• Title, Summary, Keyword: 캐비티압력

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PIV Measurement on Collapse Behavior of Cavitation (캐비테이션 붕괴거동에 관한 PIV 유동계측)

  • Gim, Ok-Sok;Han, Min-Su;Kim, Seong-Jong;Lee, Gyoung-Woo
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • pp.130-131
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    • 2013
  • 캐비테이션 현상은 고 유속 환경에서 발생(inception), 성장(growth), 붕괴(collapse) 및 소멸(disappearance) 과정이 반복적으로 일어나며 그 과정에서 기포붕괴에 따른 큰 충격압력을 방지하려는 분야와 이를 능동적으로 산업분야에 적용하려는 분야로 크게 대별된다. 본 연구에서는 캐비테이션의 붕괴거동을 수중 초음파 진동자에서 미세기포를 발생시켜 PIV기법을 이용하여 유동장을 계측하였다. 초음파 진동자는 직경 16 mm이며, 진동주파수는 20 kHz, 진폭은 $5{\mu}m$, $10{\mu}m$, $30{\mu}m$$50{\mu}m$를 각각 적용하였다. 유동구조, 난류강도, 레이놀즈 응력에 대한 통계적 유동정보를 계측한 결과 충격압력의 원인으로 알려진 캐비티 붕괴로 인해 유동특성을 확인하였다.

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Forming Characteristics with Cavity Pressure and Temperature Signal Inside Mold in High-Pressure Resin Transfer Molding Process of Carbon Fiber Reinforced Composite Material (탄소섬유강화복합소재의 고압수지이송성형공정에서 금형 내 캐비티의 압력 및 온도신호에 따른 성형특성)

  • Han, Beom-Jeong;Jeong, Yong-Chai;Kim, Sung-Ryul;Kim, Ro-Won;Kang, Myung Chang
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.6
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    • pp.81-86
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    • 2017
  • The high-pressure resin transfer molding (HP-RTM) process has a very effective for the mass production of carbon fiber reinforced plastic (CFRP) for light weight in the automotive industry. In developing robust equipment, new process and fast cure matrix systems reduces significantly the cycle time less than 5 minutes in recent years. This paper describes the cavity pressure, temperature and molding characteristics of the HP-RTM process. The HP-RTM mold was equipped with two cavity pressure sensors and three temperature sensors. The cavity pressure characteristics of the HP-RTM injection, pressurization, and curing processes were studied. This experiment was conducted with selected process parameters such as mold cap size, maximum press force, and injection volume. Consequently, this monitoring method provides correlations between the selected process parameters and final forming characteristics in this work.

An Experimental Study of Direct Containment Heating Phenomena (격납용기 직접가열 현상에 관한 실험적 연구)

  • Chanyoung Chung;Gyoodong Jeun;Bang, Kwang-Hyun;Kim, Moohwan
    • Nuclear Engineering and Technology
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    • v.25 no.3
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    • pp.413-423
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    • 1993
  • This paper reports an experimental study of direct containment heating (DCH) which would occur if the primary system pressure is still high at the time of vessel breach during a light water reactor core melt accident. The experiments were conducted in 1/30-scale cavity models of Kori unit 1 and 2 and Young Kwang unit 3 and 4 nuclear power plants. One 1/20-scale model of the Kori plant was also used to investigate the scaling effect. The primary variables in the experiments were initial vessel pressure, vessel breach size and cavity geometry. It is observed that higher initial pressure and larger breach size enhance the melt dispersal fraction. Also, the cavity geometry appears to affect the dispersal rate greatly. A simple correlation of melt dispersal fraction is proposed in terms of nondimensional effective period. This correlation shows good agreement with the present experimental data, the KAIST data and the BNL data.

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Design of Injection Mold with Cavity Pressure/Temperature Sensors and Molding for Standard Tensile Test Specimen (내압력.온도센서를 갖는 표준 인장시편용 사출금형설계 및 성형)

  • Lee D.M.;Han B.K.;Lee O.S.;Lee Sung-Hee
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.1416-1419
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    • 2005
  • Design and manufacturing of plastic injection mold with cavity pressure/temperature sensors were performed in the present study for tensile test specimen. Standards of mold-base and tensile test specimen were used to design an injection molding system. Cavity pressure and temperature sensors were placed on the side of fixed platen of injection mold machine to prevent them from external impact damage. Injection molding experiments with variations of injection speed and melt temperature were performed and polycarbonate tensile specimens were prepared for the tensile test. It was shown that injection molding processing parameters can have effect on the mechanical properties of the plastic injection molded part.

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PIV Analysis of Cubic Channel Cavity Flow (입방형 채널 캐비티 유동의 PIV 해석)

  • 조대환;김진구;이영호
    • Journal of Advanced Marine Engineering and Technology
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    • v.21 no.5
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    • pp.557-563
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    • 1997
  • The unsteady flow in three-dimensional cubic cavity with narrow channel at upper region is investigated experimentally for three kinds of Reynolds number, 1*10/sup 4/, 3*10/sup 4/ and 5*10/sup 4/ based on the cavity width and cavity inlet mean flow velocity. Instant velocity vectors are obtained simultaneously at whole field by PIV(Particle Image Velocimetry). Wall pressure distributions are estimated using Poisson equation from the velocity data. Results of PIV reveal that severe unsteady flow fluctuation within the cavity are remarkable at all Reynolds numbers and sheared mixing layer phenomena are also found at the region where inlet driving flow is collided with the clock-wise rotating main primary vortex. Instant velocity profiles reveal that deformed forced vortex formation is observed throughout the entire region and spanwise kinetic energy migration is conspicuous.

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Injection Mold with Cavity Pressure/Temperature Sensors for Standard Tensile Test Specimen (내압력.온도센서를 갖는 표준 인장시편용 사출금형)

  • Lee, Do-Myoung;Han, Byoung-Kee;Lee, Sung-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.11
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    • pp.84-90
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    • 2007
  • In this study, design and manufacturing of plastic injection mold with cavity pressure/temperature sensors were performed fur tensile test specimen. International standard system for plastic tensile specimen was applied to design an injection molding system. Cavity pressure and temperature sensors were placed on the side of fixed platen of the injection mold to prevent them from external impact damage. Injection molding experiments with variations of injection speed and melt temperature were performed and then tensile test of the manufactured polycarbonate specimens was also performed. It was shown that injection molding processing parameters can have effect on the mechanical properties of the plastic injection molded part.

저온 용융 합금물을 이용한 울진 1,2호기 원전 캐비티에 대한 노심용융물 고압분출 실험 연구

  • 박래준;김상백;김희동;김찬수;이규정
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.783-788
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    • 1998
  • 국내 프랑스 가압경수형 원전인 울진 1,2호기 캐비티의 격납건물 직접가열에 대한 특성을 분석하기 위하여 노심용융물 고압분출 실험을 수행하였다. 본 연구에서는 환형통로 면적과 파손 직경에 따라 원자로용기 압력을 변화시키면서 용융물을 저온 용융 합금물인 Wood's Metal, 증기를 질소기체로 각각 모의하여 실험을 수행하였으며, 실험 결과는 물을 용융물 상사물로 사용한 전년 실험 결과(1)와 비교.분석하였다. 실험결과, 밀도가 물보다 큰 저온 용융 합금물을 사용한 경우는 물을 사용한 실험결과보다 밀도와 용융물의 벽면 고화고착 때문에 격납건물로 방출되는 용융물 양이 적게 나타났다. 물을 상사물로 사용한 경우와 같이 노심 용융물 고압분출에는 원자로 용기 파손직경이 많은 영향을 미치고 환형통로 면적은 큰 영향을 미치지 않는 것으로 나타났다. 노심용융물 고압분출 실험에 중요한 영향을 미치는 실험 상사물의 밀도와 용융물의 벽면 고화부착에 대해서는 종합적으로 분석하는 추가 연구가 필요하다.

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The Pressure and Degree of Filling Balance between Cavity to Cavity in Multi-Cavity Injection Mold (다수 캐비티 금형에서 캐비티 간의 압력과 균형충전도)

  • Noh, Byeong-Su;Park, Tae-Won;Jeong, Yeong-Deug
    • Journal of the Korea Society of Die & Mold Engineering
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    • v.2 no.6
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    • pp.33-37
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    • 2008
  • Almost all injection molds have multi-cavity, which are designed with geometrically balanced runner system in order to made filling balance between cavity to cavity during injection molding. However, filling imbalance has been existed in the geometrically balanced runner system. In this study, we made an experiment and investigated that are filling balanced according to material. Also, in case of filling imbalance was occurred, we conducted experiments in order to find out difference of cavity pressure with cavity pressure sensor. When filling imbalance was occurred between cavity to cavity, we investigated the filling imbalance and pressure differences by computer-aided engineering(CAE).

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Two-Dimensional Laminar Natural Convection Heat Transfer with Surface Radiation in a Cavity (캐비티내에서 표면복사를 고려한 2차원 층류 자연대류 열전달)

  • Park, H.Y.;Park, K.W.;Han, C.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.4 no.3
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    • pp.217-232
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    • 1992
  • A Numerical study on two-dimensional laminar natural convection with and without surface radiation in fully or partially open square cavity was performed. The cavity has one vertical heated wall facing a vertical opening and two horizontal insulated walls. The pressure boundary condition was applied to the opening instead of the velocity boundary condition. The results of this study showed that the increase of partition length decreased the convective and the radiative Nusselt numbers. It was also found that the increase of wall emissivity decreased the convective Nusselt numbers but increased the radiative Nusselt numbers.

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Design of Vent Relief Valve for Bi-level Pressure Setting of Oxidizer Tank (산화제 탱크 2단계 압력 설정을 위한 벤트/릴리프밸브 설계)

  • Koh, Hyeonseok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.1051-1053
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    • 2017
  • We have designed the vent relief valve to set bi-level safety pressure for oxidizer tank. The minimum cavity volume was calculated to reduce the pressure deviation, and the valve operation characteristics was analyzed by using modeling. We have a plan to manufacture the validation model based on the analysis results.

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