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This investigation aims to analyze the steel-flux interface level fluctuation because of electromagnetic stirring and its process parameters in a continuous casting billet mold.

An un-coupled numerical model for electromagnetic field generation and a coupled numerical model of electromagnetic field and two-phase fluid flow have been developed. The two-phase fluid flow has been modeled using volume of fluid method, in which externally generated time-varying electromagnetic field is coupled and analyzed using magnetohydrodynamic method. Top surface standing wave stability criteria are used to study the criticality of interface stability.

Results show that application electromagnetic field for stirring increases the interface level fluctuation, specifically at the mold corners and near the submerged entry nozzle. The increase in current intensity and stirrer width barely affect the interface level. However, interface level fluctuation increases considerably with increase in frequency. Using stability criteria, it is found that at 20 Hz frequency, the ratio of height to wavelength of interface wave increases much above the critical value. The iso-surface of the interface level shows that at 20 Hz frequency, mold flux gets entrapped into the liquid steel.

The model may be used during optimization of in-mold electromagnetic stirrer to avoid mold flux entrapment and control the cast quality.

The study of mold level fluctuation in the presence of in-mold electromagnetic stirrer has rarely been reported. The criticality of stirrer process parameters on level fluctuation has not been yet reported. This study lacks in experimental validation; however, the findings will be much useful for the steelmakers to reduce the casting defects.

The purpose of present investigation is to analyze the in-mold electromagnetic stirring (M-EMS) process and the effect of stirrer frequency on fluid flow and solidification in a continuous casting billet caster mold.

A hybrid approach involving finite element and finite volume method has been used for the study. Finite element model is used to calculate time variable magnetic field, which is further coupled with fluid flow and solidification equations for magneto-hydrodynamic analysis with finite volume model.

Results show that though superheat given to steel before its entry into the mold is quickly removed, solid shell formation is delayed by the use of M-EMS. Final solid shell thickness, however, is slightly reduced. Increase in frequency is found to increase the magnetic flux density and tangential velocity of liquid steel and decrease in diameter of liquid core.

The work is of great industrial relevance. The model may be used to design industrial setup of in-mold electromagnetic stirrer and process could be analyzed and optimized numerically.

The paper evaluates the influence of M-EMS and its frequency on solidification and flow behavior in the continuous casting mold. The iso-surface temperatures from pouring temperature to liquidus temperature inside the mold have been shown. The findings may be useful for the steelmakers to reduce the defect in continuous casting.

Stir casting is a promising technique used for the manufacture of Al-SiC metal matrix composites. The clustering of reinforcement particles is a serious concern in this production method. In this work, mushy-state solidification characteristics in stir casting are numerically simulated using computational fluid dynamics techniques to study the clustering of reinforcement particles.

Effects of process parameters on the distribution of particles are examined by varying stirrer speed, volume fraction of reinforcement, number of blades on stirrer and diameter ratio (ratio of crucible diameter to stirrer diameter). Further, investigation of characteristics of cooling curves during solidification process is carried out. Volume of fluid method in conjunction with a solidification model is used to simulate the multi-phase fluid flow during the mushy-state solidification. Solidification patterns thus obtained clearly indicate a strong influence of process parameters on the distribution of reinforcement particles and solidification time.

From the simulation study, it is observed that increase in stirrer speed from 50 to 150 rad/s promotes faster solidification rate. But, beyond 100 rad/s, stirrer speed limit, clustering of reinforcement particles is observed. The clustering of reinforcement particles is seen when volume fraction of reinforcement is increased beyond 10 per cent. When number of blades on stirrer are increased from three to five, an increase in solidification rate is observed, and an uneven distribution of reinforcement particles are observed for five-blade geometry. It is also seen from the simulation study that a four-blade stirrer gives a better distribution of reinforcement in the molten metal. Decrease in diameter ratio from 2.5 to 1.5 promotes faster solidification rate.

There is 90 per cent closeness in results for simulation study and the published experimental results.

The purpose of this study is to develop a novel rectangular linear induction motor as an electromagnetic stirrer (EMS) using analytical followed by a numerical approach. The rectangular linear electromagnetic stirrer (RLEMS) is mainly developed for rectangular slab and billet as the end product.

A two-dimensional analytical approach for evaluating flux density distribution within the mold is established for RLEMS structure. Subsequently, the average stirring force within the mold is estimated from those field variables. The paper presents an analytical and numerical model for calculating the stirring force and counters the end and edge effects of linear-type EMS. Magnetic field and force profile within the mold due to polyphase rectangular stator distribution has been done with the help of Maxwell’s equation with appropriate boundary conditions by using Fourier transform and inverse Fourier transform. Subsequently, a numerical study has been carried out using a coupled thermal and electromagnetic model.

The present study investigates the physical phenomena during the solidification process because of an induced electromagnetic field and is able to extract all the electromagnetic field variables under different operating conditions, and, subsequently, provides an insight into the actual happening within the mold.

It provides the analytical method for solving the stirring force of the proposed new RLEMS structure by addressing the smooth and efficient variation of field and velocity profile near the corner of the mold and improves the quality of end product.

Higher expectations in the performance of modern stirrer bead mills in respect of particle fineness, grit size distribution, larger proportion of pigments and consequently higher viscosity, currently have a considerable influence on the design and construction of new mills. Higher demands on the machine itself, such as low wear rate and low grinding temperatures have also set new trends in the development of these mills.

The purpose of this paper is to search optimal shape of soft magnetic composite-based inserts used to compensate the working gap between the liquid metal and the induction stirrer in metallurgical installations.

The study was based on numerical simulation of electromagnetic processes in frequency domain. To optimize inserts shape, the Nelder–Mead method was used. The maximum of integral electrodynamic force along x-axis was chosen as the objective function. All simulations were performed in finite element software package Comsol Multiphysics.

Optimal inserts shape was determined, at which the value of integral electrodynamic force along x-axis increased by 20% from 692  to 792 N.

Magnetic concentrators based on soft magnetic composite materials have long been used in high-frequency systems; at the same time, their use in low-frequency systems has not been previously considered in detail. The study of the shape effect of concentrators on the effectiveness of electromagnetic field in a liquid metal in a three-dimensional formulation was carried out for the first time.

The adverse effects of temperature on the lubricating properties of nano magnetorheological grease are reduced by applying of a magnetic field.

Nano magnetorheological grease was prepared via a thermal water bath with stirring. The lubricating properties of the grease were investigated at different temperatures. Then the lubricity of the prepared nano magnetorheological grease was investigated under the effect of thermomagnetic coupling.

As the temperature rises, the coefficient of friction of grease lubrication gradually increases, surface wear gradually increases and lubrication performance gradually decreases. Compared with grease, magnetorheological grease has a decreased coefficient of friction and enhanced lubrication effect under the action of a magnetic field at different temperatures.

A lubrication method using a magnetic field to reduce the effect of temperature is established, thereby providing new ideas for lubrication design under a wide range of temperature conditions.

The Secretary of State:—

THE improvement in the British standard of living is generally desired. Politicians have not only subscribed to that ideal but some of them have indicated the rate at which we should advance. There are, however, certain trends in the country's economic life which must be reversed if we are to make any progress in that direction.

FRYMA‐Maschinen AG, Rheinfelden/Switzerland, is a leading manufacturer of special machines and units for wet grinding, dispersing, heat exchange and vacuum deaeration.