the non-linear stage due to a weak variation of the film thickness or superheating of liquids. [ABSTRACT FROM AUTHOR]

Complex experimental study and numerical simulation of liquid metal flow and heat transfer in various configurations affected by longitudinal or transverse magnetic fields under conditions close to the tokamak reactor have been performed. A specific feature of the heat transfer under these conditions is the combined exposure of a strong magnetic field and thermogravitational forces, which manifests itself in previously unknown effects. Among these effects are the existence, in some modes, of MHD heat transfer areas of "degraded" heat transfer, the extremely uneven distribution of heat transfer coefficients along the perimeter of the tube and abnormally high temperature fluctuations near the wall. These phenomena including negative ones should be considered in the further designs. [ABSTRACT FROM AUTHOR]

Experimental investigation of liquid metal heat transfer in a horizontal heated tube in longitudinal and transverse magnetic fields (MF) was carried out. The experiment was approximated to conditions of heat exchanging channels of the TOKAMAK thermonuclear reactor. Heating was uniform along the length and, in the general case, non-uniform around the perimeter of the tube cross section. Temperature fields and velocity profiles, distributions of local and average heat-transfer coefficients, and statistic characteristics of turbulent fluctuations of temperature were measured. An appreciable effect of thermal gravity convection (TGC) on temperature fields and heat transfer in a horizontal tube was observed. Results of the effect of longitudinal and transverse magnetic fields differ greatly. [ABSTRACT FROM AUTHOR]