Velocity Of Liquid Metal Research Articles

Analysis of weld pool dynamic during stationary laser–MIG hybrid welding

A mathematical model was established to simulate the weld pool development and dynamic process in stationary laser–metal inert gas (MIG) hybrid welding. Surface tension and buoyancy were considered to calculate liquid metal flow pattern; moreover, typical phenomena of MIG welding such as filler droplets impinging weld pool, electromagnetic force in the weld pool, and typical phenomena of laser beam welding such as recoil pressure, inverse Bremsstrahlung absorption, and Fresnel absorption were all considered in the model. The laser beam and arc couple effect was introduced into this model by the plasma width during hybrid welding. Transient weld pool shape and complicated liquid metal velocity distribution from two kinds of weld pool to a unified weld pool were calculated. Furthermore, the simulated weld bead geometries were in good agreement with experimental measurement.

Temperature dependence of sound velocity in liquid metals

In this article, we report comparisons between theoretical and experimental values of the velocity of sound and its temperature coefficient at the melting temperature for 41 liquid metals using a number of model theories.

Measurement of magnitude and direction of velocity in high-temperature liquid metals. Part II: Experimental measurements

Experimental research work on the application of the sphere melting technique to measure magnitude as well as direction of velocity in liquid metals is the focus of Part II of this series of articles. The sphere melting time is detected by means of a sensing wire, which is connected to a specially designed electrical circuit. A novel apparatus is used whereby liquid metal is rotated with a specified tangential velocity. To measure the magnitude of velocity, the sensing wire of the sphere melting is located at the center of the sphere. To detect the direction of flow, three sensing wires are employed. These wires are placed at strategic locations inside the sphere and detect the melting times at three different locations. The ratio of the melting times of these locations identifies the direction of the flow. The experimental results are compared against model predictions. In addition, an error analysis is carried out to discover the possible sources of error in the detection of metal velocity. The liquid metals used in this research work are commercial purity aluminum and AZ91 magnesium alloy.

Measurement of magnitude and direction of velocity in high-temperature liquid metals. Part I: Mathematical modeling

This article describes the development of a mathematical model that predicts the time required for a metal sphere to melt in a metal bath under different fluid flow conditions. The sphere is made from the same metal as the bath. The model solves numerically the pertinent momentum and energy equations in three dimensions, employing the SIMPLER algorithm. For the case of a pure metal, the model uses the heat integration algorithm to account for the latent heat of fusion. For the situation of a metal alloy with long freezing range, it incorporates the enthalpy method to account for the latent heat of fusion. The model is validated extensively: first, by using Paterson’s analytical solution; second, by using the experimental results of Gallium melting in a rectangular enclosure; and third, by using experimental results involving ice spheres melting in water. The practical use of this model is to study the influence of various parameters in the sphere melting system. This study facilitates the detection of liquid metal velocity using the sphere melting technique.

Two dimensional model for analysis of cylindrical linear induction pump characteristics: model description and numerical analysis

The paper describes a two dimensional numerical model for analysis of the local and integral characteristics of linear electromagnetic pumps, such as magnetic field distribution, pressure developed, amplitude of pressure pulsation with double supply frequency and distribution of liquid metal velocity over the azimuth. Numerical results are compared with experimental ones.

Influence of mercury velocity on compatibility with type 316L/316LN stainless steel in a flow loop

Previous experiments to examine corrosion resulting from thermal gradient mass transfer of type 316L stainless steel in mercury were conducted in thermal convection loops (TCLs) with an Hg velocity of about 1 m/min. These tests have now been supplemented with a series of experiments designed to examine the influence of increased flow velocity and possible cavitation conditions on compatibility. In one experiment, the standard TCL design was modified to include a reduced section in the hot leg that provided a concomitant increase in the local velocity by a factor of five. In addition, a pumped-loop experiment was operated with a flow velocity of about 1 m/s. Finally, a TCL was modified to include an ultrasonic transducer at the top of the hot leg in an attempt to generate cavitation conditions with corresponding extreme local velocity associated with collapsing bubbles. The results indicate that compatibility of type 316L/316LN stainless steel does not depend significantly on liquid metal velocity in the range of 1 m/min to 1 m/s. Benchtop cavitation experiments revealed susceptibility of 316L coupons to significant weight losses and increases in surface roughness as a result of 24 h exposure to 1.5 MPa pressure waves in Hg generated ultrasonically at 20 kHz. However, attempts to generate cavitation conditions on coupons inside the TCL with the ultrasonic transducer proved largely unsuccessful.

The Estimation of Allowable Neutron and Heat Fluxes to the First Wall of the Liquid Metal Fusion Reactor Blanket

Allowable heat and neutron fluxes to the first wall of the fusion reactor blanket with V alloy as a structural material and liquid-metal coolant are estimated in the paper. Dependences of allowable fluxes on liquid metal velocity, poloidal length of the first wall duct, liquid metal heating, the first and back walls thickness are shown. Li and Li-Pb alloy as coolants of the first wall duct are compared.

Liquid Metal Blanket-Related Issues Research in SWIP

In the last decade, liquid metal (LM) blanket-related key issues, such as the magnetohydrodynamics due to reactor off-normal shutdown, LM velocity two-dimensional effect, manifold three-dimensional effect, insulator coating imperfection effect, and so on, have been investigated in experiments and theoretic analysis in Southwestern Institute of Physics (SWIP). Some results were first observed such as the two-dimensional effect and the instabilities due to insulator coating imperfection in this field. These results also related to the advanced limiter-divertor plasma system. In this paper, we review the progress made by SWIP in this research field.

Measuring velocity in high‐temperature liquid metals: a review

All fluid mechanics problems in metals‐processing operations are associated with the measurement of fluid velocity. The development of various models of predicting fluid flow characteristics in complex engineering problems has increased the need for fluid velocity measurements. These measurements provide the necessary validation and tuning for model predictions. In addition, measurement of fluid velocity can be used as a tool for process control purposes. Moreover, the continuous push of metal industries for improved quality and efficiency in liquid metal processing operations, has further highlighted the need for liquid metal velocity measurements. This review presents the various techniques used so far to measure velocity in liquid metals. It outlines the advantages and disadvantages of each technique and provides the reader with information for critical analysis.

A novel resistance measurement technique in the field of directional solidification

A brief review of existing diagnostic methods in directional solidification is first presented. We then discuss the potential of global and differential resistance measurements to determine the interface position and velocity in liquid metals and semiconductors. An electronic design allowing the measurements to be carried out with maximum accuracy is proposed. This design is characterized both at low and high temperatures and it is shown that the peak to peak noise on the resistance signal can be kept of the order of 0.1 μ Ω. In the tin based system used in our investigations, this amounts to an accuracy in terms of solid–liquid interface position in the micrometer range, which represents a significant improvement with respect to existing techniques. We found that such an accuracy allows us to characterize in detail the heat transfer phenomena within our directional solidification furnace, and to identify the thermal lag of the device in the translation and stabilization stages.

Toward a probe for velocity measurement in molten metals at high temperatures

The electromagnetic probe of Ricou and Vives for measurement of velocity in liquid metals is well known. This probe incorporates a permanent magnet. Consequently, the use of the probe at temperatures approaching the Curie temperature of the magnet is difficult. Above that temperature, the probe is inoperable. This article describes a modification of the probe; the permanent magnet was replaced by an electromagnet. The article treats the theory of using an electromagnet and gives an account of experiments in which the principle of the probe was demonstrated by velocity measurements in an alloy with a low melting point. Circuits for measurements with the electromagnet driven by both alternating and direct current are described; better results were obtained with the latter. Two types of probes were examined, one intended for complete submersion in the melt and the other for measurements near the surface of the melt. An air-cooled version was found to withstand external temperatures of 970 K, while the internal temperature remained below 390 K.

Development in the theory and analysis of eddy current sensing of velocity in liquid metals

Abstract We have performed a theoretical study of the magnetic fields produced by a single turn ac coil encircling a moving conductive rod or tube of flowing liquid metal. A solution exact to first order in the velocity has been obtained as a closed-form integral. Radial variation of the velocity profile is included. The solution allows a calculation of the voltages induced in two secondary coils wired in opposition for application as a velocimeter. With secondary coils wired in series, the calculation provides the classical impedance vs. frequency curves which allow determination of sample conductivity and diameter. The solution has been used to optimize design for a sensor to be used for monitoring speed and tube bore diameter in a liquid metal atomizer system. An additional solution has been obtained for arbitrary magnitude of velocity, but for constant velocity profile.

Development in the Theory and Analysis of Eddy Current Sensing of Velocity in Liquid Metals

We have performed a theoretical study of the magnetic fields produced by a single turn ac coil encircling a moving conductive rod or tube of flowing liquid metal. A solution exact to first order in the velocity has been obtained as a closed-form integral. Radial variation of the velocity profile is included. The solution allows a calculation of the voltages induced in two secondary coils wired in opposition for application as a velocimeter. With secondary coils wired in series, the calculation provides the classical impedance vs. frequency curves which allow determination of sample conductivity and diameter. The solution has been used to optimize design for a sensor to be used for monitoring speed and tube bore diameter in a liquid metal atomizer system. An additional solution has been obtained for arbitrary magnitude of velocity, but for constant velocity profile.

Development in the Theory and Analysis of Eddy Current Sensing of Velocity in Liquid Metals

Development in the Theory and Analysis of Eddy Current Sensing of Velocity in Liquid Metals

Acoustic-velocity measurement across the diameter of a liquid-metal column

Present techniques for measuring sound velocity in liquid metals have been limited by the use of transducers which cannot survive in extreme-temperature conditions. These methods also require relatively long measurement times. An optical noncontacting method has been developed which may be used for extremely short experimental times and very high temperatures and pressures. This technique is being incorporated into an isobaric-expansion apparatus in which a 1-mm-diam wire sample in a high-pressure argon-gas environment is resistively heated to melt within a time period of only a few microseconds. Before instability of the liquid column occurs, thermal expansion, enthalpy and temperature are measured. The addition of the sound-velocity measurement permits a more complete determination of the thermophysical properties of the liquid metal.

A New Technique for Measuring the Velocity of Sound in Liquid Metals

Since piezoelectric transducers cease to function above 600 °C, velocity of sound measurements become difficult at high temperatures. Many of the difficulties may be circumvented by observing the acoustic waves using the electromagnetic detection technique. This method has been made the basis of an apparatus with which the sound velocity in liquid metals may be measured with an accuracy of 0.1% up to a temperature of 1300 °C. Results for liquid copper and tin are presented, to illustrate the value of the technique.

Calculated ultrasound velocity in liquid metals

Calculated ultrasound velocity in liquid metals