scholarly journals Self-excitation in a helical liquid metal flow: the Riga dynamo experiments

2018 ◽  
Vol 84 (3) ◽  
Author(s):  
A. Gailitis ◽  
G. Gerbeth ◽  
Th. Gundrum ◽  
O. Lielausis ◽  
G. Lipsbergs ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Numerical Simulations ◽  
20Th Century ◽  
Metal Flow ◽  
Magnetic Field Generation ◽  
Kinematic Dynamo ◽  
Liquid Metal Flow ◽  
Comprehensive Survey ◽  
Dynamo Effect

The homogeneous dynamo effect is at the root of magnetic field generation in cosmic bodies, including planets, stars and galaxies. While the underlying theory had increasingly flourished since the middle of the 20th century, hydromagnetic dynamos were not realized in the laboratory until 1999. On 11 November 1999, this situation changed with the first observation of a kinematic dynamo in the Riga experiment. Since that time, a series of experimental campaigns has provided a wealth of data on the kinematic and the saturated regime. This paper is intended to give a comprehensive survey about these experiments, to summarize their main results and to compare them with numerical simulations.

Numerical Simulations and Experimental Study of Liquid Metal Flow Around Sand Core

2005 ◽  
Vol 128 (3) ◽  
pp. 541-547
Author(s):  
Sayavur I. Bakhtiyarov
Keyword(s):  
High Temperature ◽  
Liquid Metal ◽  
Numerical Simulations ◽  
Buoyancy Force ◽  
Metal Flow ◽  
Tensile Tests ◽  
Metal Casting ◽  
Sand Core ◽  
Liquid Metal Flow ◽  
Cold Box

This paper presents the results of experimental and numerical studies of the hot distortion phenomenon in the phenolic urethane cold box systems used in metal casting. Dual Pushrod Dilatometry has been used to measure a thermal expansion/contraction of phenolic urethane cold box sand core specimens at temperatures ranging from 20°C to 600°C. High temperature tensile tests showed that the tensile strength of the phenolic urethane cold box sand cores is significantly affected by the bench life, temperature and binders level. High temperature hot distortion furnace tests on cylindrical cores showed that some coatings increase the temperature limit when distortion starts, but application of coating cannot prevent distortion. The hot distortion test during metal casting showed that regardless of the application of coating, the type of coating, and anti-veining additives, all cores with density greater than the density of the molten metal (magnesium alloy) were significantly distorted. Numerical simulations of the liquid metal flow around the cylindrical sand core and analysis of dynamic forces acting on the core during the fill process showed that a buoyancy force is the major contributor to the hot distortion. It is concluded that the one of the solutions in preventing the hot distortion of sand cores is optimizing their weight, which will balance the buoyancy force and will bring the resultant force to the minimum. The hot distortion test castings using optimized sand cores with density almost equal to the density of the molten magnesium proved our predictions, and hot distortion has been prevented.

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