• Title/Summary/Keyword: 유동 불균일

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Experimental investigation of impeller-volute interaction on a centrifugal turbomachinery (원심형 터보기계의 임펠러-볼류트 유동간섭에 관한 실험적 연구)

  • Lee, Kyung-Hoon;Joo, Won-Gu
    • 유체기계공업학회:학술대회논문집
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    • 2000.12a
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    • pp.219-225
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    • 2000
  • Primary function of a centrifugal compressor volute is to serve the flow from the impeller and diffuser to pipe system. But losses in volutes at off-design lead to poor stage efficiency and reduction of operating range. This is largely caused by the interaction between the impeller and volute flow fields. The magnitude of distortion is increased as the operating point is away from the design point and, as a result, the interaction between the impeller and volute is stronger. The objective of present study is to find the characteristics of tile flow in the diffuser and volute of the centrifugal compressor with rectangular cross-sectional volute. The measurements are carried out in two cases with the existence and nonexistence of the volute casing. The detailed pressure is presented by comparing the experimental results obtained at two cases with each others.

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Visualization of the Slurry Flow-Field during Chemical Mechanical Polishing by PIV (PIV를 이용한 Chemical Mechanical Polishing 공정 중의 연마용액 유동흐름 측정)

  • Shin Sanghee;Kim MunKi;Yoon Youngbin;Koh Young-Ho
    • 한국가시화정보학회:학술대회논문집
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    • 2004.11a
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    • pp.48-51
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    • 2004
  • Chemical Mechanical Polishing(CMP) is popularly used in production of semiconductor because of large area polishing ability probability of improvement for more integrated circuit. However, present CMP processing causes some non-uniformity errors which can be critical for highly integrated circuit. Previous studies predict that flow-field of slurry during CMP can create non-uniformity, but no quantitative measurement has conducted. In this study, using PIV, slurry velocity flow-field during CMP is measured by changing the ratio of RPM of pad and carrier with tuned PIV system adequate for small room in CMP machine and Cabot's non-groove pad Epad-A100. The result show that velocity of slurry is majorly determined by pad-rpm and the ratio of between carrier and pad rpm make some changes in streamlines.

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Manifold Diffuser of 2.5kW fuel cell design optimization (2.5kW급 연료전지 매니폴드 형상의 최적설계)

  • Lee, Chung-Eon;O, Seung-Hun;Gyeong, Seong-Hyeon;Kim, Jong-Eok
    • Proceeding of EDISON Challenge
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    • 2014.03a
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    • pp.625-630
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    • 2014
  • 연료전지의 성능을 결정짓는 가장 중요한 변수 중의 하나는 각 스택의 채널에 얼마나 균일하게 연료를 공급할 수 있느냐이다. 본 연구에서는 네 가지의 모델을 사용하여 연료전지 매니폴드 형상에 따른 최적 설계를 수행하였다. 위 네 가지 모델은 각기 다른 기하학적 형상을 가지며 Edison CFD를 이용하여 형상 내의 유동을 비교하였다. 초기 모델에서는, 입구부에서 매니폴드로 유입되는 유동의 확산이 잘 일어나지 않아 각 채널의 질량유량이 불균일한 분포를 보였으며 특히 속도가 빠른 중심 영역의 채널에 많은 연료가 유입되었다. 이를 위한 디퓨져 모델링이 제안되었으며 실속이 최소한도로 발생할 때 채널당 질량유량이 가장 균일하다고 가정하였다. 이를 위해 다양한 디퓨져 각을 가진 모델을 사용했고, 이론상으로 실속이 발생하지 않는 형상에서 가장 균일한 분포를 보임을 확인하였다.

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Development of Software for Electrochemical Plating Simulation Including Diffusion Layer Effects (확산층을 고려한 정밀 도금 Simulator 개발)

  • Seo, Seok;Lee, Ju-Dong;Gwon, Si-Hyeon;Ryu, Dong-Hwan
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2012.11a
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    • pp.76-77
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    • 2012
  • 전기 도금 시스템에서 전산모사 해석을 이용하여 도금층 두께를 정확히 예측하기 위해서 음극 표면의 확산층이 고려된 도금 Simulator를 개발하였다. 특정 형상의 경우 도금액 교반이 원활하지 않아 불균일한 도금이 이루어지는 경우가 있기 때문에 이를 예측하기 위해서는 교반 영향을 나타내는 확산층을 고려해야 한다. 유동해석을 통해 도금액 교반 조건 및 형상에 따른 음극 표면의 유속을 결정하고 유속별 도금액 DB를 구성하여 음극의 위치별 분극곡선을 차별화하여 유동 조건에 따른 확산층 변화를 고려하는 형태로 구현하였다. 유속별 도금액 DB는 실험 데이터 및 해석 데이터를 종합하여 구축하였다. 교반의 영향을 많이 받는 시스템을 대상으로 개발된 Simulator 결과의 타당성을 검증하였고 확산층 적용에 따른 도금 결과의 차이를 확인하였다.

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Studies on the Combustion Characteristics and NO Distribution in the Pulverized Coal Fired Boiler (대용량 미분탄 보일러의 연소특성 및 NO 분포 특성 연구)

  • Park, Ho-Young;Kim, Young-Joo
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.5
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    • pp.552-559
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    • 2008
  • Three dimensional numerical analysis were performed to investigate the combustion characteristics in a tangentially fired pulverized coal boiler. The predicted values at the outlet of economizer for the gas temperature, O$_2$, NO, CO were been compared with the measured data. By using the actual operating conditions of the power plant, the distribution of velocity, gas temperature, O$_2$, CO, CO$_2$ and NO as well as the particle tracking in the boiler were investigated. Throughout the present study, the non-uniform distribution of flue gas temperature in front of the final superheater might be resulted from the residual swirl flow in the upper furnace of the boiler. The present analysis on non-uniform distribution of the gas temperature could provide the useful information to prevent the frequent tube failure from happening in the final superheater of the tangentially coal-fired boiler.

Multiple-Silo Performance Assessment Model for the Wolsong LILW Disposal Facility in Korea - PHASE I: Model Development (월성 중저준위 처분시설 다중사일로 안정성 평가 모델 - 1단계: 모델개발)

  • Lim, Doo-Hyun;Kim, Jee-Yeon;Park, Joo-Wan
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.9 no.2
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    • pp.99-105
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    • 2011
  • An integrated model for groundwater flow and radionuclide transport analyses is being developed incorporating six underground silos, an excavated damaged zone (EDZ), and fractured host rock. The model considers each silo as an engineered barrier system (EBS) consisting of a waste zone comprising waste packages and disposal container, a buffer zone, and a concrete lining zone. The EDZ is the disturbed zone adjacent to silos and construction & operation tunnels. The heterogeneity of the fractured rock is represented by a heterogeneous flow field, evaluated from discrete fractures in the fractured host rock. Radionuclide migration through the EBS in silos and the fractured host rock is simulated on the established heterogeneous flow field. The current model enables the optimization of silo design and the quantification of the safety margin in terms of radionuclide release.

Investigation of Uniformity in Ceria based Oxide CMP (Ceria 입자 Oxide CMP에서의 연마 균일도 연구)

  • Lim, Jong-Heun;Lee, Jae-Dong;Hong, Chang-Ki;Cho, Han-Ku;Moon, Joo-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.11a
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    • pp.120-124
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    • 2004
  • 본 연구는 Diluted Ceria 입자를 사용한 $SiO_2$(Oxide) CMP 현상에 대한 내용이다. Ceria Slurry의 경우 Silica Slurry와 비교하였을 때 Oxide Wafer 표면과 축합 화학반응을 일으키며 Chemistry Dominant한 CMP Mechanism을 따르고, Wafer Center Removal Rate(RR) Fast 의 특성을 가진다. Ceria Slurry의 문제점인 연마 불균일도를 해결하기 위해 Tribological System을 이용하였다. CMP Tribology는 Pad-Slurry 유막-Wafer의 System을 가지며 윤활막에 작용하는 마찰계수(COF)가 주요 인자이다. Tribology에 적용되는 Stribeck Curve를 통해 Slurry 윤활막의 두께(h) 정도를 예상할 수 있으며, 이 윤활막의 두께를 조절함으로써 Uniformity 향상이 가능하다. 이 Ceria Slurry CMP의 연마 불균일도를 향상시킬 수 있는 방법으로 pH 조절 및 점도 증가가 있다. Ceria 입자 CMP는 분산액의 pH 변화에 강한 작용을 받게 되며 PH5 근방에서 최적화된 Uniformity가 가능하다. 점도를 증가시키는 경우 유막 h가 증가하게 되어 Ceria Slurry의 유동이 균일 분포 상태에 가까워지며 Wafer Uniformity 향상이 가능하다.

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The Effects of Groove Dimensions of Pad on CMP Characteristics (패드 그루브의 치수가 CMP 연마특성에 미치는 영향)

  • Park Ki-Hyun;Kim Hyoung-Jae;Choi Jae-young;Seo Heon-deok;Jeong Hae-do
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.3 s.234
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    • pp.432-438
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    • 2005
  • CMP characteristics such as material removal rate and edge effect were measured and investigated in accordance with pad grooving effect, groove width, depth and pitch. GSQ (Groove Stiffness Quotient) and GFQ (Groove Flow Quotient) were proposed to estimate pad grooving characteristics. GSQ is defined as groove depth(D) divided by pad thickness(T) and GFQ is defined as groove width(W) divided by groove pitch(P). As GFQ value increased, material removal rate increased some point but gradually saturated. It seems that material removal rate is not affected by each parameter respectively but by interaction of these parameters such as groove dimensions. In addition, an increase in GFQ and GSQ causes edge effect to be improved. Because, pad stiffness decreases as GSQ and GFQ increase. In conclusion, groove influences relative pad stiffness although original mechanical properties of pad are unchanged by grooving. Also, it affects the flow of slurry that has an effect on the lubrication regime and polishing results. The change of groove dimensions has influence on pad stiffness and slurry flow, so that polishing results such as removal rate and edge effect become changed.

Development of Simulation Program of Vehicle Thermal Managements System (차량용 열제어 관리 시스템의 성능 시뮬레이션 프로그램 개발)

  • Bae, Suk-Jung;Heo, Hyung-Seok;Kim, Hyung-Chul
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.345-348
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    • 2008
  • The computer-aided performance simulation can reduce periods for development of products and cut down on the cost comparing with former trial-and-error procedures. This study has developed a simulation program for a vehicle thermal management system integrating an engine cooling system and an air conditioning system considering interactions and arrangement of air side heat exchangers such as power steering oil cooler, air-cooled transmission oil cooler, condenser, and radiator. The program may be also used for the system performance analysis according to the configuration of the engine coolant side heat exchangers such as water-cooled transmission oil cooler, EGR cooler, and heater core. Experiments utilizing an environmental wind tunnel has been conducted to assess the performance of the system according to the arrangement of air side heat exchangers. Some modification of the coolant loop layout can enhance the heat core performance up to 7% according to the results of the simulations.

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An investigation of non-uniform metal flow during rectangular battery case using impact extrusion process (충격압출 공정을 이용한 직사각형 배터리 케이스 성형 시 불균일 금속 유동 발생 원인 고찰)

  • Lim, Jae-Hyuk;Kim, Yong-bae;Lee, Jong-sup
    • Design & Manufacturing
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    • v.10 no.2
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    • pp.24-28
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    • 2016
  • In this study, relevant to impact extrusion process of the rectangular batter case for electric vehicles, numerical and experimental analyses were conducted to reduce the earring defects induced in the unevenness of metal flow. Since the earring is caused by the non-uniform metal flow induced in the friction and aspect ratio in the bottom section. As a way to reduce the earring, variable land die concept was applied. In order to analyze numerically the complex metal flow by using commercial finite element package, DEFORM 3D, impact extrusion process was simplified in upsetting mode at bottom section and extrusion mode at land section. The impact extrusion experiments were conducted to verify the assessment of process parameter for impact extrusion. As results, variable land die which has longer longitudinal section makes reduce earring defects. In addition, it was confirmed that the effect that slug shape like dog-bone also can reduce the earring. This study is expected to be able to present the useful design guidelines for manufacturing the battery case.