• Title/Summary/Keyword: 전기유동유체

Search Result 150, Processing Time 0.029 seconds

Electrohydrodynamic Flow around a Circular-Cylindrical Rod Submerged in a Dielectric Liquid (비전도성 액체에서의 실린더 막대 주변에 생기는 전기동역학적 유체흐름)

  • Park, Hyun-Jin;Ryu, Jae-Chun;Kang, Kwan-Hyoung
    • 한국가시화정보학회:학술대회논문집
    • /
    • 2007.11a
    • /
    • pp.51-54
    • /
    • 2007
  • The induced-charge electroosmosis (ICEO) is a kind of electroosmotic flow which is generated by the electrical charge induced by an externally-applied electric field. That kind of electrokinetic phenomenon provides a nonmechanical technique to handle microscale flows and particles. In this work, we report that the ICEO-like flow is observed around two kinds of circular-cylindrical rod submerged in a dielectric liquid. The conductivity of the solution is varied by adding a surfactant. The flow field is visualized by the PIV method, and average flow speed shows a remarkable dependence on electrical input frequency. Interestingly, the characteristics of the flow are quite different from the conventional ICEO with respect to the flow direction and the locations of center of vortices.

  • PDF

Study on Flow Characteristics of Electro-Rheological Fluids with Electric Field Control (전기장으로 제어되는 ER유체의 유동특성에 관한 연구)

  • Yun Shin-Il;Jang Sung-Cheol;Lee Hae-Soo
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.14 no.5
    • /
    • pp.49-54
    • /
    • 2005
  • An experimental Investigation was performed to study the characteristics of Electro-Rheological fluid flow in a horizontal rectangular tube with or without D.C electric field control. First, the microscopic behavior of the ER suspension structure between rectangular tube brass electrodes for the stationary ER nut(i and flow of the ER fluid was investigated by flow visualization. The flow of the ER fluid between fluid rectangular tube was solved experimental using the constitutive equation for a Bingham fluid. ER fluid is made silicon oil mixed with $0.2wt\%$ starch having hydrous particles. Velocity distributions of the ER fluids were obtained by particle image velocimetry measuring those of the clusters using an image processing technique.

Simulation of Direct Methanol Fuel Cells Employing Computational Fluid Dynamics(CFD) (유체 전산모사를 통한 직접 메탄올 연료전지의 시뮬레이션)

  • Kim, Young-Jin;Lee, Tae-Hee;Oh, In-Hwan;Hong, Seong-An;Kim, Huk-Nyun;Ha, Heung-Yong
    • Journal of the Korean Electrochemical Society
    • /
    • v.6 no.1
    • /
    • pp.28-35
    • /
    • 2003
  • A numerical analysis of electrochemical reaction and dynamics of the fluid flow in the channels of a DMFC separator was carried out by using a commercial Computational Fluid Dynamics(CFD) code fluent(ver.6.0). From the simulation work, many valuable informations were obtained in terms of distributions of velocity, pressure, temperature, concentration and current density over the flow field. And it was possible to optimize the flow field structure by using the simulation results. The simulation work using the Cm code was found very helpful in analysing the phenomena occurring in the fuel cell and optimizing the structures of electrodes and flow field.

Numerical Modeling of Hydrazine-Fueled Arcjet Thruster (하이드라진(N2H4) 아크젯 추력기의 수치적 모델링)

  • Shin, Jae-Ryul;Lee, Dae-Sung;Oh, Se-Jong;Choi, J.-Y.
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.36 no.9
    • /
    • pp.907-915
    • /
    • 2008
  • The computational fluid dynamic analysis has been conducted for the thermo-chemical flow field in an arcjet thruster with mono-propellant Hydrazine (N2H4) as a working fluid. The Reynolds Averaged Navier-Stokes (RANS) equations are modified to analyze compressible flows with the thermal radiation and electric field. the Maxwell equation, which is loosely coupled with the fluid dynamic equations through the Ohm heating and Lorentz forces, is adopted to analyze the electric field induced by the electric arc. The chemical reactions of Hydrazine were assumed to be infinitely fast due to the high temperature field inside the arcjet thruster. The chemical and the thermal radiation models for the nitrogen-hydrogen mixture and optical thick media respectively, were incorporated with the fluid dynamic equations. The results show that performance indices of the arcjet thruster with 1kW arc heating are improved by amount of 180% in thrust and 200% in specific impulse more than frozen flow. In addition thermo-physical process inside the arcjet thruster is understood from the flow field results.

Vibration Characteristics and Control of Smart Cantilever Beams Containing an Electro-Rheological Fluid An Experimental Investigation (전기 유동유체를 함유하는 지능외팔보의 진동특성 및 제어 실험적 고찰)

  • Choi, Seung-Bok;Park, Yong-Kun;Suh, Moon-Suk
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.17 no.7 s.94
    • /
    • pp.1649-1657
    • /
    • 1993
  • This paper reports on a proof-of-concept experimental investigation focused on evaluating the vibration characteristics and control of smart hollow cantilever beams filled with an electro-rheological(ER) fluid. The beams are considered to be of uniform viscoelastic materials and modelled as a viscously-damped harmonic oscillator. Electric field-dependent natural frequencies, loss factors and complex moduli are evaluated and compared among three different beams : two types of different volume fraction of ER fluid and one type of different particle concentration of ER fluid by weight. Modal characteristics of the beams are observed in both the absence and the presence of electric potentials. It is also shown that by constructing active control algorithm the removal of structural resonances and the suppression of tip deflection are obtained. This result provides the feasiblility of ER fluids as an active vibration control element.

Effect of Flow Direction on Temperature Uniformity in Solid Oxide Fuel Cell (고체산화물 연료전지의 유동방향에 따른 온도 균일성 영향)

  • Jeon, Dong Hyup;Shin, Dong-Ryul;Ryu, Kwang-Hyun;Song, Rak-Hyun
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.41 no.10
    • /
    • pp.667-673
    • /
    • 2017
  • We investigated the temperature uniformity in an anode-supported solid oxide fuel cell, using the open source computational fluid dynamics (CFD) toolbox, OpenFOAM. Numerical simulation was performed in three different flow paths, i.e., co-flow, counter-flow, and cross-flow paths. Gas flow in a porous electrode was calculated using effective diffusivity while considering the effect of interconnect rib. A lumped internal resistance model derived from a semi-empirical correlation was implemented for the calculation of electrochemical reaction. The result showed that the counter-flow path displayed the most uniform temperature distribution.

Effect of Particle Aggregation on Dynamic Response of An Electrorheological Fluid in Shear Mode (전단 유동을 하는 전기유변 유체의 동적 응답에 입자 응집이 미치는 영향)

  • Choi, Byung-Ha;Nam, Yun-Joo;Park, Myeong-Kwan
    • Proceedings of the KSME Conference
    • /
    • 2007.05b
    • /
    • pp.2885-2889
    • /
    • 2007
  • In this study, the effect of particle aggregation on dynamic response time of Electrorheological (ER) fluid is investigated. The particle aggregation time is defined as the time interval between the application of the field and the formation of the first chain bridging the two electrodes. The dynamic response times of an ER fluid sheared between two concentric cylinders have been obtained under two different experimental conditions: the one is that the electric field is induced before shearing, and the other is that the electric field is induced after shearing. From the difference between two response times, the particle aggregation times are determined under various electric fields and shear rates. The experimental results show that the aggregation rate is decreased with an increase of shear rate, while electric field has little effect on it. Therefore, it is verified that the hydrodynamic force hinders the formation of chain-like structures.

  • PDF

Transient Response of an Electrorheological Fluid in Shear Flow (전단 유동 하에서 전기유변유체의 과도응답 특성)

  • Choi, Byung-Ha;Nam, Yun-Joo;Park, Myeong-Kwan
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.33 no.6
    • /
    • pp.411-417
    • /
    • 2009
  • The transient shear stress response of an electrorheological fluid is investigated experimentally. The characteristic time constants of an electrorheological fluid sheared between two concentric cylinders were obtained under various electric field strengths and shear rates. Also, two experimental modes are adopted to investigate the effect of the shear flow on the dynamic behavior of the fluid; one is that the electric field is induced before shearing, and the other is the electric field is induced after shearing. From the difference in the response time between two modes, the cluster formation time were obtained. The response times were decreased with the increase of the shear rate, irrelatively of the electric field strength. The cluster formation time were monotonically increased with increase of shear rate, and thereafter, were converged with a certain value.

Investigation of Mechanical Characteristics of ER Fluids for Application in Hydraulic Valve (유압밸브 적용을 위한 ER 유체의 역학적 특성 고찰)

  • 김옥삼;이현창;박우철
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.10 no.4
    • /
    • pp.84-90
    • /
    • 2001
  • The electro-reheoligical(ER) effect refers to the abrupt change in viscosity in certain suspensions on application of an electric field. This paper presents experimental results on material properties of an ER fluids subjected to electrical fatigues. As a first step, two types of EF fluids are made of arabic gum and methyl cellulose(MC) choosing 25% of parti-cle weight-concentration. Following the construction of test mechanism for electrical durability of ER fluid, the dynamic yield shear stress and current density of the ER fluids are experimentally distilled as a function of electric field. The yield shear stress of operated ER fluids are distilled and compared with those of unused ER fluids.

  • PDF

Flow Characteristics of Dispersive ER Fluid Clearance between ER-Valve (ER-Valve 간극내에서 분산계 ER유체의 유동특성)

  • 장성철;염만오;이종두;장성수
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2003.06a
    • /
    • pp.1123-1126
    • /
    • 2003
  • In this research 4 plate type ER-Valves which have same surface but different width and length are designed and an experimental apparatus is constructed. With this experimental apparatus, flow rate and pressure drop of ER fluid flowing in ER-Valve are measured by varying electric field strength of ER-valve, and relation between valve types and pressure drop is also experimented. ER fluid is made silicon oil mixed with 40wt% starch having hydrous particles. The pressure drop according to the strength of electric field by differential pressure gauge in the present ER-Valve was used. This test reviewed experiment for the special changes of ER fluids in the steady flow condition.

  • PDF