Equilibrium magnetohydrodynamic flows of liquid metals in magnetorotational instability experiments

2010 ◽  
Vol 644 ◽  
pp. 257-280 ◽  
Author(s):  
I. V. KHALZOV ◽  
A. I. SMOLYAKOV ◽  
V. I. ILGISONIS
Keyword(s):  
Liquid Metal ◽  
Theoretical Analysis ◽  
Liquid Metals ◽  
Annular Channel ◽  
Reynolds Numbers ◽  
Unified Approach ◽  
Magnetorotational Instability ◽  
Annular Channels ◽  
Magnetohydrodynamic Flows ◽  
Different Types

A theoretical analysis of equilibrium magnetohydrodynamic flows in annular channels is performed from the perspective of establishing required conditions for liquid metal magnetorotational instability (MRI) experiments. Two different types of fluid rotation are considered: electrically driven flow in an annular channel and Taylor–Couette flow between rotating cylinders. The structure of these flows is studied within a unified approach as a function of the Hartmann and Reynolds numbers. The parameters appropriate for realization of MRI experiments are determined.

Theoretical and Experimental Investigations of Coolant Flow in Inlet Channels of the BTA and Ejector Drills

1995 ◽  
Vol 209 (3) ◽  
pp. 211-220 ◽  
Author(s):  
V P Astakhov ◽  
P S Subramanya ◽  
M O M Osman
Keyword(s):  
Axial Flow ◽  
Annular Channel ◽  
Reynolds Numbers ◽  
Coolant Flow ◽  
Experimental Investigations ◽  
Annular Channels ◽  
Critical Reynolds Numbers ◽  
Flow Through ◽  
The Stability ◽  
The Mathematical Model

The coolant flow through inlet annular channels in BTA and ejector drills is investigated. The study was conducted in order to understand the influence of the channel's parameters (the channel's clearance variation along its length and eccentricity) on the coolant pressure distribution and hydraulic resistance. A new design of the ejector drill with the eccentrical location on the inner tube is proposed. A study is made of the stability in the coolant flow in the inlet annular channels. The appearance of instability is explained by the presence of Taylor macrovortices in these channels under certain combinations of boring bar rotating velocity and axial flow velocity. In order to define the unstable regimes (the critical Reynolds numbers), the mathematical model for non-isothermal flow through the annular channel is solved. The heat transfer from the swarf to the incoming coolant is investigated under different flow conditions.

Effects of slowly varying meniscus curvature on internal flows in the Cassie state

2019 ◽  
Vol 872 ◽  
pp. 272-307 ◽  
Author(s):  
Simon E. Game ◽  
Marc Hodes ◽  
Demetrios T. Papageorgiou
Keyword(s):  
Liquid Metal ◽  
Small Parameter ◽  
Cross Section ◽  
Flow Rate ◽  
Pressure Difference ◽  
Liquid Metals ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Local Conditions ◽  
Cassie State

The flow rate of a pressure-driven liquid through a microchannel may be enhanced by texturing its no-slip boundaries with grooves aligned with the flow. In such cases, the grooves may contain vapour and/or an inert gas and the liquid is trapped in the Cassie state, resulting in (apparent) slip. The flow-rate enhancement is of benefit to different applications including the increase of throughput of a liquid in a lab-on-a-chip, and the reduction of thermal resistance associated with liquid metal cooling of microelectronics. At any given cross-section, the meniscus takes the approximate shape of a circular arc whose curvature is determined by the pressure difference across it. Hence, it typically protrudes into the grooves near the inlet of a microchannel and is gradually drawn into the microchannel as it is traversed and the liquid pressure decreases. For sufficiently large Reynolds numbers, the variation of the meniscus shape and hence the flow geometry necessitates the inclusion of inertial (non-parallel) flow effects. We capture them for a slender microchannel, where our small parameter is the ratio of ridge pitch-to-microchannel height, and order-one Reynolds numbers. This is done by using a hybrid analytical–numerical method to resolve the nonlinear three-dimensional (3-D) problem as a sequence of two-dimensional (2-D) linear ones in the microchannel cross-section, allied with non-local conditions that determine the slowly varying pressure distribution at leading and first orders. When the pressure difference across the microchannel is constrained by the advancing contact angle of the liquid on the ridges and its surface tension (which is high for liquid metals), inertial effects can significantly reduce the flow rate for realistic parameter values. For example, when the solid fraction of the ridges is 0.1, the microchannel height-to-(half) ridge pitch ratio is 6, the Reynolds number of the flow is 1 and the small parameter is 0.1, they reduce the flow rate of a liquid metal (Galinstan) by approximately 50 %. Conversely, for sufficiently large microchannel heights, they enhance it. Physical explanations of both of these phenomena are given.

scholarly journals On fluid flows in precessing narrow annular channels: asymptotic analysis and numerical simulation

2010 ◽  
Vol 656 ◽  
pp. 116-146 ◽  
Author(s):  
KEKE ZHANG ◽  
DALI KONG ◽  
XINHAO LIAO
Keyword(s):  
Asymptotic Expression ◽  
Three Dimensional ◽  
Annular Channel ◽  
Reynolds Numbers ◽  
Quantitative Agreement ◽  
Small Scale ◽  
Two Dimensional ◽  
Nonlinear Simulation ◽  
Annular Channels ◽  
Asymptotic Expressions

We consider a viscous, incompressible fluid confined in a narrow annular channel rotating rapidly about its axis of symmetry with angular velocity Ω that itself precesses slowly about an axis fixed in an inertial frame. The precessional problem is characterized by three parameters: the Ekman number E, the Poincaré number ε and the aspect ratio of the channel Γ. Dependent upon the size of Γ, precessionally driven flows can be either resonant or non-resonant with the Poincaré forcing. By assuming that it is the viscous effect, rather than the nonlinear effect, that plays an essential role at exact resonance, two asymptotic expressions for ε ≪ 1 and E ≪ 1 describing the single and double inertial-mode resonance are derived under the non-slip boundary condition. An asymptotic expression describing non-resonant precessing flows is also derived. Further studies based on numerical integrations, including two-dimensional linear analysis and direct three-dimensional nonlinear simulation, show a satisfactory quantitative agreement between the three asymptotic expressions and the fuller numerics for small and moderate Reynolds numbers at an asymptotically small E. The transition from two-dimensional precessing flow to three-dimensional small-scale turbulence for large Reynolds numbers is also investigated.

Liquid metal experiments on the magnetorotational instability

2009 ◽  
Vol 45 (2) ◽  
pp. 135-144 ◽  
Author(s):  
F. Stefani ◽  
G. Gerbeth ◽  
Th. Gundrum ◽  
J. Szklarski ◽  
G. Rüdiger ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Magnetorotational Instability

Liquid metal-based nanocomposite materials: Fabrication technology and applications

Nanoscale ◽  
2021 ◽  
Author(s):  
Hiroki Ota ◽  
Nyamjargal Ochirkhuyag ◽  
Ryosuke Matsuda ◽  
Zihao Song ◽  
Fumika Nakamura ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Flexible Electronics ◽  
Liquid Metals ◽  
Nanocomposite Materials ◽  
Fabrication Technology

Research on liquid metals has been steadily garnering more interest in recent times because the properties of these metals are conducive to flexible electronics applications; further, these metals are in...

scholarly journals Liquid Metals: Liquid Metal Marbles (Adv. Funct. Mater. 2/2013)

2013 ◽  
Vol 23 (2) ◽  
pp. 137-137 ◽  
Author(s):  
Vijay Sivan ◽  
Shi-Yang Tang ◽  
Anthony P. O'Mullane ◽  
Phred Petersen ◽  
Nicky Eshtiaghi ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Liquid Metals

Occurrence of Bubbles in a Thin Wire at Low Reynolds Number

1992 ◽  
Vol 114 (2) ◽  
pp. 255-260 ◽  
Author(s):  
K. Sato
Keyword(s):  
Separation Zone ◽  
Reynolds Numbers ◽  
Cavitation Number ◽  
The Other ◽  
Laminar Separation ◽  
Low Reynolds Numbers ◽  
Thin Wires ◽  
Different Types ◽  
Low Reynolds ◽  
Air Diffusion

Thin wires of various diameters from 0.07 to 0.7 mm are examined about appearances and characteristics of bubble occurrence behind them in the range of low Reynolds numbers. The appearance of bubbles is very dependent on diameters of wires. Two different types of bubbles can be observed in the present experiment. One is a streamer-type bubble for smaller wires and the other is a small unspherical bubble for larger wires. The incipient and the desinent values of cavitation number also change greatly with the bubble types. The streamer-type bubble is related to the presence of laminar separation zone and the growth due to air diffusion. The small unspherical bubble can be mainly attributed to the motion of rolled-up vortices and the growth due to vaporization.

Unusual Wetting Behavior of Liquid Metals on Porous Layer Formed at Surface of Iron Substrate Prepared by Oxidation-Reduction Process

2007 ◽  
Vol 561-565 ◽  
pp. 1699-1701
Author(s):  
Nobuyuki Takahira ◽  
Takeshi Yoshikawa ◽  
Toshihiro Tanaka
Keyword(s):  
Liquid Metal ◽  
Porous Layer ◽  
Liquid Metals ◽  
Reduction Process ◽  
Surface Oxidation ◽  
Porous Iron ◽  
Normal Contact ◽  
Wetting Behavior ◽  
Oxidation Reduction ◽  
Oxidized Iron

Unusual wetting behavior of liquid Cu was found on a surface-oxidized iron substrate in reducing atmosphere. Liquid Cu wetted and spread very widely on the iron substrate when a droplet was attached with the substrate in Ar-10%H2 after the surface oxidation of the substrate. The oxidationreduction process fabricates a porous layer at the surface of the iron substrate. The pores in the porous iron layer are 3-dimensionally interconnected. Thus, liquid metals, which are contacted with the reduced iron samples, penetrate into these pores by capillary force to cause the unusual wetting behavior. It has been already confirmed that liquid Ag, Sn, In and Bi show this phenomenon onto surface-porous iron samples as well as liquid Cu. This unusual wetting behavior of a liquid metal has been correlated to the normal contact angle of the liquid metal on a flat iron substrate.

Suitability of Eutectic Field’s Metal for Use in an Electromagnetohydrodynamically-Enhanced Experimental Two-Phase Flow Loop

2012 ◽  
Author(s):  
A. Lipchitz ◽  
Lilian Laurent ◽  
G. D. Harvel
Keyword(s):  
Liquid Metal ◽  
Two Phase Flow ◽  
Nuclear Reactors ◽  
Liquid Metals ◽  
Metal Flow ◽  
Phase Flow ◽  
Laboratory Setting ◽  
Flow Loop ◽  
Fast Reactors ◽  
Two Phase

Several Generation IV nuclear reactors, such as sodium fast reactors and lead-bismuth fast reactors, use liquid metal as a coolant. In order to better understand and improve the thermal hydraulics of liquid metal cooled GEN IV nuclear reactors liquid metal flow needs to be studied in experimental circulation loops. Experimental circulation loops are often located in a laboratory setting. However, studying liquid metal two phase flow in laboratory settings can be difficult due to the high temperatures and safety hazards involved with traditional liquid metals such as sodium and lead-bismuth. One solution is to use a low melt metal alloy that is as benign as reasonably achievable. Field’s metal is a eutectic alloy of 51% Indium, 32.5% Bismuth and 16.5% Tin by weight and has a melting point of 335K making it ideal for use in a laboratory setting. A study is undertaken to determine its suitability to use in a two-phase experimental flow loop enhanced by magnetohydrodynamic forces. The study investigated its reactivity with air and water, its ability to be influenced by magnetic fields, its ability to flow, and its ease of manufacture. The experiments melted reference samples of Field’s metal and observed its behaviour in a glass beaker, submerged in water and an inclined stainless steel pipe. Then Field’s metal was manufactured in the laboratory and compared to the sample using the same set of experiments and standards. To determine Field’s metal degree of magnetism permanent neodymium magnets were used. Their strength was determined using a Gaussmeter. All experiments were recorded using a COHU digital camera. Image analysis was then performed on the video to determine any movements initiated by the magnetic field forces. In conclusion, Field’s metal is more than suitable for use in experimental settings as it is non-reactive, non-toxic, simple to manufacture, easy to use, and responds to a magnetic force.

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