• 제목/요약/키워드: Vacuum exhaust

검색결과 96건 처리시간 0.024초

진공용 공기베어링 배기시스템의 최적설계 (Optimal Design of an Exhaust System of a Vacuum-Compatible Air Bearing)

  • 김경호;박천홍;이후상;김승우
    • 한국정밀공학회지
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    • 제24권6호
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    • pp.86-95
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    • 2007
  • This paper presents the optimal design of an exhaust system of a vacuum-compatible air bearing using a genetic algorithm. To use the air bearings in vacuum conditions, the differential exhaust method is adopted to minimize the air leakage, which prevents air from leaking into a vacuum chamber by recovering air through several successive seal stages in advance. Therefore, the design of the differential exhaust system is very important because several design parameters such as the number of seals, diameter and length of an exhaust tube, pumping speed and ultimate pressure of a vacuum pump, seal length and gap(bearing clearance) influence on the air leakage, that is, chamber's degree of vacuum. In this paper, we used a genetic algorithm to optimize the design parameters of the exhaust system of a vacuum-compatible air bearing under the several constraint conditions. The results indicate that chamber's degree of vacuum after optimization improved dramatically compared to the initial design, and that the distribution of the spatial design parameters, such as exhaust tube diameter and seal length, was well achieved, and that technical limit of the pumping speed was well determined.

진공용 공기베어링의 성능해석 (Performance Analysis of a Vacuum-Compatible Air Bearing)

  • 김경호;박천홍;이후상;김승우
    • 한국정밀공학회지
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    • 제23권10호
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    • pp.103-112
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    • 2006
  • This paper describes a theoretical analysis and experimental verification on the performances of a vacuum-compatible air bearing, which is designed with a cascaded exhaust scheme to minimize the air leakage in a vacuum environment. The design of the vacuum-compatible air bearing equipped with the differential exhaust system requires great care because several design parameters, such as the number of exhaust stages, diameter of exhaust tube, pumping speed of a vacuum pump, and bearing clearance greatly influence the air leakage and thus degree of vacuum. In this study, a performance analysis method was proposed to estimate the performances of the air bearing, such as load capacity, stiffness, and air leakage. Results indicate that the load capacity and stiffness of the air bearing was improved as its boundary pressure, which was determined by the $1^{st}$ exhaust method, was lowered, and the dominant factors on the chamber's degree of vacuum were the number of exhaust stages, exhaust tube diameter and bearing clearance. A vacuum chamber and air bearing stage using porous pad were fabricated to verify the theoretical analysis. The results demonstrate that chamber pressure up to an order of $10^{-3}$ Pa was achieved with the air bearing stage operating inside the chamber, and this analysis method was valid by comparing predicted values with experimental data, for the mass flow rates from the porous pad, and pressures at each exhaust port and chamber, respectively.

진공 배기 및 초음파 접합 복합기 진동자 냉각에 관한 연구 (A Study on Cooling of Piezoelectric Element of Multifunction Equipment for Vacuum Exhaust and Ultrasonic Joining)

  • 박상준;이영림
    • 한국산학기술학회논문지
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    • 제13권4호
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    • pp.1511-1517
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    • 2012
  • 진공유리 배기공정을 위해 진공챔버나 진공튜브를 이용하는데 챔버 혹은 튜브 내부 전체를 진공으로 만들기 위한 시간과 경비가 과도하게 요구된다. 이러한 문제점을 해결하기 위해 상압에서 진공배기 및 초음파 접합이 동시에 가능한 복합기를 개발하고자 하였는데, 이 경우 진동자인 피에조 온도가 과도하게 상승하여 복합기의 냉각을 최적화할 필요성이 대두되었다. 따라서, 본 연구에서는 수치해석 및 실험을 통해 자연대류 및 강제대류 냉각방식의 효과를 규명하였고 이를 통해 진공 배기 및 초음파 접합 복합기의 냉각 성능을 최적화하였다.

Exhaust Manifold 용 오스테나이트계 스테인리스 강의 고온 변형특성 (HIGH TEMPERATURE DEFORMATION BEHAVIOR OF AUSTENITIC STAINLESS STEELS FOR EXHAUST MANIFOLD)

  • 이규동;하태권;정효태
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 추계학술대회 논문집
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    • pp.314-317
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    • 2007
  • Domestic automobile industries have been focusing their effort on development of exhaust manifolds using high temperature stainless steel. Exhaust manifolds fabricated with stainless steels can be categorized into tubular and cast ones. The former is usually manufactured by forming and welding process and the latter by vacuum casting process. In the present study, high temperature mechanical properties of 5 austenitic stainless steels, one was sand cast and the others vacuum cast, were investigated by performing a series of high temperature tensile tests and high temperature low cycle fatigue tests.

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선박용 소각로 이젝터의 배출온도 변화에 따른 유동과 배기특성 (The Stream and Exhaust Gas Characteristics for Variation of Exhaust Gas Temperature of Marine Incinerator Ejector)

  • 김태한
    • 한국해양공학회지
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    • 제14권2호
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    • pp.60-64
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    • 2000
  • An experimental study was performed to investigate the optimal ejector and operating condition of vessel incinerator. Exhaust gas temperature and secondary air which makes vacuum pressure at ejector throat regions were considered as an important factor. According to the measurement of pressure temperature and nitrogen oxides between non combustion and combustion we found the stream and exhaust gas characteristics of incinerator. This results can give us the exhaust gas temperature control system air pollutant reduction method and the optimum ejector design.

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반도체공정 고진공시스템 진공특성에 대한 배기도관 컨덕턴스 영향 전산모사 (Simulation of Conductance Effects on Vacuum Characteristics of High Vacuum System for Semiconductor Processing)

  • 김형택;서만재
    • 한국전기전자재료학회논문지
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    • 제23권4호
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    • pp.287-292
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    • 2010
  • Effect of conductance factors on performance of vacuum system was simulated for optimum design of vacuum system. In this investigation, the feasibility of modeling mechanism for VacSim$^{Multi}$ simulator was proposed. Application specific design of vacuum system is required to meet the particular process conditions for various industrial implementations of vacuum equipments. Geometry and length, diameter of exhaust pipeline were modeled as simulation modeling variables for conductance effects. Series vacuum system was modeled and simulated with varied dimensions and structures of exhaust pipeline. Variation of pipeline diameter showed the more significant effects on vacuum characteristics than that of pipeline length variations. It was also observed that the aperture structure of pipeline had the superior vacuum characteristics among the modeled systems.

액체로켓엔진 고고도 모사용 2차목 초음속 디퓨져 설계변수에 따른 특성 고찰 (Investigation of Characteristics of Second Throat Exhaust Diffuser for Simulating High-Altitude of Liquid Rocket Engine According to Design Parameter)

  • 문윤완;이은석
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2011년도 제37회 추계학술대회논문집
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    • pp.970-972
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    • 2011
  • 2차목 초음속 디퓨져 입구 직경에 따른 진공실 압력 변화를 고찰하였다. 디퓨져 입구는 세 종류로 변화시켰으며 각각의 경우에 대해 전산유체역학을 통해 계산을 수행하였다. 디퓨져 입구 크기에 따른 진공실의 압력 변화를 빠르게 상대비교하기 위해 비점성으로 가정한 Euler 방정식을 지배방정식으로 채택하였다. 결과로부터 디퓨져의 입구크기가 증가하면 진공실의 압력은 감소하는 것을 관찰할 수 있었다.

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배기다기관용 주강소재의 고온특성 평가 (Characterization of High Temperature Mechanical Properties of Cast Stainless Steels for Exhaust Manifold)

  • 이규동;하태권;정재영
    • 소성∙가공
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    • 제18권3호
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    • pp.217-222
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    • 2009
  • Automobile industries have been focusing their efforts on the development of exhaust manifolds using high temperature stainless steels. Exhaust manifolds fabricated with stainless steels can be categorized into tubular and cast ones. The former is usually manufactured by forming and welding process and the latter by vacuum casting process. In the present study, high temperature mechanical properties of 5 austenitic and 4 ferritic stainless steels were investigated by performing a series of high temperature tensile and low cycle fatigue tests. One of the austenitic stainless steels was vacuum cast and the others sand cast. Fatigue life of ferritic stainless steels was higher than that of austenitic ones.

고고도 모사용 초음속 디퓨져의 설계인자 및 작동인자에 대한 연구 (Study on Design- and Operating- Parameters of Supersonic Exhaust Diffusers Simulating high Altitude)

  • 윤상규;김진곤;성홍계;김용욱;오승협
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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    • pp.303-306
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    • 2007
  • 고고도 모사용 초음속 디퓨져의 설계 및 작동인자에 대한 영향을 파악하기 위하여 압축성 축대칭 Wavier-Stokes 방정식 기반의 two-layer k-$\varepsilon$ 난류 수치해석과 실험 결과를 비교 분석하였다. 디퓨져의 설계 및 작동인자인 노즐과 디퓨져의 면적비, 진공챔버의 크기, 제트의 공급압력에 대한 디퓨져내 유동 발달과 디퓨져 작동 특성을 살펴보았다.

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초음속 디퓨져 시동 과정에 관한 수치 모사; 초기 진공도에 따른 디퓨져 내부 충격파 구조의 발달 과정 (Numerical simulation on starting transients in supersonic exhaust diffuser; evolution of internal shock structures with different initial cell pressures)

  • 박병훈;임지환;윤응섭
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2005년도 제25회 추계학술대회논문집
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    • pp.46-55
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    • 2005
  • For the sea-level performance test of rocket motor designed to operate in the upper atmosphere, ejectors with no induced secondary flow are generally used, which serves dual purposes of evacuating the test cell and performing as a supersonic exhaust diffuser (SED). The main concern of this research is to simulate starting transients in order to visualize evolution of internal shock structures in SED with different initial cell (vacuum chamber) pressures. RANS code with low Reynolds $k-\varepsilon$ turbulence model was employed for these computations. Numerical results were compared with the pressure measurements previously performed [Proceedings of 2004 Annual Conference, KIMST], and showed good agreements with pressure-time history of measured data. In the case of low vacuum chamber pressure, abrupt impingement of the under-expanded supersonic jet from the nozzle onto the diffuser wall was observed, whereas initial impingement point was located downstream and moved slowly upstream in the case of non-vacuum chamber pressure. In spite of initially dissimilar evolution of shock structures, iso-mach contour revealed that the steady shock structures had little difference except the location of flow separation and normal shock.

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