• Title/Summary/Keyword: Fluid Effect

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A Study on Vibration Characteristics in Water Tank with Multi-panels (복수 평판으로 이루어진 접수 탱크 구조물의 진동 특성에 관한 연구)

  • Bae, S.Y.
    • Journal of Power System Engineering
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    • v.14 no.6
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    • pp.67-74
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    • 2010
  • Many tanks are installed in ship and marine structures. They are often in contact with inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine and propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tanks. Many authors have studied vibration of cylindrical and rectangular tanks containing fluid. Few research on dynamic interaction among tank walls through fluid are reported in the vibration of rectangular tanks recently. In case of rectangular tanks, structural coupling between adjacent panels and effect of vibration modes of multiple panels on added mass have to be considered. In the previous report, A numerical tool of vibration analysis of a 3-dimensional tank is developed by using finite element method for plates and boundary element method for fluid region. In this paper, the coupling effect between panels of a tank on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region and mode characteristics in accordance with changing breadth of the plates are investigated numerically and discussed.

The Effect of Combined Aggregates on Fluidity of the High Fluid Concrete Containing GGBFS (고로슬래그미분말을 혼입한 고유동콘크리트에서 골재조합이 콘크리트 유동성상에 미치는 영향에 관한 실험 연구)

  • Kim, Jae-Hun;Yoon, Sang-Chun;Jee, Nam-Yong
    • Journal of the Korea Institute of Building Construction
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    • v.3 no.4
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    • pp.79-86
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    • 2003
  • The purpose of study is to offer base data for high fluid concrete mix property, as grasp effect of aggregate to reach much more effect for producing high fluid concrete. For this study, there are three types of combined aggregates, river sand + river aggregate(type A), river sand + crusted aggregate(type B), washed sea sand + crushed aggregate(type C) and take a factor, water-contents, water-binder ratio and S/a. And so, we had following conclusion, resulting application-ability of high fluid mortar by K-slump tester to use a handy consistency measuring instrument. And so, we had following conclusion, resulting application-ability of high fluid concrete by K-slump tester to use a handy consistency measuring instrument. 1) In cafe of regular water binder ratio, high fluid concrete suffered much effect of combined aggregates and water binder ratio. Range of water binder ratio by combined aggregates is w/b 0.4 downward(type A and B), w/b 0.35 downward(type C). 2) Water contents to need for producing high fluid concrete is minimum 170kg/$\textrm{m}^3$ without regard to combined aggregates. 3) The effect of S/a on high fluid concrete by combined aggregates is approximately S/a 50% (type A and B), s/a 50-55% (type C). 4) Consistency measuring of high fluid concrete by K-slump tester is possible and first indication value, high fluid concrete can be produced, is 6~10.5cm.

The Effect of Added Mass of Water and Breath Mode in Fluid-Structure Coupled Vibration Analysis (부가질량 효과와 호흡모드를 고려한 구조-유체연성진동해석)

  • Bae, S.Y.
    • Journal of Power System Engineering
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    • v.9 no.4
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    • pp.71-76
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    • 2005
  • Marine structures are often in contact with inner or outer fluid as stern, ballast and oil tanks. The effect of interaction between fluid and structure has to be taken into consideration when we estimate the dynamic response of the structure appropriately. Fatigue damages can also be sometimes observed in these tanks which seem to be caused by resonance. Thin walled tank structures in ships which are in contact with water and located near engine or propeller where vibration characteristics are strongly affected by the added mass of containing water. Therefore it is essentially important to estimate the added mass effect to predict vibration characteristics of tank structures. But it is difficult to estimate exactly the magnitude of the added mass because this is a fluid-structure interaction problem and is affected by the free surface, vibration modes of structural panels and the depth of water. I have developed a numerical tool of vibration analysis of 3-dimensional tank structure using finite elements for plates and boundary elements for fluid region. In the present study, the effect of added mass of containing water, the effect of structural constraint between panels on the vibration characteristics are investigated numerically and discussed. Especially a natural frequencies by the fluid interaction between 2 panels and a breath mode of the water tank are focused on.

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Vibration Analysis of a Water Tank Structures (접수탱크구조의 진동해석)

  • Bae, S.Y.
    • Journal of Power System Engineering
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    • v.9 no.4
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    • pp.65-70
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    • 2005
  • A liquid storage rectangular tank structures are used in many fields of civil, mechanical and marine engineering. Especially, Ship structures have many tanks in contact with inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tank structures. Many authors have studied vibration of cylindrical and rectangular tanks structures containing fluid. Few research on dynamic interaction among tank walls through fluid are reported in the vibration of rectangular tanks recently. In case of rectangular tanks, structural coupling between adjacent panels and effect of vibration modes of multiple panels on added mass have to be considered. In the present paper, coupling effect between panels of tank structure on added mass of containing fluid, the effect of structural constraint between panels on each vibration mode for fluid region have investigated numerically and experimentally.

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Injection of an Intermediate Fluid into a Rotating Cylindrical Container Filled with Two-layered Fluid

  • Na, Jung-Yul;Hwang, Byong-Jun
    • Journal of the korean society of oceanography
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    • v.31 no.4
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    • pp.173-182
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    • 1996
  • A median-density fluid was injected into the upper layer of a two-layered fluid in a rotating cylindrical container. Several sets of the top and bottom boundary configurations were employed and the flow pattern of each layer including the injected fluid was observed to determine the factors that affect the path of the injected intermediate fluid. The axisymmetric path of the intermediate fluid when the upper layer had a free surface, changed into the asymmetric path with bulged-shape radial spreading whenever either the upper layer or the lower layer had ${\beta}$-effect. The internal Fronds number that controls the shape of the interface turned out to be the most important parameter that determines the radial spreading in terms of location and strength. When the upper and lower layer had the ${\beta}$-effect, convective overturning produced anticyclonic vortices at the frontal edge of the intermediate fluid, and that could enhance the vertical mixing of different density fluids. The intermediate fluid did not produce any topographic effect on the upper-layer motion during its spreading over the interface, since its thickness was very small. However, its anticyclonic motion within the bulged-shape produced a cyclonic motion in the lower layer just beneath the bulge.

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Fluid Film Characteristics between Cylinder Block and Valve Plates in Oil Hydraulic Piston Pumps (유압 피스톤 펌프의 실린더 블록과 밸브 플레이트 사이의 유막 특성)

  • Jung J.Y.;Song K.K.;Oh S.H.;Kim J.K.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.1 no.2
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    • pp.8-14
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    • 2004
  • Abstract: In the oil hydraulic piston pumps the clearance between the valve plate and cylinder block plays an important role for volumetric and overall efficiency. Thus, adequate lubricational fluid film is needed for the interface. In this study, fluid film thickness is measured by a gap sensor and a slip ring under operational conditions to observe the behavior of the lubrication mechanism in detail. To investigate the effect according to the valve plate types in view of the fluid film, three different types were designed. Leakage flow rate and shaft torque were also measured to clarify the effect according to the valve plate types. A broad range of experiments were conducted to provide reasonable data on the effect of fluid film. In this experiments two main parameters were found, of which the one is the discharge pressure and the other is valve plate geometry. As a result, we found that the spherical valve plate could get more stable fluid film thickness, maintain good efficiency for high pressure range than the other types.

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Seismic Analysis of Rectangular Liquid Storage Structures Ssing Fluid Elements (유체요소를 이용한 직사각형 유체 저장구조물의 지진해석)

  • 김영석;김제민;윤정방
    • Journal of Ocean Engineering and Technology
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    • v.6 no.2
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    • pp.46-54
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    • 1992
  • In this paper, behavior of rectangular storage structures under earthquake loadings are investigated. Linear sloshing is assumed in this study. The effect of the wall flexibility is considered. Eulerian and lagrangian approaches are presented. The Eulerian approach is carried out by solving the boundary value problem for the fluid motion. In the lagrangian approach, the fluid as well as the storage structure is modelled by the finite element method. The fluid region is discretized by using fluid elements. The (1 $\times$ 1)-reduced integration is carried out for constructing the stiffness matrices of the fluid elements. Seismic analysis of the coupled system is carried out by the response spectra method. The numerical results show that the fluid forces on the wall obtained by two approaches are in good agreements. By including the effect of the wall flexibility, the forces due to fluid motion can be increased very significantly.

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Natural vibration characteristics of a clamped circular plate in contact with fluid

  • Jhung, Myung Jo;Choi, Young Hwan;Kim, Hho Jung;Jeong, Kyeong Hoon
    • Structural Engineering and Mechanics
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    • v.21 no.2
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    • pp.169-184
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    • 2005
  • This study deals with the free vibration of a circular plate in contact with a fluid; submerged in fluid, beneath fluid or on fluid. An analytical method based on the finite Fourier-Bessel series expansion and Rayleigh-Ritz method is suggested. The proposed method is verified by the finite element analysis using commercial program with a good accuracy. The normalized natural frequencies are obtained in order to estimate the relative added mass effect of fluid on each vibration mode of the plate. Also, the location of plate coupled with fluid and the cases of free and bounded fluid surface are studied for the effect on the vibration characteristics.

A Study of various Working Fluid in the Low Temperature Heat Pipe (저온용(低溫用) 히이트파이프의 작동유체(作動流體)에 관한 연구(硏究))

  • Chang, Young-Suk;Lee, Young-Soo;Seoh, Jeong-Il
    • Solar Energy
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    • v.6 no.2
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    • pp.76-85
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    • 1986
  • The study on the characteristics of heat transfer by various working fluid and wick structure is an important subject in order to design low temperature heat pipe. The purpose of this research was to study the heat transfer characteristics of heat pipe according to various working fluid and wick thickness by ADI method and experimental results. As the results the heat transfer by various working fluid could improve by good heat conductivity of fluid and small ratio t/k. The working fluid could be selected in close vicinity to boiling temperature among fluid properties the value of ratio little influenced heat transfer of heat pipe. In case of distilled water, the response of the effect in heat recovery was more rapidly showed than response of other working fluid. The maximum heat flux increased in proportion to the characteristics of working fluid but the pore and wick permeability among wick characteristic was little effect in the wetting state.

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EFFECT OF MAGNETIC FIELD ON LONGITUDINAL FLUID VELOCITY OF INCOMPRESSIBLE DUSTY FLUID

  • N. JAGANNADHAM;B.K. RATH;D.K. DASH
    • Journal of applied mathematics & informatics
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    • v.41 no.2
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    • pp.401-411
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    • 2023
  • The effects of longitudinal velocity dusty fluid flow in a weak magnetic field are investigated in this paper. An external uniform magnetic field parallel to the flow of dusty fluid influences the flow of dusty fluid. Besides that, the problem under investigation is completely defined in terms of identifying parameters such as longitudinal velocity (u), Hartmann number (M), dust particle interactions β, stock resistance γ, Reynolds number (Re) and magnetic Reynolds number (Rm). While using suitable transformations of resemblance, The governing partial differential equations are transformed into a system of ordinary differential equations. The Hankel Transformation is used to solve these equations numerically. The effects of representing parameters on the fluid phase and particle phase velocity flow are investigated in this analysis. The magnitude of the fluid particle is reduced significantly. The result indicates the magnitude of the particle reduced significantly. Although some of our numerical solutions agree with some of the available results in the literature review, other results differs because of the effect of the introduced magnetic field.