The behaviour of gas bubbles in a turbulent liquid metal magnetohydrodynamic flow: Part I: Dispersion in quasi-two-dimensional magnetohydrodynamic turbulence

The behaviour of gas bubbles in a turbulent liquid metal magnetohydrodynamic flow: Part II: Magnetic field influence on the slip ratio

Single-phase and two-phase magnetohydrodynamic pipe flow

The gas-liquid slip ratio and the MHD pressure drop in the two-phase liquid metal flow under a strong magnetic field are treated in relation to the distributions of the gaseous phase and the fluid velocity. From NaK-N2 two-phase experiments, it is found that: 1. The ratio of the two-phase MHD pressure drop to that of the homogeneous non-slip two-phase flow model is independent of the applied magnetic field strength and the channel geometry (ratio of wall thickness to channel width) and is presented as a function of the ratio of the gas-liquid volumetric flow rate. 2. The void distribution is affected by the applied magnetic field. The gas bubbles may be pushed away towards the both side walls due to the pinch effect, resulting in the increase of the ratio of the mean void fraction to the one at the channel center with the increasing applied magnetic field. 3. The gas-liquid slip ratio is not directly dependent on the applied magnetic field strength and the channel geometry and is presented as a function o...

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Gas-Liquid Slip Ratio and MHD Pressure Drop in Two-Phase Liquid Metal Flow in Strong Magnetic Field

Currently, Russia, India, China, France, South Korea, and Japan are actively pursuing liquid metal cooled applications such as liquid cooled metal nuclear reactor concepts. The liquid metal coolants being considered for these designs are sodium, lead and lead-bismuth eutectic; these designs utilize reactive and toxic materials at temperatures up to 1073 K for nuclear power plant operations and other similar applications. To simulate these systems with the actual coolant material requires a high level of safety systems. Use of these materials in university experimental laboratory settings is difficult due to the safety hazards and that lead (Pb) is a designated substance requiring special permission to use. Therefore, a less toxic and less reactive liquid metal that can be used to simulate liquid metal cooled flows will allow for a greater number of investigations and experimentation of liquid metal flow with regards to the field of thermal hydraulics. Good candidates for a liquid metal experimental fluid are alloys from the indium-bismuth-tin system such as Fields metal, which by weight percent is 51% indium, 32.5% bismuth and 16.5% tin and possesses a melting temperature of 333 K. However, the thermodynamic properties of Fields metal and similar alloys in their liquid state are not well described in literature. This work experimentally measures the specific heat of the eutectic alloys of theindium-bismuth-tin tertiary system using a differential scanning calorimeter technique and analyzes the results to determine if the thermodynamic properties of the system have sufficient scaling for experimental modeling applications. The results verify the melting temperatures of the alloys and establish a relationship between temperature and specific heat.

Determination of Specific Heat of Eutectic Indium – Bismuth-Tin Liquid Metal Alloys as a Test Material for Liquid Metal - Cooled Applications

https://www.tandfonline.com/doi/pdf/10.1080/18811248.1972.9734939

Electrical Conductivity of Liquid Metal Two-Phase Mixture in Bubbly and Slug Flow Regime

In this paper, the frictional pressure drop in an isothermal liquid metal-gas two-phase flow through a rectangular channel with large width-to-height ratio is treated semiempirically for a NaK-N2 two-phase flow system. The frictional pressure drop in the two-phase flow is compared with the following two reference values : 1. The frictional pressure drop in the liquid flowing alone in single phase with the same velocity as that of the liquid in the two-phase mixture. 2. The frictional pressure drop in the liquid flowing alone in single phase with the same mass flow rate as that of the liquid in the two-phase mixture. The comparison with the former reference value is necessary for the prediction of friction loss in a liquid metal MHD generator channel whose medium would be two-phase mixture. The semiempirical analysis was performed assuming the two-phase mixture to be a continuous medium with its properties, e.g. viscosity and density, defined by void fraction and the velocity determined by the total mass f...

Frictional Pressure Drop for NaK-N2 Two-Phase Flow in Rectangular Cross Section Channel of Large Aspect Ratio

In this paper, the performance characteristics of a linear channel LM-MHD induction converter operated in both constant current and constant voltage mode are obtained analytically, appling the slit channel approximation but taking account of variations in the traveling magnetic field intensity in the direction of the fluid flow according to differences in the disposition of the teeth and slots in the stators. The analytically obtained solutions were verified with the experimental converter with and without copper side bars operated in constant voltage mode at room temperature using NaK-78 as the electrically conducting working fluid. The experimental results obtained with the converter with copper side bars agreed with the analytically obtained solutions, though the plots of power output shifted toward greater values of negative slip compared with the theoretical curves, due to the additional ohrnic losses in both the side walls of channel and the copper side bars, which were not taken into account in the...

Energy Loss in Liquid Metal MHD Induction Converter due to Discrete Tooth-Slot Arrangements

In the liquid metal MHD power generator, the electric conductivity of the working fluid is so large as to be comparable with that of the electrode. Under such circumstances the perfect conductor approximation no longer holds for the electrode, because the electric potential loses its constancy and acquires a certain pattern of distribution in the electrode as well as in the fluid. The extent of distortion in the electric equipotential lines and lines of force depends on the ratio of conductivity between electrode and fluid, and on the load connection. The power density becomes non-uniform, and furthermore the average power density becomes smaller than in the case of a generator with the perfect conductor electrode. The effect due to this finite conductivity of the electrode is contrary in trend to that due to end loss, as analyzed by Sutton with both aspect ratio and load factor as parameters. The results obtained in our present experiments with a mercury blow-down facility have agreed very well with the ...

https://www.jstage.jst.go.jp/article/jnst1964/8/10/8_10_588/_pdf

Nobuhiro Tanatugu

Papers

Electrical Conductivity of Liquid Metal Two-Phase Mixture in Bubbly and Slug Flow Regime

Frictional Pressure Drop for NaK-N2 Two-Phase Flow in Rectangular Cross Section Channel of Large Aspect Ratio

Energy Loss in Liquid Metal MHD Induction Converter due to Discrete Tooth-Slot Arrangements

Decrease in Power Density due to Finite Electrode Conductivity in Liquid Metal MHD Generator