Non-uniform Distribution of Magnetic Fluid in Multistage Magnetic Fluid Seals

Wang Zhongzhong,Li Decai,Zhou Jing 한국자기학회 2017 Journal of Magnetics Vol.22 No.2

Magnetic fluid, a new type of magnetic material, is a colloidal liquid constituted of nano-scale ferromagnetic particles suspended in carrier fluid. Magnetic fluid sealing is one of the most successful applications of magnetic fluid. As a new type of seal offering the advantages of no leakage, long life and high reliability, the magnetic fluid seal has been widely utilized under vacuum- and low-pressure-differential conditions. In practical applications, for improved pressure capacity, a multistage sealing structure is always used. However, in engineering applications, a uniform distribution of magnetic fluid under each tooth often cannot be achieved, which problem weakens the overall pressure capacity of the seals. In order to improve the pressure capacity of magnetic fluid seals and broaden their applications, the present study theoretically and experimentally analyzed the degree of non-uniform distribution of multistage magnetic fluid seals. A mathematical model reflecting the relationship between the pressure capacity and the distribution of magnetic fluid under a single tooth was constructed, and a formula showing the relationship between the volume of magnetic fluid and its contact width with the shaft was derived. Furthermore, the relationship of magnetic fluid volume to capacity was analyzed. Thereby, the causes of non-uniform distribution could be verified: injection of magnetic fluid; the assembly of magnetic fluid seals; the change of magnetic fluid silhouette under pressure loading; the magnetic fluid sealing mechanism of pressure transmission, and seal failure. In consideration of these causes, methods to improve the pressure capacity of magnetic fluid seals was devised (and is herein proposed).

여러가지 자기장 배치 기법에 따른 자성유체 속도 및 압력 분포에 관한 수치해석적 연구

송준호(Joon-Ho Song),이육형(Yuk-Hyung Lee),배형섭(Hyung-Sub Bae) 한국기계가공학회 2008 한국기계가공학회지 Vol.7 No.2

In this paper, we analyzed the dynamic behavior of magnetic fluid in a circular pipe with multiple permanent magnets. Magnetic fluid react on magnetic field against the normal fluid. In other words, magnetic fluid flow has the electromagnetism and fluid mechanics. So magnetic fluids has studied about the fluids properties and experiment. In this paper we studied the magnetic fluids velocity and pressure distribution for the novel type actuator. Because the velocity and pressure distribution is the important element of the magnetic fluids flow. First, we analyzed the Maxwell equation for the multiple permanent magnet and then concluded the governing equations for the magnetic fluid flow using the equation of Navier-Stokes. And, we simulated the dynamic behavior of magnetic fluid flow using the FEM(Finite Element Method). And we illustrated the relation between magnetic field and dynamic behavior of magnetic fluid flow.

Analysis on Seal Capacity of Magnetic Fluid Seal Using Ring Magnet

Jiawei Liu,Decai Li 한국자기학회 2022 Journal of Magnetics Vol.27 No.1

Magnetic fluid seal is one of the most mature applications of magnetic fluid. When the shaft has a large radial runout, the classical pole piece is easily damaged. Due to its small size, the commonly used pole piece structure harbors problems like poor seal performance under a large gap and poor processability. By exploring the distribution law of the magnetic field on the magnet’s surface, we provided theoretical support for the magnetic fluid seal using axially-magnetized ring magnets. New structures for the magnetic fluid seal using axially-magnetized slotted ring magnets and the magnetic fluid seal using radially-magnetized ring magnets were proposed. Then, comparisons were made between the classical magnetic fluid seal and the magnetic fluid seal using ring magnets. The results revealed that the magnetic fluid seal using axially-magnetized slotted ring magnets and the magnetic fluid seal using radially-magnetized ring magnets exhibited a certain seal capacity, which could replace the classical magnetic fluid seal structure.

Theoretical Analysis and Experimental Study on the Influence of Magnet Structure on Sealing Capacity of Magnetic Fluid Seal

Yanhong Cheng,Zhongzhong Wang,Decai Li 한국자기학회 2019 Journal of Magnetics Vol.24 No.3

The Magnetic fluid is a new type of magnetic material. It is a colloidal liquid made of nanoscale ferromagnetic particles suspended in a carrier fluid. Magnetic fluid sealing is one of the most successful applications of the magnetic fluid. As a new type of seal with the advantages of no leakage, long life and high reliability, magnetic fluid seal has been widely used under vacuum and low pressure differential condition. Two types of permanent magnets, the annular permanent magnets and the cylindrical magnets, are usually used in magnetic fluid seals in engineering. However, the influence of permanent magnet structure on sealing capacity was not clear, hence a new experimental setup was designed in order to study the influence of permanent magnet structure on sealing capacity. The annular permanent magnets and the cylindrical magnets were used as the magnetic source of the experimental setup in a series of tests respectively. The relationship between the sealing capacity of magnetic fluid seal and the end-face area, axial length of the magnet was analyzed by the electromagnetism theories and theoretical derivation. The result of the experiments shows that the sealing capability grows with the end-face area of the magnet, and the growth rate becomes much slower when magnet end-face area attains a certain value; the reluctance of pole pieces and shaft can’t be ignored when magnetic field attains a certain value; the modified theoretical formula had a good match to the measured values when the end-face area of the magnet is small enough to ignore the reluctance of pole pieces and shaft.

A study of the torque characteristics of small disk brake using magnetic fluid

Bae, Hyung-Sub,Park, Myeong-Kwan 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.2

A magnetic fluid simultaneously has hydrodynamic and electromagnetic properties because its characteristics depend on whether a magnetic field is applied or not. The studies conducted so far on actuators that use a magnetic fluid are insufficient. A magnetic fluid has an added advantage in that it can be applied to small or micro systems because of its nanoscale particle size. Therefore, this research investigated the braking characteristics of a small disk brake that used a magnetic fluid. First, magnetostatic analysis of the magnetic field produced by a permanent magnet was conducted, and then, the pressure distribution in the magnetic acted upon by the magnetic body force from the permanent magnet was analyzed using the governing equations of a magnetic fluid. So, in this research, the torque characteristic of small disk brake by a magnetic body force was studied through the relation between the magnetic field intensity and rotational disk velocity. In addition, the torque characteristics of the brake due to a magnetization of the magnetic fluid were confirmed experimentally.

A Study of Magnetic Fluid Seals for Blood Sealing

Jun TOMIOKA,Akira FUKAISHI,Takashi OHBA 한국트라이볼로지학회 2002 한국트라이볼로지학회 학술대회 Vol.2002 No.10

Magnetic fluid seals are used in a wide variety of gas and dust sealing applications. However, it is difficult to seal for liquid because of its characteristic. This study will be a basic guide for a magnetic fluid seal for liquid, especially for blood to be practically used in medical instruments such as rotary blood pumps by clarifying its seal properties. Sealing pressure test, durability test, and hemolysis test have been conducted for this seal. In this study, magnetic fluid, sealing fluid, eccentricity ratio, revolution speed were selected as parameters. As results of the tests, it has been found that the properties of magnetic fluid seal depend on the solvent and the saturation magnetization of magnetic fluid. Therefore, the selection of magnetic fluid is important for this seal. It also has been found that eccentricity ratio of the shaft caused harmful effect for seal propertles. In conclusion, it has been showed that magnetic fluid seals could be possibly used in medical instruments such as blood pumps when blood come in contact with magnetic fluids.

액체 저장 용기 내에서의 자성유체 슬로싱 현상에 관한 해석적 연구

배형섭(H. S. Bae),김상열(S. Y. Kim),박명관(M. K. Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

In this paper, we analyzed numerically the dynamic behavior of magnetic fluid in a storage container from the magnetic field by a permanent magnet. Magnetic fluid react on magnetic field against the normal fluid. In other words, magnetic fluid sloshing problem has the electromagnetism and fluid mechanics. First, we analyzed the Maxwell equation for the permanent magnet and then concluded the governing equations for the magnetic fluid sloshing using the equation of Navier-Stokes and motion of storage container. And, we simulated the dynamic behavior of magnetic fluid and storage motion using the ALE(Arbitrary Lagrangian-Eylerian) method. And to conclude, we illustrated the relation between the motion of storage container and dynamic behavior of magnetic fluid.

자성유체의 자기적 거동특성을 이용한 광 스위치에 관한 연구

최범규,오재근,김도형,송관민 한국센서학회 2005 센서학회지 Vol.14 No.1

This paper presents the development of the optical switch using magnetic behavior of magnetic fluids, which is expected to be used broadly in high-speed information communication. The magnetic fluids for switching an incident light, have the magnetic characteristics of magnetic materials and fluidity of liquids, simultaneously. The relations are derived between the intensity of magnetic field and the angle of optical fiber which is bent by a behavior of magnetic fluid when the magnetic field is applied. When optical switch is implemented by the movement of liquid using magnetic fluid, the existing problem of durability for optical switch will be improved. Thus, this study shows the feasibility of the application for the optical switches using magnetic fluids.

Application of Amorphous Nanoparticle Fe-B Magnetic Fluid in Wastewater Treatment

Chuncheng Yang,Mengchun Yu,Xiuling Cao,Xiufang Bian 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.9

Amorphous magnetic particles demonstrate excellent comprehensive properties and outstanding characteristics for numerous applications. In this report, magnetic crystalline Fe3O4 and amorphous Fe-B nanoparticles were successfully synthesized and introduced to prepare water-based magnetic fluids. The Fe3O4 and Fe-B particles are homogeneous nanoparticles with an average particle size of 12~15 nm. The shape of Fe-B amorphous nanoparticles is regular. The saturation magnetizations of Fe-B and Fe3O4 particles are 74 emu/g and 69 emu/g. The use of crystalline Fe3O4 magnetic fluid and amorphous Fe-B magnetic fluid in advanced treatment of high concentration organic wastewater was presented. The removal rate of chemical oxygen demand by using the amorphous Fe-B magnetic fluid reached 96%, about 16% higher than that by using the Fe3O4 magnetic fluid. Moreover, compared with Fe3O4 magnetic fluid, the treatment results demonstrate that the decolorizing effect by using the amorphous Fe-B magnetic fluid was 20% higher. It has been found that the nano-size Fe-B particles in magnetic fluid with amorphous structure led to high efficiency of wastewater treatment due to the catalytic activity.

자성유체 구동형 혈액펌프에 관한 기초연구

김동욱 순천향대학교 부설 산업기술연구소 2005 순천향 산업기술연구소논문집 Vol.11 No.2

A variety of actuators have been studied for an implantable artificial heart. They, all, however, have common drawbacks in complicated energy conversion mechanism and the use of bearings. A ferrofluidic actuator directly drives magnetic fluids simply by applying a magnetic field to these fluids ; it requires no bearings. The feasibility was studied. An array of two poles of ring solenoids with a gap of 10㎜ was mounted near the acrylic tube (7.4 ㎜D). A rubber sac (volume : 2㎖) was connected to both ends of the acrylic tube, The sacs were encased in a rigid chamber that had inlet and outlet ports. The acrylic tube and the rubber sacs were filled with water and the magnetic fluid and the iron cylinder were immersed in the water. Two experiments were conducted: 1) the magnetic fluid only was used and 2) the magnetic fluid and the iron cylinder (7.1㎜D and 27.8㎖) were used. A flow of 30㎖/min was obtained in the experiment 1 at 140 beats/min and 180㎖min in the experiment 2 at 240 beats/min The maximum driving pressure was 13㎜Hg in the experiment 1 and 300㎜Hg in the experiment 2. The combination of the magnetic fluid and the iron cylinder was used as a substitute for magnetic fluids with high magnetization. The substitute could eject a flow of 80.9% of the maximum value. A magnetic fluid-driven blood pump could be feasible if the magnetic fluid with high magnetization (1.5 times greater than the current value) is developed