• Title, Summary, Keyword: 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).

Fluid heating in a nano-scale Poiseuille flow: A non-equilibrium molecular dynamics study

  • Faraji, Fahim;Rajabpour, Ali
    • Current Applied Physics
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    • v.17 no.12
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    • pp.1646-1654
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    • 2017
  • In this paper we develop a non-equilibrium molecular dynamics computer simulation to study the fluid heating in a nano scale Poiseuille flow system and discuss the effects of the fluid-wall interaction strength and wall temperature on the fluid heating. We calculate the fluid temperature distribution, as well as the heat flux from the fluid towards the walls and the interfacial thermal resistance and discuss the variations of the fluid heating caused by the viscous and surface frictions as the fluid-wall interaction strength and wall temperature vary. It is found that as the fluid-wall interactions strengthen, the fluid heating diminishes. In weak interactions, the heat flux from the fluid to the wall is almost independent of the wall temperature while the interfacial thermal resistance decreases with increased wall temperature and the surface friction is the major contribution to the fluid heating; in contrast, in large interactions, both the heat flux and thermal resistance increase with increased wall temperature and the viscous friction is the major contribution to the fluid heating.

Study on the Relationship between Physiology of Humor and Body fluid and Pathology of 'Phlegm-retained fluid' (수액(水液) 및 진액(津液) 생리(生理)와 담음(痰飮) 병리(病理)의 상관관계에 대한 고찰)

  • Lee, Jung Huk;Kim, Byoung Soo
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.31 no.1
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    • pp.1-7
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    • 2017
  • There are two kinds of body fluid metabolism in Traditional Korean Medicine based on 'Internal Classic'("內經"); one is metabolism of body fluid(津液) meaning metabolism of physiological substance, and another is metabolism of humor meaning a metabolic process that excretes waste out of the body. 'Phlegm-retained fluid'(痰飮) is a typical pathological condition caused by abnormal fluid metabolism in Traditional Korean Medicine. As a result of reviewing the literature on 'phlegm-retained fluid'(痰飮), the following facts were found; 'Phlegm-retained fluid'(痰飮) is formed by abnormal state of metabolism of body fluid(津液). In other words, because of the action of various etiologies, qi(氣) and body fluid(津液) metabolism can have abnormal conditions and these metabolic disorders cause formation of 'phlegm-retained fluid'(痰飮). Treatments for 'phlegm-retained fluid'(痰飮) include the following: Eliminating the causes of illness, recovery of metabolism of qi(氣) and body fluid(津液), and functional recovery of pancreas and kidney related to body fluid(津液) metabolism. These treatments are distinguished from promotion of sweating(發汗) and helping urination, the treatments for humor metabolism abnormality.

A Sliding Mode Control for an Engine Mount Using Magneto-Rheological Fluid (MR유체를 이용한 엔진마운트의 슬라이딩모드제어)

  • 이동길;안영공;정석권;양보석
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1144-1149
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    • 2001
  • In this paper, a sliding mode controller of a fluid engine mount using MR (Magneto-Rheological) fluid was discussed When the MR fluid is applied to a fluid mount, resistance of MR fluid can be controlled by electro-magnetic valve installed in the inertia track. Since the rheological property of the MR fluid shows a function of shear rate, the damping characteristics of the mount will be change according to the frequency. Changing an applied magnetic field to the valve changes the property of the mount, such as the resistance of the MR fluid, the notch and the resonant frequencies due to the fluid passing, quantity of the fluid passing, the effective piston area of the volumetric damping and stiffness. Therefore, the fluid mount using MR fluid can be regarded as a variable structure system The sliding mode control known well as a particular type of variable structure control was introduced in this study. The sliding mode control, which has inherent robustness, is also expected to improve the control performance in the engine mount The sliding mode controller for the mount formatted by taking into account the response property with a time constant to MR fluid and the variable mount property. The motion equations of the fluid mount are derived from Newton's law of motion and used in numerical simulation. Numerical simulations illustrate the effectiveness of the sliding mode controller.

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Performance of Squeeze Film Damper Using Magneto-Rheological Fluid (MR유체를 이용한 스퀴즈필름 댐퍼의 응답특성)

  • 안영공;양보석;신동춘;김동조
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.67-70
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    • 2002
  • This paper presents the property of the Squeeze Film Damper (SFD) using Magneto-Rheological fluid (MR fluid). The damping property of a SFD for a flexible rotor system varied according to vibration mode. MR fluid is known as a functional fluid with controllable apparent viscosity of the fluid by applied magnetic field strength. When the MR fluid is applied in the SFD, the SFD using MR fluid can effectively reduce vibrations of the flexible rotor in a wide range of rotating speed by control of the applied magnetic field strength. To investigate in detail the SFD using MR fluid, the SFD to support one mass was constructed and its performance was experimentally investigated in the present study. The damping property of the SFD using MR fluid has viscous damping by Newtonian fluid, but not Coulomb friction by Bingham fluid. Therefore, The system damped by the SFD can be considered as a linear system.

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Study on Vibration Characteristics of Fluid Tank Structure for Ship (유체 탱크 구조물의 접수 진동 특성에 관한 연구)

  • Seo, Myeng-Kab;Seok, Ho-Il;Lee, Chul-Won
    • Special Issue of the Society of Naval Architects of Korea
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    • pp.85-89
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    • 2013
  • In the engine room and the aft body, there are so many fluid tanks such as fresh water tank and oil tank. The vibration analysis for the fluid tank structures has to consider the added mass effect due to the fluid. However, it is known that the result of the fluid tank has the difference according to the boundary condition of the fluid field such as infinite fluid and finite fluid. In this paper, a numerical case study is carried out for the research about the vibration characteristics of the fluid tank with various fluid field. In addition, an experimental study is carried out to verify the validity of the vibration analysis for the fluid tank structure.

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Evaluation of Apparent Viscosity Properties for Electro-Rheological Fluid (ER유체의 겉보기 점도특성 평가에 관한 연구)

  • ;Morishita, Shin
    • Tribology and Lubricants
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    • v.14 no.2
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    • pp.42-48
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    • 1998
  • Electro-Rheological (ER) fluid is a class of functional fluid whose apparent viscosity can be varied by the applied electric field strength. The ER fluid is classified into two types; one is a dispersive fluid and the other is a homogeneous. Dispersive ER fluid is a colloidal suspension of fine semiconducting particles in a dielectric liquid and liquid crystal (LC) is classed as homogeneous type ER fluid. LC has been originally developed for some electronic display devices. Various mechanical components applying ER fluid have been developed, and the their performance typically depends on the characteristics of ER fluid which have generally been evaluated by a rotational viscometer. However, the ER fluid introduced into various mechanical components undergoes not only simple shear flow but press flow or oscillating flow. For the evaluation of ER fluid, the authors developed an reciprocating type viscometer. The amplitude is controlled on 5 mm at the frequency from 50 to 1000 Hz. In the present paper, the performance of several types of ER fluid is evaluated by the reciprocating type viscometer and compared with those evaluated by a rotational viscometer.

Analysis of the concept of body fluid in "Hwangjenaegyeong(黃帝內經)" ($\ll$황제내경(黄帝内经)$\gg$ "진액(津液)" 개념고변(概念考辨))

  • Feng, Gu;Kim, Hyo-Chul
    • Journal of Korean Medical classics
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    • v.23 no.1
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    • pp.11-13
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    • 2010
  • In this article, the concept of body fluid is explained in three aspects: the word meaning of body fluid, the origins of the definitions of the body fluid concept and the connotation and extension of body fluid. Investigating data about the time Hwangjenaegyeong(黃帝內經) was written, the author discovers that the meaning of "Aek(液)" is clear, but there are still questions about the meaning of "Jin(津)". The concept of body fluid derived from observation of life phenomenon and ancient philosophy on the "water". The concept of body fluid should be expressed as that body fluid is a general term for all normal liquids in the body. Within the meridians, as the composition of blood components; outside the meridians, constituting the intrinsic body fluids of various organs and tissues. This is the main part of body fluid, coming from diet, constituting the human body and maintaining human life activities, playing the roles of moistening and nourishing various of organs and tissues of the body. In addition, Interstitial fluid, all kinds of normal liquid secretion and metabolic products, such as sweat, tears, nasal discharge, saliva, slobber, gastric juice, intestinal fluid, urine, joint fluid, latex and so on, both belong to body fluid.

Vibration Analysis of A 3-Dimensional Pipe Conveying Pulsating Fluid Flow (맥동하는 유체를 포함하는 3차원 배관 계의 진동 해석)

  • Seo, Young-Soo;Jeong, Weui-Bong;Yoon, Sang-Don
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.933-938
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    • 2002
  • A pulsation of fluid in a pipe sometimes causes severe vibration of pipe. The inertia, damping and stiffness characteristics of pipe will be changed by the effect of fluid-structure interaction. The velocity and pressure of fluid will impose the force to a bended shape pipe. In this paper, a pipe with fluid flow is modeled by finite element method and the fluid force from pulsation is also modeled by the fluid dynamics. The vibration of pipe conveying pulsating fluid flow can be estimated by taking into consideration of fluid-structure interaction.

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Vibration Analysis of A 3-Dimensional Pipe Conveying Pulsating Fluid Flow (맥동하는 유체를 포함하는 3차원 배관계의 진동해석)

  • Seo, Young-Soo;Jeong, Weui-Bong;Yoon, Sang-Don
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.391.1-391
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    • 2002
  • A pulsation of fluid in a pipe sometimes cause severe vibration of pipe. The inertia, damping and stiffness characteristics of pipe will be changed by the effect of fluid-structure interaction. The velocity and pressure of fluid will impose the force to a bended shape pipe. In this paper, a pipe with fluid flow is modeled by finite element method and the fluid force from pulsation is also modeled by the fluid dynamics. The vibration of pipe conveying pulsating fluid flow can be estimated by taking into considering of fluid-structure interaction.

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