• 제목/요약/키워드: horizontal particle velocity

검색결과 85건 처리시간 0.023초

Quantitative observation of co-current stratified two-phase flow in a horizontal rectangular channel

  • Lee, Seungtae;Euh, Dong-Jin;Kim, Seok;Song, Chul-Hwa
    • Nuclear Engineering and Technology
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    • 제47권3호
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    • pp.267-283
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    • 2015
  • The main objective of this study is to investigate experimentally the two-phase flow characteristics in terms of the direct contact condensation of a steam-water stratified flow in a horizontal rectangular channel. Experiments were performed for both air-water and steam-water flows with a cocurrent flow configuration. This work presents the local temperature and velocity distributions in a water layer as well as the interfacial characteristics of both condensing and noncondensing fluid flows. The gas superficial velocity varied from 1.2 m/s to 2.0 m/s for air and from 1.2 m/s to 2.8 m/s for steam under a fixed inlet water superficial velocity of 0.025 m/s. Some advanced measurement methods have been applied to measure the local characteristics of the water layer thickness, temperature, and velocity fields in a horizontal stratified flow. The instantaneous velocity and temperature fields inside the water layer were measured using laser-induced fluorescence and particle image velocimetry, respectively. In addition, the water layer thickness was measured through an ultrasonic method.

열영동력이 수평 웨이퍼상의 입자침착에 미치는 영향 (Thermophoretic Effect on Particle Deposition Toward a Horizontal Wafer)

  • 배귀남;박승오;이춘식
    • 대한기계학회논문집
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    • 제18권1호
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    • pp.175-183
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    • 1994
  • To investigate thermophoretic effect on particle deposition, average deposition velocity toward a horizontal wafer surface in vertical airflow is measured keeping the wafer surface temperature different from the surrounding air temperature. In the present measurement, the temperature difference is maintained in the range from -10 to $4^{\circ}$ C Polystyrene latex (PSL) spheres of diameter between 0.3 and 0.8 .mu.m are used for the experiment. The number of particles deposited on a wafer surface is estimated from the measurements using a wafer surface scanner (PMS SAS-3600). Experimental data are compared with prediction model results.

정전효과가 있는 가열 수평웨이퍼로의 입자침착에 관한 해석 (Analysis on particle deposition onto a heated, horizontal free-standing wafer with electrostatic effect)

  • 유경훈;오명도;명현국
    • 대한기계학회논문집B
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    • 제21권10호
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    • pp.1284-1293
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    • 1997
  • The electrostatic effect on particle deposition onto a heated, Horizontal free-standing wafer surface was investigated numerically. The deposition mechanisms considered were convection, Brownian and turbulent diffusion, sedimentation, thermophoresis and electrostatic force. The electric charge on particle needed to calculate the electrostatic migration velocity induced by the local electric field was assumed to be the Boltzmann equilibrium charge. The electrostatic forces acted upon the particle included the Coulombic, image, dielectrophoretic and dipole-dipole forces based on the assumption that the particle and wafer surface are conducting. The electric potential distribution needed to calculate the local electric field around the wafer was calculated from the Laplace equation. The averaged and local deposition velocities were obtained for a temperature difference of 0-10 K and an applied voltage of 0-1000 v.The numerical results were then compared with those of the present suggested approximate model and the available experimental data. The comparison showed relatively good agreement between them.

Wafer Surface Scanner를 이용한 반도체 웨이퍼상의 입자 침착속도의 측정 (Measurement of Particle Deposition Velocity toward a Horizontal Semiconductor Wafer Using a Wafer Surface Scanner)

  • 배귀남;박승오;이춘식;명현국;신흥태
    • 설비공학논문집
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    • 제5권2호
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    • pp.130-140
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    • 1993
  • Average particle deposition velocity toward a horizontal semiconductor wafer in vertical airflow is measured by a wafer surface scanner(PMS SAS-3600). Use of wafer surface scanner requires very short exposure time normally ranging from 10 to 30 minutes, and hence makes repetition of experiment much easier. Polystyrene latex (PSL) spheres of diameter between 0.2 and $1.0{\mu}m$ are used. The present range of particle sizes is very important in controlling particle deposition on a wafer surface in industrial applications. For the present experiment, convection, diffusion, and sedimentation comprise important agents for deposition mechanisms. To investigate confidence interval of experimental data, mean and standard deviation of average deposition velocities are obtained from more than ten data set for each PSL sphere size. It is found that the distribution of mean of average deposition velocities from the measurement agrees well with the predictions of Liu and Ahn(1987) and Emi et al.(1989).

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진공 환경에서 가열되는 반도체 웨이퍼로의 입자 침착에 관한 수치해석적 연구 (A Numerical Study on Particle Deposition onto a Heated Semiconductor Wafer in Vacuum Environment)

  • 박수빈;유경훈;이건형
    • 한국입자에어로졸학회지
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    • 제14권2호
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    • pp.41-47
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    • 2018
  • Numerical analysis was conducted to characterize particle deposition onto a heated horizontal semiconductor wafer in vacuum environment. In order to calculate the properties of gas surrounding the wafer, the gas was assumed to obey the ideal gas law. Particle transport mechanisms considered in the present study were convection, Brownian diffusion, gravitational settling and thermophoresis. Averaged particle deposition velocities on the upper surface of the wafer were calculated with respect to particle size, based on the numerical results from the particle concentration equation in the Eulerian frame of reference. The deposition velocities were obtained for system pressures of 1000 Pa~1 atm, wafer heating of 0~5 K and particle sizes of $2{\sim}10^4nm$. The present numerical results showed good agreement with the available experimental ones.

고체입자가 부상된 자유 횡분류 유동에 대한 전산모사 연구 (I) -2상 분류궤적과 운동량 전달기구- (Numerical Simulation Study on Gas-Particle Two-Phase Jets in a Crossflow (I) -Two-Phase Jet Trajectory and Momentum Transfer Mechanism-)

  • 한기수;정명균
    • 대한기계학회논문집
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    • 제15권1호
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    • pp.252-261
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    • 1991
  • 본 연구에서는 2상 횡분류의 평균 유동특성을 비교적 정확히 예측할 수 있는 방법을 제시하는데 있다. 이를 위하여 2상 기체 분류속에 유입되는 자유흐름의 질량 유입을 Keffer와 Baines의 유입함수를 이용하기로 하며, 입자와 기체분류사이의 궤적 이탈을 고려하기로 한다. 이런 모델을 이용하여 2상 횡분류의 분출초기의 입자와 기 체분류의 속도비(particle to gas velocity ratio at the jet exit)가 유동에 미치는 영향을 알아보고자 한다.

웨이퍼 표면상의 입자침착에 관한 수치 시뮬레이션 (Numerical Simulation of Particle Deposition on a Wafer Surface)

  • 명현국;박은성
    • 대한기계학회논문집
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    • 제17권9호
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    • pp.2315-2328
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    • 1993
  • The turbulence effect of particle deposition on a horizontal free-standing wafer in a vertical flow has been studied numerically by using the low-Reynolds-number k-.epsilon. turbulence model. For both the upper and lower surfaces of the wafer, predictions are made of the averaged particle deposition velocity and its radial distribution. Thus, it is now possible to obtain local information about the particle deposition on a free-standing wafer. The present result indicates that the particle deposition velocity on the lower surface of wafer is comparable to that on the upper one in the diffusion controlled deposition region in which the particle sizes are smaller than $0.1{\mu}m$. And it is found in this region that, compared to the laminar flow case, the averaged deposition velocity under the turbulent flow is about two times higher, and also that the local deposition velocity at the center of wafer is high equivalent to that the wafer edge.

진공환경에서 수평 웨이퍼 표면으로의 입자침착 해석 (Analysis on Particle Deposition onto a Horizontal Semiconductor Wafer at Vacuum Environment)

  • 유경훈
    • 대한기계학회논문집B
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    • 제26권12호
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    • pp.1715-1721
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    • 2002
  • Numerical analysis was conducted to characterize the gas flow field and particle deposition on a horizontal freestanding semiconductor wafer under the laminar flow field at vacuum environment. In order to calculate the properties of gas, the gas was assumed to obey the ideal gas law. The particle transport mechanisms considered were convection, Brownian diffusion and gravitational settling. The averaged particle deposition velocities and their radial distributions fnr the upper surface of the wafer were calculated from the particle concentration equation in an Eulerian frame of reference for system pressures of 1 mbar~1 atm and particle sizes of 2nm~10$^4$ nm(10 ${\mu}{\textrm}{m}$). It was observed that as the system pressure decreases, the boundary layer of gas flow becomes thicker and the deposition velocities are increased over the whole range of particle size. One thing to be noted here is that the deposition velocities are increased in the diffusion dominant particle size range with decreasing system pressure, whereas the thickness of the boundary layer is larger. This contradiction is attributed to the increase of particle mechanical mobility and the consequent increase of Brownian diffusion with decreasing the system pressure. The present numerical results showed good agreement with the results of the approximate model and the available experimental data.

A Study on Velocity Profiles between Two Baffles in a Horizontal Circular Tube

  • Chang, Tae-Hyun;Lee, Chang-Hoan
    • Journal of Advanced Marine Engineering and Technology
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    • 제39권2호
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    • pp.136-142
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    • 2015
  • The shell and tube heat exchanger is an essential part of a power plant for recovering transfer heat between the feed water of a boiler and the wasted heat. The baffles are also an important element inside the heat exchanger. Internal materials influence the flow pattern in the bed. The influence of baffles in the velocity profiles was observed using a three-dimensional PIV (Particle Image Velocimetry) around baffles in a horizontal circular tube. The velocity of the particles was measured before the baffle and between them in the test tube. Results show that the velocity vectors near the front baffle flow along the vertical wall, and then concentrate on the upper opening of the front baffle. The velocity profiles circulate in the front and rear baffle. These profiles are related to the Reynolds number (Re) or the flow intensity. Velocity profiles at lower Re number showed complicated mixing to obtain the velocities and concentrate on the lower opening of the rear baffle as front wall. Numerical simulations were performed to investigate the effects of the baffle and obtain the velocity profiles between the two baffles. In this study, a commercial CFD package, Fluent 6.3.21 with the turbulent flow modeling, k-${\epsilon}$ are adopted. The path line and local axial velocities are calculated between two baffles using this program.

가열되는 회전원판으로의 입자 침착 해석 (Analysis on Particle Deposition on a Heated Rotating Disk)

  • 유경훈
    • 대한기계학회논문집B
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    • 제26권2호
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    • pp.245-252
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    • 2002
  • Numerical analysis was conducted to characterize particle deposition on a horizontal rotating disk with thermophorectic effect under laminar flow field. The particle transport mechanisms considered were convection, Brownian diffusion, gravitational settling and thermophoresis. The averaged particle deposition velocities and their radial distributions for the upper surface of the disk were calculated from the particle concentration equation in a Eulerian frame of reference for rotating speeds of 0∼1000rpm and temperature differences of 0∼5K. It was observed from the numerical results that the rotation effect of disk increased the averaged deposition velocities, and enhanced the uniformity of local deposition velocities on the upper surface compared with those of the disk at rest. It was also shown that the heating of the disk with ΔT=5K decreased deposition velocity over a fairly broad range of particle sizes. Finally, an approximate deposition velocity model for the rotating disk was suggested. The comparison of the present numerical results with the results of the approximate model and the available experimental results showed relatively good agreement between them.