• 제목/요약/키워드: fluid flow velocity

검색결과 1,740건 처리시간 0.047초

Numerical Analysis of Silicon Deposition in CVD Reactor (화학기상 성장법에 의한 실리콘 부착에 관한 수치해석)

  • Kim, In;Baek, Byung-Joon;Yoon, Jeong-Mo;Lee, Cheul-Ro
    • Proceedings of the KSME Conference
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    • 대한기계학회 2000년도 추계학술대회논문집B
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    • pp.359-364
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    • 2000
  • The fluid flow, heat transfer and the local mass fi-action of chemical species in the chemical vapor deposition(CVD) manufacturing process are numerically studied. The deposition of silicon from dilute silane is hydrogen carrier gas in a horizontal CVD reactor is investigated. The effect of inlet carrier gas velocity, mass fraction of silane, susceptor angle on the deposition thickness and uniformity was represented.

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Prediction of MCFC Unit Cell Performance Using 3-D Heat & Fluid Analysis with Electrochemical Reaction (전기화학반응을 포함한 3차원 열$\cdot$유동해석을 통한 용융탄산염 연료전지의 단위 전지 성능해석)

  • Kim Y. R.;Choi D. H.
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2004년도 추계 학술대회논문집
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    • pp.141-144
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    • 2004
  • An analysis procedure for the MCFC channel flow has been developed to predict the fuel cell performance. The channel formed by the uniformly distributed trapezoidal supports is approximated by the porous medium that yields the equivalent pressure drop. The Wavier-Stokes, energy, and species equations are solved to obtain the velocity, temperature and concentration fields for a local current density which is computed from electrochemical correlations. The fuel cell characteristics, such as the temperature, pressure, mole concentration, voltage and current density distributions, are presented and discussed.

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Riser Design Approach for Particle-Circulation-Type Heat Exchangers (입자 순환식 열교환기의 상승관 설계방법)

  • Jun Yong-Du
    • Proceedings of the KSME Conference
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    • 대한기계학회 2002년도 학술대회지
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    • pp.311-312
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    • 2002
  • In this paper a systematic design approach to determine the optimum size (height) of circulating fluidized bed heat exchanger for exhaust gas heat recovery is prososed. Unlike the convensional heat exchangers where the length of the heat exchanger section is not very much emphasized, the vertical length of heat exchanger tube in the case of fluidized bed heat exchangers is important because this length determines the time interval during which particles reside and transfer heat in the heat exchanger section. For particles initial conditions are nearly stationary, accelerating particles motion should be considered rather than simply assuming fully developed condition. A way to estimate optimum tube length at different fluid velocity and particle sizes is suggested based on the required conditioning time for heat transfer from the flue gas to solid particles.

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A Study on the Vortex Generators of Plastic Plate Heat Exchangers (플라스틱 판형 열교환기의 와류발생기에 관한 연구)

  • Oh Yunyoung;Yoo Seongyeon;Ko Sungho
    • Proceedings of the KSME Conference
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    • 대한기계학회 2002년도 학술대회지
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    • pp.107-110
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    • 2002
  • The present study deals with CFD analysis of 'The vortex generators on plastic plate heat exchanger'. When a vortex generator is placed on the heat transfer surface, the flow gets more complex because it entails complicated three-dimensional flows such as separation, reattachment, and recirculation. CFX-5.4, a commercial code utilizing unstructured mesh, has been used as a computational method for solving RANS(Reynolds-Averaged Wavier-Stokes) equations, and the applied turbulence model is $k-{\varepsilon}$ model. In addition, those computational analyses were implemented under various conditions , with or without the vortex generator between two plates, the number, form and the size of vortex generator, and different attack of angle. From the calculated temperature, velocity and pressure distribution, vorticity, wall heat flux and so on under those conditions, this study shows the effect of vortex on heat transfer.

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An Experimental Study on the Spray Characteristics of Internal Mixing Atomizer for Twin Fluid (내부혼합형 2유체 미립화기의 분무 특성에 관한 실험적 연구)

  • Kim, K.C.;Ha, M.H.;NamKung, J.H.;Lee, S.G.;Rho, B.J.;Kang, S.J.
    • Proceedings of the KSME Conference
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    • 대한기계학회 2001년도 추계학술대회논문집B
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    • pp.693-698
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    • 2001
  • An experimental study was carried out with an aerated nozzle. This nozzle was well known that the performance of the atomization is better than other ones even though the supplied air pressure is lower than that of them. The purpose of this investigation is to provide the essential information of the aerated nozzle from the nozzle exit. The experimental work was performed in order to analyze the characteristics of the overall flow field from the nozzle exit. The 2-D PDPA system was used to acquire the data in the concerned region. The characteristics of the mean velocity distribution, half-width, and SMD were mainly analyzed. Also the correlation between turbulent kinetic energy and SMD was described with ALR.

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A Study on the Rheology Characteristics of Magnetic Fluids in a Circular Pipe (원관내 자성유체의 Rheology 특성에 관한 연구)

  • Jeon, Eon-Chan;Park, Joung-Woo;Kim, Tae-Ho;Kim, Soo-Yong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • 제7권2호
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    • pp.38-44
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    • 2008
  • In the present paper, we theoretically analyze the flow of magnetic fluids in a circular pipe with a vertical magnetic field and investigate the magnetic response by the external magnetic field. Theoretical study through the governing equation derived by Siliomis is carried out with numerical analysis by the Gauss Elimination Method. Using polar and magnetic effect parameters, theoretical equations and distributions for the velocity, apparent viscosity as the magnetic response are shown. Especially, in the region of strong magnetic field the specific property is appeared by finding a critical magnetic effect parameter for a polar effect parameter.

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The Vibration Characteristic of Large Main Steam Pipelines in Power Plant (발전소의 대형 주증기배관의 진동 특성)

  • Kim, Yeon-Whan;Lee, Hyun
    • Journal of KSNVE
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    • 제6권6호
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    • pp.709-715
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    • 1996
  • In recent years, the piping vibration in many Power Plants is being increased by the aged generating facilities due to a long time use. Generally, the pressure fluctuations associated with the flow-induced excitations in this case are broadband in nature. Mainly, the dominant sources of vibration are a vortex-shedding, plane waves and boundary layer turbulence. The peak level of the spectrum is proportional to the dynamic head. A severe disturbance in pipeline results in the generation of intense broadband internal sound waves which can propagate through the piping system. The characteristic frequencies of operating loads of 20%, 57%, 70%, 100% are 4 - 6 Hz and coincide with the results from impact hammering test and FEM analysis. We chose the wire energy absorbing rope restraint as a vibration reduction method after reviewing the various conditions such as site, installing space and economic cost etc. After installation, the vibration level was reduced about 54% in velocity.

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Simulation of free falling rigid body into water by a stabilized incompressible SPH method

  • Aly, Abdelraheem M.;Asai, Mitsuteru;Sonoda, Yoshimi
    • Ocean Systems Engineering
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    • 제1권3호
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    • pp.207-222
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    • 2011
  • A stabilized incompressible smoothed particles hydrodynamics (ISPH) method is utilized to simulate free falling rigid body into water domain. Both of rigid body and fluid domain are modeled by SPH formulation. The proposed source term in the pressure Poisson equation contains two terms; divergence of velocity and density invariance. The density invariance term is multiplied by a relaxed parameter for stabilization. In addition, large eddy simulation with Smagorinsky model has been introduced to include the eddy viscosity effect. The improved method is applied to simulate both of free falling vessels with different materials and water entry-exit of horizontal circular cylinder. The applicability and efficiency of improved method is tested by the comparisons with reference experimental results.

Design of a PIV objective maximizing the image signal-to-noise ratio

  • Chetelat Olivier;Kim Kyung Chun
    • 한국가시화정보학회:학술대회논문집
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    • 한국가시화정보학회 2001년도 Proceedings of 2001 Korea-Japan Joint Seminar on Particle Image Velocimetry
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    • pp.123-137
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    • 2001
  • PIV (particle image velocimetry) systems use a camera to take snapshots of particles carried by a fluid at some precise instants. Signal processing methods are then used to compute the flow velocity field. In this paper, the design of the camera objective (optics) is addressed. The optimization is done in order to maximize the signal-to-noise ratio of in-focus particles. Four different kinds of noise are considered: photon shot noise, thermal and read noise, background glow shot noise, and noise made by the other particles. A semi-empirical model for the lens aberrations of a two-doublet objective is first addressed, since further, it is shown that lens aberrations (low f-value $f_{\#}$) should be used instead of the Fraunhofer diffraction (high f-value) for the fitting of the particle image size with the pixel size. Other important conclusions of the paper include the expression of optimum values for the magnification M, for the exposure period $\tau$ and for the pixel size $\xi$.

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A Numerical Study of Smoke Movement by Fire In Atrium Space (화재 발생시 연기 거동에 대한 수치해석적 연구 - 아트리움 공간을 중심으로 -)

  • 노재성;유홍선;정연태
    • Journal of the Korean Society of Safety
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    • 제13권1호
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    • pp.70-76
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    • 1998
  • The smoke filling process for the atrium space containing a fire source is simulated using two types of deterministic fire models : Zone model and Field model. The zone model used is the CFAST(version 1.6) model developed at the Building and Fire Research Laboratories, NIST in the USA. The field model is a self-developed fire field model based on Computational Fluid Dynamics(CFD) theories. This article is focused on finding out the smoke movement and temperature distribution in atrium space which is cubic in shape. A computational procedure for predicting velocity and temperature distribution in fire-induced flow is based on the solution, in finite volume method and non-staggered grid system, of 3-dimensional equations for the conservation of mass, momentum, energy, species and so forth. The fire model i. e. Zone model and Field model predicted similar results for the clear height and the smoke layer temperature.

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