Electromagnetic Brake Research Articles

Large Eddy Simulation of Transient Flow and Inclusions Transport in Continuous Casting Mold under Different Electromagnetic Brakes

A mathematical model has been developed to analyze transient fluid flow and inclusions transport in a slab continuous casting mold, considering the effects of electromagnetic brake (EMBr) arrangement and magnetic field strength. Transient flow of molten steel in the mold is calculated by using the large eddy simulation. The electromagnetic force is incorporated into the Navier–Stokes equation. The transport of inclusion inside the mold is calculated using the Lagrangian approach based on the transient flow field. The predicted results of this model are compared with the measurements of the ultrasonic testing of the rolled steel plates and the water model experiments. The transient asymmetrical flow pattern and inclusion transport inside the mold exhibits satisfactory agreement with the corresponding measurements. With electromagnetic brake effect, the velocities around the braking region are significantly suppressed, and the recirculating flow in the lower part drops and tends to develop a plug-like flow. The EMBr arrangement has an insignificant effect on the overall removal fraction of inclusions, especially for larger inclusions. The inclusion removal rate for the flow-control mold (FCM arrangement) reduces instead compared with no EMBr, especially for smaller inclusions.

Effect of M-EMS on in-mould transient flow during continuous casting

Electromagnetic braking (EMB) and electromagnetic stirring (EMS) are widely used to increase the efficiency in continuous casting process of steel. In particular, in-mould applications (M-EMS) allow decreasing the free surface fluctuation, controlling the velocity field and decreasing the turbulence of the flow. Since laboratory-scale tests are not fully representative of the process and industrial measurements are both expensive and difficult to carry out, numerical simulation is a strong tool to study and optimize these electromagnetic applications in steel industry. These simulations cannot fully model the process because the problem results to be strongly multiphysical and the simulation of all the phenomena involved would lead to huge computational costs, which is one of the main limits in the current situation. For this reason, this work aims at starting searching a coupling algorithm which could guarantee both computational efficiency and accuracy of the final results.

RANCANG BANGUN EXTERNAL ELECTROMAGNETIC RETARDERS SYSTEM PADA MOTOR 1 PHASA

Bima Dicky Anugrah Dewantara, Saiful Manan, in this paper explain that Electromagnetic retarders are generally known as electromagnetic inhibitors or brakes, the braking system eliminates most braking mechanics, thereby reducing conventional braking systems. Safety requirements and safety systems are developed and become a focal point of an equipment. Electromagnetic brakes are a safety component with a control system that is easy to control. With this electromagnetic brake, it will reduce maintenance costs, because it only requires a factor of electricity to be able to move it. The braking system uses electromagnetic forces to slow down a movement, which is generally a shaft motion. A dish with non-ferromagnetic metal material is attached to a rotating shaft. The disk is flanked by the side of the stator in the form of an electromagnetic coil system that can generate a magnetic field from electricity. Electric current generates a magnetic field in the coil. And the metal plate that cuts the magnetic field will cause eddy currents on the disk itself. This eddy current will generate a magnetic field whose direction is opposite to the previous magnetic field, thus inhibiting the rotary motion of the shaft. In designing, experimenting and making an External Electromagnetic Retarders System Design on 1 Phase Motor, use the NE 555 IC as the control duty cycle. So that the relationship between braking current and braking time is inversely proportional if the higher the current, the shorter the time it takes for the rotor to stop. And the relationship between braking current and motor current is directly proportional, by increasing the braking current will increase the load on the motor causing the motor current to increase. Keywords: Electromagnetic Retarders, Electromagnetic Brakes, Eddy Flow EffectReferencesTipler, P. 2008. Physics for Scientist volume 2. New York : WH Freeman and Company..Ishaq, M. 2007. Fisika Dasar Elektisitas dan Magnetisme. Yogyakarta: Graha Ilmu.Millman, Halkias, M.Barmawi, dan M.O.Tjia. 1971. Integrated Electronics:Analog and Digital Circuits and Systems. Jakarta : Erlangga.Ramdhani, Mohamad. 2008. Rangkaian Listrik. Jakarta : Erlangga.Bishop, Owen. 2004. Dasar-Dasar Elektronika. Jakarta : Erlangga.Halliday, David. Robert Resnick. 1978. Fisika Jilid II Edisi Ketiga. Jakarta : Erlangga

Electromagnetic braking revisited with a magnetic point dipole model

A theoretical model is developed to predict the trajectory of magnetized spheres falling through a copper pipe. The derive magnetic point dipole model agrees well with the experimental trajectories for NdFeB spherical magnets of varying diameter, which are embedded inside 3D printed shells with fixed outer dimensions. This demonstration of electrodynamic phenomena and Lenz's law serves as a good laboratory exercise for physics, electromagnetics, and dynamics classes at the undergraduate level.

Hybrid Control Method of the Integrated System of Electromagnetic and Friction Braking of Car

Hybrid Control Method of the Integrated System of Electromagnetic and Friction Braking of Car

High-Agility, Miniaturized Attitude Control Sensors and Actuators in an All-in-one Module

A three-axis attitude control function module was assembled into a highly integrated cubic package (103 cm3 dimension: 1U-sized). The key feature of the cubic module is its high-agility functionality, which is realized by a novel, compact electromagnetic braking mechanism combined with a ferromagnetic wheel. In this study, the proposed concept is compared with existing 1-axis wheel assemblies and the conventional CMG scheme in terms of momentum storage per mass/volume, maneuvering speed, and compactness. A prototype of the module was manufactured to demonstrate this innovative concept.

Brezmrežni model elektromagnetnega zaviranja pri kontinuiranem ulivanju jekla

Brezmrežni model elektromagnetnega zaviranja pri kontinuiranem ulivanju jekla

Design of an Electromagnetic Servo Brake with ABS Function

The focus of this paper is to show a novel electromagnetic servo brake with ABS function. This electro-mechanical device is designed to be installed in mid-range commercial vehicles, and its operation is performed by the battery of the vehicle itself. A control system based on a linear controller was designed to regulate the electric current used by the servo brake. The device designed was constructed and experimentally validated using a test bench. The good agreement obtained from the experiments suggests that the servo brake with ABS function designed could be used in mid-range commercial vehicles in order to reduce the speed of the wheels while simultaneously preventing the wheels from locking safely.

Braking of tearing mode rotation by ferromagnetic conducting walls in tokamaks

An in-depth investigation of the braking of tearing mode rotation in tokamak plasmas via eddy currents induced in external ferromagnetic conducting structures is performed. In general, there is a “forbidden band” of tearing mode rotation frequencies that separates a branch of high-frequency solutions from a branch of low-frequency solutions. When a high-frequency solution crosses the upper boundary of the forbidden band, there is a bifurcation to a low-frequency solution, and vice versa. The bifurcation thresholds predicted by simple torque-balance theory (which takes into account the electromagnetic braking torque acting on the plasma, as well as the plasma viscous restoring torque, but neglects plasma inertia) are found to be essentially the same as those predicted by more complicated time-dependent mode braking theory (which takes inertia into account). Significant ferromagnetism causes otherwise electromagnetically thin conducting structures to become electromagnetically thick and also markedly decreases the critical tearing mode amplitude above which the mode “locks” to the conducting structures (i.e., the high-frequency to low-frequency bifurcation is triggered). On the other hand, if the ferromagnetism becomes too large, then the forbidden band of mode rotation frequencies is suppressed, and the mode frequency consequently varies smoothly and reversibly with the mode amplitude.

Design and evaluation of robot patient for nursing skill training in patient transfer

We developed a robot patient for patient transfer training for simulating a patient’s performance during patient transfer and for enabling nurses to practice their nursing skills on it. To realize the robot patient, we focused on addressing the problems of designing its limb actions to enable it to respond to nurses’ operations. RC servos and electromagnetic brakes were installed in the joints to enable the robot to simulate a patient’s limb actions, such as embracing and remaining standing. To enable the robot to automatically respond to nurses’ operations, an identification method for these operations was developed that used voice commands and the features of the limbs’ posture measured by angle sensors installed in the robot’s joints. The robot patient’s performance was examined by a control test in which four experienced nursing teachers performed patient transfer with the robot patient and a human-simulated patient. The results revealed that the robot patient could successfully simulate the actions of a patient’s limbs according to the nursing teachers’ operations and that it is suitable for nursing skill training.

Effect of Electromagnetic Brake on Decreasing Unbalanced Flow in Mold

In order to clarify the mechanism of suppression of unbalanced flow in the mold under high throughput conditions in continuous casting, the effect of using an electromagnetic brake on decreasing molten steel momentum and suppressing unbalanced flow in the mold was investigated. (1) The measured value of the effect of the electromagnetic brake on decreasing molten steel momentum was consistent with the calculated value. Molten steel momentum could be reduced by more than 50% when the Stuart number was more than 3. 5. (2) Increased mold level fluctuations caused by unbalanced flow in the mold are suppressed by applying the optimum magnetic flux density with an electromagnetic brake, even under high throughput conditions.

CFD of the MHD Mold Flow by Means of Hybrid LES/RANS Turbulence Modeling

AbstractIn the last decades, electromagnetic braking (EMBr) systems become a powerful tool to dampen possible jet oscillations in the continuous casting mold. Further studies showed that if a EMBr is not positioned correctly, it can induce flow oscillations. Hence, the design of these braking systems can be promoted by adequate CFD simulations. In most cases, unsteady RANS simulations (URANS) are sufficient to resolve low-frequency, large-scale oscillations of these MHD flows. Alternatively, Large Eddy Simulations (LES) may also resolve important details of the turbulence. However, since they require much finer computational grids, the computational costs are much higher. A bridge between both approaches are hybrid methods like the Scale Adaptive Simulation (SAS). In this study, we compare the performance of SAS with URANS and LES. Results are validated in detail by comparison with data from a Ruler-EMBr model experiment.

Control of Slag-Dragging Effects at the Metal–Slag Interface through Electromagnetic Brake in a Slab Mold

AbstractTurbulent flow when steel is delivered through a nozzle in a slab mold induces dragging forces at the metal–slag interface that entrain slag droplets into the metal bulk. These dragging effects are discontinuous and correspond to the velocity fluctuations of turbulence at that interface which themselves, are dependent on nozzle immersion, nozzle design, mold width and casting speed. Slag viscosity and density, metal viscosity and slag layer thickness are employed to estimate that critical velocity which is embodied in a critical capillary number for some established mold operating conditions. This approach permits the link between all operating variables including flux chemistry and nozzle design with the interface instability. A relationship between the capillary number and the magnetic field strength used to brake the liquid steel is established which is used to assure the interface stability for any operating condition and flux chemistry.

Effect of Single-Ruler Electromagnetic Braking (EMBr) Location on Transient Flow in Continuous Casting

AbstractUltrasonic Doppler velocimetry measurements and large eddy simulations were conducted on a laboratory-scale physical model of a steel continuous slab caster with a low-melting alloy, both with and without an applied single-ruler magnetic field in one of two different vertical orientations. The computational model agreed very closely with the measurements in all respects, including time-averaged flow, velocity profiles, and transient velocity histories at specific locations. The magnetic field altered both the classic double-roll flow pattern and the flow stability. Lowering the magnetic field below the nozzle caused steeper downward jet angles, lower surface velocities, lower turbulent kinetic energy at the surface, and better flow stability, especially toward the surface, and at higher frequencies. The experimental and computational results both show that the electromagnetic field should not be placed with its maximum directly across the nozzle ports, where it may aggravate unstable flow.

Electric Multi-Module Catapult Dynamics

Electric catapults can be used for automatic information storage in radioactive environment. Dynamics of a transport system with the potential of route flexibility was investigated. This system is made up of stand-alone modules, therefore further expansion is possible. Modules consist of mechanical part (rails for the cart), electrical part (inductor of a linear induction motor (LIM) and electromagnetic brake) and electronic part (thyristor commutator). Cargo cart is mounted on the LIM’s secondary unit that can be catapulted from any station (module) to another. First LIM’s inductor starts the secondary, ejects it out of primary’s range. Inertia of the cart allows it to reach the next station which in turn can either accelerate it or stop it. Position detectors (Hall effect sensors) are used for estimating cart movement. Electromagnetic brakes are used as dynamic braking is not effective in this case. A computer model was designed and various operating modes are simulated (upon non-zero initial conditions).

Evaluation of Defect Distribution in Continuously-Cast Slabs by Using Ultrasonic Defect Detection System and Effect of Electromagnetic Brake on Decreasing Unbalanced Flow in Mold

In order to clarify the suppression mechanism of an unbalanced flow in the continuous casting mold under high molten steel throughput conditions, the relationship between the unbalanced flow and the distribution of defects entrapped on the solidified shell was measured by ultrasonic defect detection. The relationship between the unbalanced flow and the defect distribution in the mold with an electromagnetic brake was also investigated. The main results are summarized as follows.(1) By using a new ultrasonic defect detection system, accurate measurement of defects was achieved for the defects’ diameter of more than 0.6 mm in the range 2–10 mm from surface.(2) The effect of the electromagnetic brake on decreasing molten steel momentum was measured. The measured value was consistent with the calculated value. Molten steel momentum could be reduced by more than 50% when the Stuart number (N) was more than 3.5 under molten steel throughput conditions of 4.7 and 5.3 ton/min.(3) The position of entrapped defects on the solidified shell in the mold was influenced by the molten steel throughput condition and the magnetic flux density of the electromagnetic brake.

Electromagnetic Braking of Natural Convection during Ohno Continuous Casting of an Industrial Aluminum Alloy

With the purpose of obtaining compositionally uniform ingots during Ohno continuous casting of a dilute industrial aluminum alloy through eliminating segregation due to convection, a magnetic field strength required to damp natural convection and suppress macrosegregation was numerically determined. This was achieved by solving conservation equations of continuity, momentum, energy and Maxwell’s equations in order to predict the magnetic field effects on flow field (determining macrosegregation). The electromagnetic field was applied orthogonally to the natural convection flow. Through this approach, the optimum magnetic field strength required to damp natural convection and establish diffusion controlled solute transport of the alloy during solidification was established.

Nonlinear Coupling Characteristics Analysis of Integrated System of Electromagnetic Brake and Frictional Brake of Car

Since theoretical guidance is lacking in the design and control of the integrated system of electromagnetic brake and frictional brake, this paper aims to solve this problem and explores the nonlinear coupling characteristics and dynamic characteristics of the integrated system of electromagnetic brake and frictional brake. This paper uses the power bond graph method to establish nonlinear coupling mathematical model of the integrated system of electromagnetic brake and frictional brake and conducts the contrastive analysis on the dynamic characteristics based on this mathematical model. Meanwhile, the accuracy of the nonlinear coupling mathematical model proposed above is verified on the hardware in the loop simulation platform, and nonlinear coupling characteristics of the integrated system are also analyzed through experiments.

Design and Analysis of a Regenerative Electromagnetic Brake

In this paper, a regenerative electromagnetic brake, which has the same structure as conventional electromagnetic brakes and the same principle as self-excited induction generators, is introduced, and a miniature model is designed. The most important part of the design stage is to choose proper equivalent circuit parameters for self-excitation within a given operating speed range. This paper describes a 3-D map, called a CN-map, that consists of the rotating speed, capacitance, and stator resistance to verify the possibility of self-excitation during the design stage. A miniature model is designed using the map, and the experimental results obtained with the miniature model confirm the feasibility of the design process.

Air-Gap Effect on Single Axis Vibration of Electromagnetic Braking Using Eddy Current on Bearing Cage

An electromagnetic braking system using eddy current experiment was conducted to study the behaviour of the system in terms of vibration. Brake disc used which is Al6061 has a displacement in z-axis direction which occurred because of the repulsive force generated on both sides of the disc as drag force from electromagnetic braking. This study aims to analyze the vibration behaviour when braking occurred in different initial speeds of DC motor and different air-gap cases. Smaller air-gap will produce high braking torque due to the increasing of magnetic field density. The higher the force generated, the vibration of the disc may illustrates different behaviour of the vibration in the structure. Test rig was developed using sensor of accelerometer and data acquisition of NI-DAQ with the use of Dasylab for the measurement and instrumentation purposes. Findings shows that the electromagnetic braking force generated in smaller air-gap between electromagnetic poles and rotating conductive disc during the braking using eddy current has damped the vibration occur in the structure of bearing cage.