Gantayet A. Article First Online: 08 June PACS Nos This is a preview of subscription content, log in to check access. Satyamurthy 1 L. Gantayet 1 A.
Ray 1 1. Personalised recommendations. Cite article How to cite? We have shown that, depending on forcing conditions, a statistically stationary dynamo, or dynamical regimes of magnetic field can be generated.
In particular, polarity reversals similar to those of Earth's magnetic field were observed. Meanwhile, experiment with Gallium has been developed to study the effects of electromagnetic induction by turbulent flows in a more homogeneous and isotropic configuration than in the VKS experiment. Using data from these two experiments, we studied the advection of magnetic field by a turbulent flow and the induced fluctuations. The development of probes measuring electrical potential difference allowed us to further highlight the magnetic braking of a turbulent flow of Gallium by Lorentz force.
This mechanism is involved in the saturation of the dynamo instability. Generation of electricity using liquid metal magnetohydrodynamics.
With liquid metal magnetohydrodynamics , a column of molten lead is passed through a magnetic field, thereby generating a voltage potential according to Faraday's law. The molten lead is propelled through a closed loop by steam from water injected just above where the lead is heated at the bottom of the loop. This water in turn boils explosively, propelling the lead upward through the loop and past the point where the steam escapes through a separator.
With the DC current generated by LMMHD, industriell cogeneration is seen as the most likely application, where the byproduct steam still has enough pressure to also power other steam-driven machinery. Furthermore, the byproduct steam is essentially lead-free since the operating temperature of the LMMHD generator is well below the temperature where lead could dissolve into the steam.
Magnetohydrodynamic instability of a cylindrical liquid-metal brush. The stability of a homopolar generator brush, consisting of a liquid-metal -filled cavity between rotating rotor and fixed stator cylinder electrodes, is analyzed in the presence of radial current transport and an axial homogeneous magnetic field.
Within the frame of linear magnetohydrodynamics , it is shown that the liquid-metal flow in the brush is always unstable if the brush transports current. In the absence of current flow infinite load the axial magnetic field stabilizes the liquid-metal flow in the brush if the magnetic energy density is larger than a certain fraction of the energy density of the rotating fluid.
We present an experiment designed to study magnetohydrodynamic effects in free-surface channel flow. The wide aspect ratio channel the width to height ratio is about 15 is completely enclosed in an inert atmosphere to prevent oxidization of the liquid metal. A custom-designed pump reduces entrainment of oxygen, which was found to be a problem with standard centrifugal and gear pumps. Laser Doppler Velocimetry experiments characterize velocity profiles of the flow.
Various flow constraints mitigate secondary circulation and end effects on the flow. Measurements of the wave propagation characteristics in the liquid metal demonstrate the surfactant effect of surface oxides and the damping of fluctuations by a cross-channel magnetic field. Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device. A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic MHD device.
The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents.
Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output. Some problems in the magnetohydrodynamics of liquid metals. When electric currents are caused to flow in an electrically conducting fluid, either by the external application of time-periodic magnetic fields or by the application of large electric potential gradients at the boundary, the associated Lorentz force is in general rotational and a fluid motion, which may be laminar or turbulent, is in general established.
Three prototype problems, on which some progress has been made over the last decade, are reviewed: i the problem of the generation of rotation in a liquid metal by the application of a rotating magnetic field; ii the generation of cellular motion by the application of an alternating field of fixed direction; and iii the problem of the generation of fluid motion by the injection of steady current at a point electrode on the fluid boundary.
All three problems are of importance in molten metal technology. The magnetohydrodynamic force experienced by spherical iron particles in liquid metal. The paper contains a theoretical investigation of magnetohydrodynamic force experienced by iron particles well-conducting and ferromagnetic in well-conducting liquid. The investigation is performed by extending the Leenov and Kolin's theory to take into account the second-order effect. Therefore, the limits of the parent model are taken over to the present results. It is found that the effective conductivity of iron particles in liquid metal , which is important for practical application of the theoretically obtained force, is approximately equal to 1.
The last result is obtained using a quasi-empirical approach — a comparison of experimental results with the results of the numerical simulation that was performed for various conductivities of the iron particles. Three-dimensional MHD [ magnetohydrodynamic ] flows in rectangular ducts of liquid-metal -cooled blankets. Magnetohydrodynamic flows of liquid metals in rectangular ducts with thin conducting walls in the presence of strong nonuniform transverse magnetic fields are examined.
The interaction parameter and Hartmann number are assumed to be large, whereas the magnetic Reynolds number is assumed to be small. Under these assumptions, viscous and inertial effects are confined in very thin boundary layers adjacent to the walls.
A significant fraction of the fluid flow is concentrated in the boundary layers adjacent to the side walls which are parallel to the magnetic field. This paper describes the analysis and numerical methods for obtaining 3-D solutions for flow parameters outside these layers, without solving explicitly for the layers themselves. Numerical solutions are presented for cases which are relevant to the flows of liquid metals in fusion reactor blankets.
In general, the agreement is excellent. Nanoparticle dispersion in liquid metals by electromagnetically induced acoustic cavitation. Aim of this study is to investigate experimentally the effect of magnetically induced cavitation applied for the purpose of nanoparticle dispersion in liquid metals. The oscillating magnetic force due to the azimuthal induction currents and the axial magnetic field excites power ultrasound in the sample. If the fields are sufficiently high then it is possible to achieve the acoustic cavitation threshold in liquid metals.
Cavitation bubble collapses are known to create microscale jets with a potential to break nanoparticle agglomerates and disperse them. The samples are solidified under the contactless ultrasonic treatment and later analyzed by electron microscopy and energy-dispersive X-ray spectroscopy EDX. It is observed that SiC nanoparticles are dispersed in an aluminum magnesium alloy, whereas in tin the same particles remain agglomerated in micron-sized clusters despite a more intense cavitation. Dispersion relations of the acoustic modes in divalent liquid metals.
Directory of Open Access Journals Sweden. Using our experimental technique to prepare proper sample cells and high performance of an IXS beamline BL35XU at SPring-8 in Japan, the dynamic structure factor with reasonable statistics was obtained for these divalent liquid metals.
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For both liquids, the dynamic structure factor at low Q exhibits a central peak with a shoulder or small hump clearly visible on each side, and the inelastic excitation energy determined using the model function composed of Lorentzian and the damped harmonic oscillator function disperses with increasing Q. The dispersion curves of these liquids were compared with that of the longitudinal acoustic phonon in each crystalline phase.
From these results, clear difference in the interatomic interaction be- tween liquid Ca and liquid Cd was inferred. Liquid metal magnetohydrodynamic flows in manifolds of dual coolant lead lithium blankets.
Helium is employed to cool the first wall and the blanket structure. Some critical issues for the feasibility of this blanket concept are related to complex induced electric currents and 3D magnetohydrodynamic MHD phenomena that occur in distributing and collecting liquid metal manifolds. They can result in large pressure drop and undesirable flow imbalance in parallel poloidal ducts forming blanket modules.
In the present paper liquid metal MHD flows are studied for different design options of a DCLL blanket manifold with the aim of identifying possible sources of flow imbalance and to predict velocity and pressure distributions. Numerical Investigation of magnetohydrodynamic flow through Sudden expansion pipes in Liquid Metal Blankets.
In fusion liquid metal blanket, sudden expansions and sudden contractions are very common geometries. Changing of the cross-section causes 3-D magnetohydrodynamic MHD effects, which will affect the flow pattern, current distribution and pressure drop. In this paper the numerical code based on OpenFOAM platform developed by University of Science and Technology of China was used to investigate and optimize the sudden expansion pipe.
The obtained numerical results agreed well with those of all the benchmark cases. Previous and valuable analytical and experimental works have been done by L. Buhler, et. Based on these works, in the present paper, further investigation of different expansion lengths between the upstream pipe and downstream pipe at high Hartmann number and Reynolds number were conducted.
Besides, different expansion ratios with a specific expansion length were conducted. The numerical results showed that with the increasing of expansion length, the 3D MHD effects gradually weakened. Especially, the 3D pressure drop decreases with the increasing of expansion length.
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Whereas, the expansion ratio factor shows no obvious influences on the total MHD pressure drop but greatly influence the local pressure distribution. These numerical simulations can be used to evaluate the MHD flow inside the expansion and contraction pipes. Magnetohydrodynamic pressure drop and flow balancing of liquid metal flow in a prototypic fusion blanket manifold.
Heavy density liquid metal spallation target studies for indian ADS programme
Understanding magnetohydrodynamic MHD phenomena associated with the flow of electrically conducting fluids in complex geometry ducts subject to a strong magnetic field is required to effectively design liquid metal LM blankets for fusion reactors. Particularly, accurately predicting the 3D MHD pressure drop and flow distribution is important. The reference manifold geometry consists of a rectangular feeding duct which suddenly expands such that the duct thickness in the magnetic field direction abruptly increases by a factor rexp.
Downstream of the sudden expansion, the LM is distributed into several parallel channels. Scaling laws have been obtained which characterize the 3D MHD pressure drop and flow balancing as a function of the flow parameters and the manifold geometry. An accurate model for the pressure drop was developed for the first time for inertial-electromagnetic and viscous-electromagnetic regimes based on 96 computed cases.