• Title, Summary, Keyword: Magnetic Fluid

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

  • Zhongzhong, Wang;Decai, Li;Jing, Zhou
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.299-305
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    • 2017
  • 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).

Numerical analysis of the magnetic fluid velocity and pressure distribution according to the various magnetic field (여러가지 자기장 배치 기법에 따른 자성유체 속도 및 압력 분포에 관한 수치해석적 연구)

  • Song, Joon-Ho;Lee, Yuk-Hyung;Bae, Hyung-Sub
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.2
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    • pp.31-37
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    • 2008
  • 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.

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Position Control of Capsule Filled with Magnetic Fluid for Targeted Drug Delivery System (지적투약시스템을 위한 자성유체 캡슐의 위치 제어)

  • Ahn Chang-ho;Nam Yun-Joo;Park Myeong-Kwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.8
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    • pp.1166-1173
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    • 2004
  • In this paper, in order to apply magnetic fluid with superparamagnetic property as the substitute of ferromagnetic materials, physical properties of magnetic fluid are investigated. A targeted drug delivery system using a capsule filled magnetic fluid is proposed where a magnetic fluid capsule and cylinders are considered as a drug and vital organs, respectively. The dynamic governing equation of this system first is derived. Fluid viscosity, clearance between a cylinder and a magnetic fluid capsule, and levitation height with respect to different cylinder height are considered as major parameters to evaluate dynamic characteristics of the system. The experiments and simulations for the position control of the magnetic fluid capsule in various cylinders are conducted using PID controller. The results show that magnetic fluid with the superparamagnetic property can be applied to a targeted drug delivery system.

A Study of Magnetic Fluid Seals for Blood Sealing

  • Tomioka, Jun;Fukaishi, Akira;Ohba, Takashi
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.373-374
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    • 2002
  • 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 properties. 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.

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A Study on the Two-dimensional Formation Control of Free Surface of Magnetic Fluid by Electromagnetic Force (전자기력에 의한 자성유체의 2차원 자유표면 형상 제어에 관한 연구)

  • Bae Hyung-Sub;Yang Taek-Joo;Lee Yuk-Hyung;Joo Dong-Woo;Park Myeong-Kwan
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.3
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    • pp.29-37
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    • 2005
  • In this study, the control of the free surface deformation of a magnetic fluid for the change in electromagnetic force is discussed. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. Magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. Thus, the device of a magnetic fluid proposed the complete zero-leakage sealing, oscillator for surface control, boundary layer control, MHD, flow control, flow using magnetic levitation system and surface actuator. This study show the deformation of surface rise due to the intensity of the magnetic field and possibility of two-dimensional control of magnetic fluid through the feedback data of hall sensor.

Design of Magnetic Fluid Linear Pump (자성유체를 이용한 Linear Pump의 설계와 제작)

  • Park, Gwan-Soo;Park, Sang-Ho
    • Proceedings of the KIEE Conference
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    • pp.37-39
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    • 1999
  • In this paper, the magnetic fluid linear pump is designed. Inside the small tube, magnetic fluid is shielded with thin rubber protector. The magnetic fluid activated by traveling pulses of magnetic field drags the water inside the pump. The iterative algorithm for the shape of magnetic fluid is presented by using nonlinear finite element method and Navier-Stokes equations. The computed curvature of fluid under the magnetic field and the gravitational force is agreed well with photograph image. The dimension and electric configurations of the magnetic linear pump are optimized and the results are compared with measurements.

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Experimental study of natural convection for magnetic fluids in annular pipes (이중원관내 자성유체의 자연대류에 관한 실험적 연구)

  • Park, Joung-Woo;Lee, Jun-Hee;Seo, Lee-Soo
    • Proceedings of the KSME Conference
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    • pp.191-195
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    • 2001
  • The applications of magnetic fluid can be normally made by 1) using changes of a property of matter caused by applied magnetic field; 2) preserving magnetic fluid at a certain position or in a magnetic fluid keeping the body in a floating condition; 3) controlling the flow of magnetic fluid by means of magnetic field. However, these are usually made by using their methods together. In this study, the natural convection flow of a magnetic fluid in annular pipes is experimentally analyzed. High temperature is kept constantly inside of a circular pipe of experimental model, on the other hand, low temperature is kept constantly outside of it. In experiments, several cases are carried out in order to clarify the fluence of direction and intensity of magnetic fields on the natural convection of magnetic fluid. Therefore magnetic fields are applied in various intensity and up and down directions by permanent magnets.

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A Study on the Deformation control of Free Surface of Magnetic Fluid (자성유체 자유표면의 형상 제어에 관한 연구)

  • 안창호;김대영;지병걸;이은준;박명관
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.297-300
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    • 2002
  • In this study, the deformation of the free surface motion of a magnetic fluid for the change in electromagnetic force is discussed and carried out theoretically and experimentally on the basis of Rosensweig Ferrohydrodynamic Bernoulli Equation. While applied magnetic fields are induced by 4$\times$4 electromagnet located under the magnetic fluid, the surface of the magnetic fluid is formed the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body farce. In case, magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. thus, the device of a magnetic fluid proposed the surface actuator. The device of surface deformation as well comparison between numerical simulation and experiments as will be presented.

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An Experiment Study of Semi-Active Damper Using Magnetic fluid (자성유체를 이용한 반능동식 댐퍼에 관한 실험적 연구)

  • Hwang, Seung-Sik
    • The KSFM Journal of Fluid Machinery
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    • v.7 no.4
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    • pp.24-31
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    • 2004
  • The aim of this study is to provide fundamental information for the development of Semi-Active Damper Using Magnetic fluid. To achieve the aim, the damping effect of magnetic fluid is investigated by experiments that the diameter of inner circular bar and the input amplitude were varied in the magnetic field generated by the permanent magnet and the electromagnet coil. From the study, the following conclusive remarks can be made. As the diameter of inner circular bar and input amplitude increase, the damping effect is improved. This is explained by the fact that as the contact area between inner circular bar and magnetic fluid increases, the increase of friction lowers kinematic energy. If the magnetic field is generated, the damping effect is improved. This is explained the assumption that as the intensity of magnetic fluid particle increases, there is virtual mass phenomenon.

Loss of Torque on Magnetic Fluid Seals with Rotating-shafts

  • Hu, Jianhui;Zhao, Meng;Wang, Lu;Zou, Jibin;Li, Yong
    • Journal of Magnetics
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    • v.22 no.2
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    • pp.286-290
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    • 2017
  • The effects of loss of torque on magnetic fluid seals with rotating-shafts and the general difficulty of studying magnetic fluid seals are the focus of this work. The mechanism underlying loss of torque on such seals is analyzed using theoretical methods that show that loss of torque can be affected by several factors, including the velocity of the rotating-shaft, the structure of the sealing device, the characteristics of the magnetic field, and the characteristics of the magnetic fluid. In this paper, a model of the loss of torque is established, and the results of finite element analysis and testing and simulations are analyzed. It is concluded that (i) the viscosity of the magnetic fluid increased with the intensity of the magnetic field within a certain range; (ii) when the magnetic fluid was saturated, the increase in loss of torque tended to gradually slow down; and (iii) although the axial active length of the magnetic fluid may decrease with increasing speed of the rotating-shaft, the loss of torque increased because of increasing friction.