Metal Stream Research Articles

Behavior of liquid metal stream in a transverse magnetic field

This is a theoretical study of the effect of a transverse magnetic field on the flow characteristics of a two-dimensional laminar submerged jet stream of an electrically conducting, viscous, incompressible fluid. The analysis may be applicable to liquid metal jet streams for two limiting cases: (i) small magnetic field or (ii) slow motion. In either limiting case, an increase in the intensity of the magnetic field is shown to enhance the extent of velocity decay in the downstream direction.

Electric field dependence of GaAs Schottky barriers

The bias dependence of the photoelectric barrier energy of n-GaAsAl diodes has been measured. The devices were fabricated by cleavage of the GaAs in an evaporating stream of metal in a vacuum of 10 −8 torr. The barrier energies at various bias levels were determined by extrapolation of the photoresponse vs. photon energy plots. The electric field dependence of the photoresponse was also measured at constant photon energy. The calculated change in barrier energy from the latter method was then compared with the changes in extrapolated values of barrier energy. A small systematic disagreement was observed and attributed to the effects of collection efficiency in the GaAs. The field dependence of Schottky barriers on 5×10 16 GaAs was found to be in good agreement with that expected from the exponential charge distribution associated with the surface states which determine the barrier energy.

Mechanism of disintegration of molten metal streams by a gas jet

Mechanism of disintegration of molten metal streams by a gas jet

The Effect of Longitudinal Heat Conduction on Periodic-Flow Heat Exchanger Performance

A numerical finite-difference method of calculating the effectiveness for the periodic-flow type heat exchanger accounting for the effect of longitudinal heat conduction in the direction of fluid flow is presented. The method considers the metal stream in crossflow with each of the gas streams as two separate but dependent heat exchangers. To accommodate the large number of divisions necessary for accuracy and extrapolation to zero element area, use was made of a general purpose digital computer. The values of the effectiveness thus obtained are good to four significant figures while those values for the conduction effect are good to three significant figures. The exchanger effectiveness and conduction effect have been evaluated over the following range of dimensionless parameters. 1.0⩾Cmin/Cmax⩾0.901.0⩽Cr/Cmin⩽∞1.0⩽NTU0⩽1001.0⩾(hA)*⩾0.251.0⩾As*⩾0.250.01⩽λ⩽0.32

Graphite-containing refractories for ingot stools for top-pouring killed steel

Graphite-containing inserts made by the semi-dry method have an exact shape and size, exhibit high thermal conductivity and spalling resistance, and are resistant to the erosive and corrosive effect of a stream of liquid metal and to the oxidizing effect of high temperatures. The inserts can be used for multiple ingot casting in two molds, on condition the stream of liquid steel is kept central. The use of graphite-containing inserts manufactured by the technique developed by the authors does not affect the quality of the metal.

Heat-transfer in a tube to sodium-potassium alloy and to mercury

The existing experimental data on heat transfer to liquid metals often do not agree with each other, nor with theoretical values. The reasons for the discrepancies have so far not been clear. From the present work we can draw the conclusion that the main reason for the discrepancies is the thermal resistance that exists at the boundary between the heat-transfer surface and the liquid metal. We have come to this conclusion after measuring the heat-transfer coefficient to liquid metal by two methods: measuring the temperature distribution in the stream of liquid and measuring the temperature of the wall. The temperature distribution in the stream agreed with the distribution calculated from Lyon's equation. It was found that contamination of the sodium-potassium alloy by oxygen leads to a decrease of the heat-transfer coefficient. The results of experiments carried out in the absence of contact thermal resistance at the boundary between the wall and the liquid metal are in agreement with the results of Isakoff and Drew, and also with those of Brown, Amstead, and Short. The present paper contains a description of the experimental apparatus and of the tube section and thermocouple with which the temperature distribution in the stream of liquid metal was measured.

Increasing wear resistance of stoppers for 140-ton steel-casting ladles

Among the principal reasons for partial or substantial leaking of the metal stream are the following: burning away of the stopper, breaking off of the spherical part of the head, wear and tear of the head and sleeve bricks and opening up of the seams through deformation of the rod.

Heat Transfer in Pipes to a Sodium-Potassium Alloy and to Mercury

Experimental data on heat transfer to liquid metals are often conflicting and do not accord with theoretical results. The reasons for these discrepancies have not been clear. The present work shows that the main reason for the disagreement is the thermal resistance between the heated surface and the liquid metal. This conclusion is reached from calculations of the heat transfer coefficient by two methods: from measurements of the temperature distribution in the moving liquid and from measurements of the wall temperature. The former agrees with the distribution calculated from Lyon's equation. It has been found that the presence of oxygen in a sodium-potassium alloy reduces the heat transfer coefficient. The results of experiments with no contact thermal resistance agree with those of Isakoff and Drew and of Brownet al.A description is also given of the experimental apparatus, the test section, and a thermocouple whereby the temperature distribution in a stream of liquid metal can be measured.

Oxygen in liquid open-hearth steel—Oxidation during tapping and ladle filling

A mass of circumstantial evidence is presented to indicate that the main source of alloy losses in open-hearth tapping is oxidation by air, with the steel apparently reacting with an amount of oxygen equivalent to about 30 times its own volume of air. The effect is erratic from heat to heat, depending largely on turbulence and distance of free fall of the stream of liquid metal.

Societies and Academies

Societies and Academies