Study of micro-plastics separation from sea water with electro-magnetic force

Nomura, Naoki,Mishima, Fumihito,Nishijima, Shigehiro The Korean Society of Superconductivity and Cryoge 2021 한국초전도저온공학회논문지 Vol.23 No.3

The method of removing micro-plastics from sea water has been developed using electro-magnetic force. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. The Lorentz force was generated in simulated sea water and its reaction force was applied to the micro-plastic to control their motion. Lorentz force was generated downward and the reaction force to the plastics was upward. The plastic used in the experiment was polystyrene with a diameter of 6 mm, and the density was 1.07 g/cm³. The polystyrene sphere levitated at the current density of 0.83 A/cm² and the external field of 0.87T. The particle trajectory calculation was also made to design separation system using superconducting magnet.

Study of micro-plastics separation from sea water with electro-magnetic force

Naoki Nomura,Fumihito Mishima,Shigehiro Nishijima 한국초전도저온공학회 2021 초전도와 저온공학 Vol.23 No.3

The method of removing micro-plastics from sea water has been developed using electro-magnetic force. Plastics are difficult to decompose and put a great load on the marine environment. Especially a plastic with a size of 5 mm or less is defined as micro-plastic and are carried by ocean currents over long distances, causing global pollution. These are not easily decomposed in the natural environment. The Lorentz force was generated in simulated sea water and its reaction force was applied to the micro-plastic to control their motion. Lorentz force was generated downward and the reaction force to the plastics was upward. The plastic used in the experiment was polystyrene with a diameter of 6 mm, and the density was 1.07 g/cm3. The polystyrene sphere levitated at the current density of 0.83 A/cm2 and the external field of 0.87T. The particle trajectory calculation was also made to design separation system using superconducting magnet.

Prototype of 6-DOF Magnetically Levitated Stage Based on Single Axis Lorentz force Actuator

Fengqiu Xu,Xianze Xu,Meng Chen 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.5

We present a prototype of 6-DOF magnetically levitated stage based on single axis Lorentz force actuator is capable of positioning down to micron in several millimeter travel range with a simple and compact structure. The implementation of the Lorentz force actuators, instrument modeling, and motion controller of the maglev system are described. With the force-gap relationship of the actuator solved by Gaussian quadrature, 2-demsional (2D) lookup table is employed to store the result for the designing of control system. Based on the force-gap relationship, we choose the suitable stroke of each actuator to develop the stability of the maglev stage. Complete decoupling matrix is analyzed here to establish a decoupled dynamics between resulting six axis motion and eight outputs to the actuators. The design travel volume of the stage is 2mm×2mm×2mm in translation and 80mrad×80mrad×40mrad in rotation. With a constant gain and critical damping PID controller, the resolution of the translation is 2.8um and 4um root mean square in horizontal and vertical direction respectively. Experimental results are presented to illustrate the positioning fluctuations, step responds and multi axis motion. Some comparative tests are taken to highlight the advantage resulted from the accurate force-gap relationship, suitable stroke, and complete decoupling matrix.

Electromagnetic vortex suppression to prevent air core phenomenon for draining of electrically conducting liquids

손종현,이종희,박일석 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6

The air core phenomenon observed during liquid suction or drainage through a narrow drain port can be reproduced artificially by starting the draining after rotating the cylindrical tank containing the liquid. Because the entrainment of gas-phase fluids during pump suction or liquid draining generates a breakdown of the machinery or defects in the product, various studies have been conducted to retard or prevent the air core phenomenon. Instead of utilizing an artificial structure such as a mesh or vane, as applied in previous studies, the present study introduces a new approach in which a magnetic field is applied to the container. First, the magnetic field applied induces an electric current through a reciprocal action with the liquid flow in the container. Next, the induced current and applied magnetic field create a Lorentz force, which is an electromagnetic body force. The Lorentz force helps with the suppression of existing flows. To couple the flow and electromagnetic fields, we solve the Poisson’s equation for the electric potential along with the momentum conservation. As the draining progresses, a volume-of-fluid (VOF) free surface capturing method is applied to track the free surface evolution, including the air core generation. For various Hartmann number (Ha) conditions, the internal velocities, vorticities, and Lorentz forces are comparatively presented. Finally, the effects of suppressing the air core phenomenon through the application of a magnetic field are discussed.

Analytical and empirical studies on the characteristic resistances of no-insulation GdBCO racetrack pancake coil under various operating currents

김광록,최윤혁,D.G. Yang,D.H. Kang,J.H. Kim,김호민,이해근 한국물리학회 2015 Current Applied Physics Vol.15 No.1

This paper presents the effects of the Lorentz force on the electrical behaviors of the no-insulation (NI) GdBCO racetrack pancake (RP) coil without turn-to-turn insulation by performing charging/discharging and sudden-discharging tests. The simulation results of the 2-dimensional finite element method showed that the Lorentz forces were generated towards the center of the winding pack consisting of 60- turn GdBCO CCs, which could enhanced the turn-to-turn contact within the RP coil. The charging/discharging test results indicated that the characteristic resistance (Rc) of the NI RP coil decreased with increasing operating current, which was caused by an increase of the Lorentz force. Further, the results of the sudden-discharging tests exhibited that the Lorentz force was dissipated instantly during the sudden-discharge of the coil, since the operating current immediately decreased to zero. Overall, this study clearly demonstrated that the Lorentz force induced by the operating current exerts the electrical behaviors of an NI RP coil.

Numerical simulation of 2-D laminar flow subjected to the Lorentz force effect in a channel with backward-facing step

Iman Farahbakhsh,Amin Paknejad,Hassan Ghassemi 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.10

This paper presents the numerical solutions of a two-dimensional laminar flow over a backward-facing step in the presence of the Lorentz body force. The Navier-Stokes equations in a vorticity-stream function formulation are numerically solved using a uniform grid mesh of 2001 × 51 points. A second-order central difference approximation is used for spatial derivatives. The solutions progress in time with a fourth-order Runge-Kutta method. The unsteady backward-facing step flow solution is computed for Reynolds numbers 100 to 800. The size and genesis of the recirculating regions are dramatically affected by applying the Lorentz force. The results demonstrate that using an appropriate configuration for applying the Lorentz force can make it an essential tool for controlling the flow in channels with a backward-facing step.

자기부상용 Halbach 자석 배열을 이용한 선형 능동자기 베어링의 최적설계

이학준(Hakjun Lee),안다훈(Dahoon Ahn) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.1

본 논문은 Halbach 자석 배열을 사용하여 새로운 구조의 선형 능동자기 베어링 개발을 제시하고자 하였다. 선형 능동자기 베어링은 자석 간 발생하는 자중 보상 능력과 코일에 전류를 인가함으로서 발생하는 동적 힘을 이용하여 반도체 장비, 가공 장비 등 다양한 산업분야에서 적용되고 있다. 기존의 선형 능동자기 베어링은 크기에 비해 동적 힘이 낮은 문제점이 있다. 따라서 본 논문에서는 기존 보다 높은 동적 힘을 발휘하는 선형 능동자기 베어링을 개발하기 위해 시뮬레이션을 통해 기존 구조를 분석하고 새로운 구조를 제안하였다. 제안된 새로운 구조의 선형 능동 자기베어링을 최적화하기 위해서 모델링 및 최적 설계를 수행하였다. Sequential Quadratic Programming을 사용하여 제안된 선형 능동자기 베어링의 기하학적 설계 변수에 대해 최적의 설계가 수행되었으며, 최적설계 된 선형 능동자기 베어링의 설계성능은 정적 힘 45.063 N, 로렌츠 힘 상수 19.543 N/A 로 기존보다 높은 동적 힘을 발휘하는 것이 확인되었다. This paper presents a new structure for a linear active magnetic bearing using a Halbach magnet array. The proposed magnetic bearing consisted of a Halbach magnet array, center magnet, and single coil. The proposed linear active magnetic bearing has a high dynamic force compared to the previous study. The high dynamic force could be obtained by varying the thickness of a horizontally magnetized magnet. The new structure of Halbach linear active magnetic bearing has a high dynamic force. Therefore, the proposed linear active magnetic bearing increased the bandwidth of the system. Magnetic modeling and optimal design of the new structure of the Halbach linear active magnetic bearing were performed. The optimal design was executed on the geometric parameters of the proposed linear active magnetic bearing using Sequential Quadratic Programming. The proposed linear active magnetic bearing had a static force of 45.06 N and a Lorentz force constant of 19.54 N/A, which is higher than previous research.

Improved design of Lorentz force-type magnetic bearings for magnetically suspended gimballing flywheels

Liu, Qiang,Wang, Qirui,Li, Heng,Peng, Cong,Xu, Kang,Ren, Yuan The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3

A Lorentz force-type magnetic bearing (LFMB) with good linearity is suitable for the high-precision deflection control of a magnetically suspended gimballing flywheel (MSGFW). In this paper, a novel LFMB with improved double magnetic circuits is presented. Inclined magnetization Halbach array permanent magnets (PMs) and trapezoidal PMs are utilized for improving the magnetic flux density. A mathematical model of the magnetic flux density is established based on the equivalent surface current method. To obtain the maximum magnetic flux density, the optimal magnetization angle is calculated, and the dimension parameters are optimized by the sequential quadratic programming method. A maximum magnetic flux density of 0.615 T is obtained, which is 7.9% larger than that of an LFMB with conventional double magnetic circuits. Based on simulation results, LFMB prototype magnetic flux density experiments are carried out. The results show that the magnetic flux density fluctuations of the two LFMB schemes are similar. The maximum magnetic flux density of 0.608 T is increased by 6.7% when compared with that of the LFMB with conventional double magnetic circuits at 0.57 T. The error between the simulation and the experiment is within 5%. This indicates that the LFMB with improved double magnetic circuits is promising when it comes to meet the agile maneuver requirements of the spacecraft.

Numerical and experimental approach to reduce bouncing effect in electromagnetic forming process using cushion plate

노학곤,송우진,강범수,김정 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.8

Electromagnetic forming (EMF) is a high strain rate forming process that uses Lorentz force. In this study, electromagnetic formingwith a rectangular block shape in the center of the forming die was examined to determine the possibility and applicability of EMF. However, the high speed of the process in the absence of a medium between the coil and the workpiece results in bouncing of the workpiece,which may result in poor forming. So, in this study, the use of a cushion plate is proposed as a means of reducing the degree ofbounce in an EMF process. A 3D electromagnetic numerical model using a spiral forming coil was considered. An RLC circuit, coupledwith the spiral coil, was numerically simulated to determine the deformation behavior and design parameters, such as the input currentand the magnetic forces. A cushion plate was used between the forming coil and the sheet to be deformed to reduce the extent of bounce. In the numerical simulation, the sheet was found to be well fitted to the objective die with the cushion plate. The simulation resultsshowed that the extent of bounce was drastically reduced because of the velocity direction of the workpiece and the cushion plate. Theexperiment was performed using 24 kJ to deform Al 1100 with a thickness of 1.27 mm, based on the simulation results. The deformedsheet was well formed, and closely fitted the objective die with a minimum of wrinkling, relative to the results obtained without a cushionplate. As a result, an EMF process with a middle-block die was successfully established both numerically and experimentally to reducethe bouncing.

3-D Numerical Analysis and Design of Electro-magnetic Forming Process with Middle Block Die

Noh, Hak-Gon,Song, Woo-Jin,Kang, Beom-Soo,Kim, Jeong 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.5

The electromagnetic forming process (EMF) is one of the high speed forming processes using the Lorentz force. In this study, numerical simulations were conducted, to set up an EMF process with a middle rectangular block. A 3D electromagnetic numerical model was considered, based on a spiral forming coil. In the numerical simulation, an RLC circuit coupled with the spiral coil was made to consider the design parameters, such as system input current and electromagnetic force. Magnetic fields and current density were described, to consider their values and direction with time passing. Furthermore, plastic deformation behavior was considered at each time step. A 32 kJ EMF machine was set based on the numerical simulation results, to conduct the test. The experiment was performed in 20 kJ, to deform Al 3104 with a thickness of 1.0 mm. The test workpiece was well formed to fit with the die of the forming set. In order to verify the simulation result, the Z-displacement of the final shape was measured by 3D scan, and compared with the Z-displacement of the simulation result. The measured experimental profiles and numerical final shape are in good agreement, when accounting for the sheet deformation.