• 제목/요약/키워드: Driving nozzle

검색결과 68건 처리시간 0.024초

The Starting Characteristics of the Steady Ejector-Diffuser System

  • Gopalapillai, Rajesh;Kim, Heuy-Dong;Matsuo, Shigeru;Setoguchi, Toshiaki
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2008년 영문 학술대회
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    • pp.680-685
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    • 2008
  • The ejector is a simple device which can transport a low-pressure secondary flow by using a high-pressure primary flow. In general, it consists of a primary driving nozzle, a mixing section, and a diffuser. The ejector system entrains the secondary flow through a shear action generated by the primary jet. Until now, a large number of researches have been made to design and evaluate the ejector systems, where it is assumed that the ejector system has an infinite secondary chamber which can supply mass infinitely. However, in almost all of the practical applications, the ejector system has a finite secondary chamber implying steady flow can be possible only after the flow inside ejector has reached an equilibrium state after the starting process. To the authors' best knowledge, there are no reports on the starting characteristics of the ejector systems and none of the works to date discloses the detailed flow process until the secondary chamber flow reaches an equilibrium state. The objective of the present study is to investigate the starting process of an ejector-diffuser system. The present study is also planned to identify the operating range of ejector-diffuser systems where the steady flow assumption can be applied without uncertainty. The results obtained show that the one and only condition in which an infinite mass entrainment is possible is the generation of a recirculation zone near the primary nozzle exit. The flow in the secondary chamber attains a state of dynamic equilibrium at this point.

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기체-액체 이젝터의 디퓨저 형상에 대한 연구 (STUDY ON THE PERFORMANCE OF THE SHAPE OF THE AIR-LIQUID EJECTOR DIFFUSER)

  • 장진우;신원협;박영철
    • 한국산학기술학회논문지
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    • 제15권11호
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    • pp.6412-6418
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    • 2014
  • 본 논문은 기체-액체 이젝터의 수치해석연구에 초점을 맞추고 있다. 이젝터는 구동유체가 노즐을 통해 고속으로 분출될 때, 구동노즐 출구 주변에 진공압이 형성되어 주변의 기체와 운동량 교환을 통하여 저압의 유체를 보다 높은 압력으로 압축하여 수송하는 장치이다. 기체-액체 이젝터는 상용 소프트웨어 ANSYS-CFX 14.0을 사용하여 다상의 CFD 분석을 통해 연구한다. 구동유체는 물을 사용하여 구동되며, 실제로는 공기가 아닌 오존을 사용하여 배출 된다. 기체-액체 이젝터의 디퓨저의 형상에 따라 성능 차이를 비교한다. 결과 기체-액체 이젝터의 성능에 미치는 다양한 요인을 제공 한다. 그리고 제안 된 수치 모델은 기체-액체 이젝터의의 최적 설계에 매우 도움이 될 것다.

과냉각수조에서 증기응축 특성에 관한 실험적 연구 (Experimental Study on Characteristics of Steam Condensation in a Sub-cooled Water Pool)

  • 김환열;조석;송철화;정문기;최상민
    • 에너지공학
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    • 제8권2호
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    • pp.298-308
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    • 1999
  • 과냉각수조로 분사되는 증기의 직접접촉 응축특성을 알아보기 위하여 다섯 개의 수평 노즐에 대해 증기 질량유량과 수조 온도를 여러 가지로 변화시키면서 실험적 연구를 수행하였다. 증기응축현상을 육안관찰과 고속 비디오 카메라를 사용한 방법으로 분석한 결과, 안정된 증기제트인 경우 증기 질량속과 수조온도가 변화함에 따라 타원형 및 원추형 증기제트 형상이 나타나는 것을 관찰하였다. 증기제트 팽창비, 증기제트 길이 및 응축연전달계수를 구하였고, 증기 질량속, 수조온도 및 노즐 내경이 미치는 영향을 분석하였다. 증기제트 길이와 응축열전달계수를 증기 질량속 및 응축추진 포텐셜의 함수로 나타낸 상관식을 구하였다. 증기제트 내부와 주위 수조온도 분포를 구했으며 증기 질량속, 수조온도 및 노즐 내경이 미치는 영향을 분석하였다. 처깅, 천이처깅, 응축진동, 안정응축, 방울응축진동 및 간헐진동응축 등 여섯 가지 영역으로 구분된 응축 영역도를 작성하였다. 그 외, 수조 벽면에서의 동압을 측정하였고, 증기 질량속과 수조온도에 따라 변화하는 증기 응축모드와 동압과는 밀접한 연관성이 있음을 확인하였다.

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직접구동 피에조 인젝터의 CRDi 단기통 디젤엔진 연소 특성 분석 (Analysis on Combustion Characteristics of CRDi Single-cylinder Diesel Engine with Direct Needle-driven Piezo Injector)

  • 정명철;성기수;김상명;이진욱
    • 한국자동차공학회논문집
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    • 제22권5호
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    • pp.108-115
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    • 2014
  • In this study, experimental approaching method was applied under and single-cylinder engine to research the performance of direct needle-driven piezo injector (DPI) for CR direct-injection. As key-point factor of this DPI that relies on direct-acting operating of injector needle, unlike conventional hydraulic-servo, its nozzle needle can be directly driven by piezo actuator. Thus, effect of direct-acting injection of DPI on diesel combustion and emission characteristics was investigated under common-rail single-cylinder direct-injection engine, equipped with three different driving mechanism, including indirect-acting solenoid, piezo and DPI system. As main results, it found that a direct-acting piezo injector has higher of IMEP. And it has higher heat release rate during premixed combustion and mixing controlled combustion phase due to its higher heat release, even though nitrogen oxide (NOx) formations were increased slightly.

Oil-Jet 윤활시 가스터어빈용 고속 Ball Bearing 윤활특성 (Lubrication Characteristics of High-Speed Ball Bearing with Oil-Jet Lubrication)

  • 김기태
    • Tribology and Lubricants
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    • 제12권4호
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    • pp.28-34
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    • 1996
  • The lubrication characteristics of high-speed ball bearings have been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flow rates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 2969 N axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

램제트 천이 시 점화 및 연소 특성 연구 (A Study on the Ignition and Combustion Characteristics During the Transition from the Rocket Booster to Ramjet Sustainer)

  • 윤재건;윤현걸;길현용
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2011년도 제37회 추계학술대회논문집
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    • pp.996-999
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    • 2011
  • 통합형 로켓 부스터 램제트(IRR) 엔진에서의 점화 및 램제트 단계에서의 유동 및 연소의 동적특성에 대한 연구를 수행하였다. 연구대상모델은 흡입구 전방 자유흐름 영역에서부터 노즐 출구까지 엔진 전체 유로가 포함되도록 하였으며, 로켓 부스터에 대한 연구를 통해 얻어진 유동장 계산 결과를 본 연구의 초기조건으로 사용함으로써 엔진의 작동 과정 전체에 대한 정보를 얻을 수 있도록 하였다. 본 연구에서는 점화과정에서 화염전파에 가장 영향을 미치는 요소와 유동의 진동을 유발하고 지속시키는 메커니즘에 대해 연구를 수행하였다.

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다른 구동방식을 갖는 고압 디젤 엔진용 인젝터의 Pilot 분무 특성 해석 (Analysis of Pilot Spray Characteristics of Different Driven Injectors for High Pressure Diesel Engine)

  • 배장웅;김하늘;이진욱;강건용;류정인
    • 한국연소학회:학술대회논문집
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    • 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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    • pp.251-256
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    • 2003
  • The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors, solenoid-driven and piezo-driven type, with different electric driving characteristics So, three common-rail injectors with different electric current wave were used in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. Also the CFD analysis was carried out for fuel behavior under high pressure in between needle and nozzle of solenoid-driven injector to know the condition of initial injection at experiment test. It was found that pilot injection of common-rail system was effected by rate of injection and temperature of injected fuel and electrical characteristic of the driven injector.

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궤도천이 및 자세제어 시스템의 연구개발 동향과 전망 (Recent Progress in R&D and Prospect of Divert and Attitude Control System(DACS))

  • 김성수;허환일
    • 한국추진공학회지
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    • 제16권6호
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    • pp.62-72
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    • 2012
  • 우주 비행체와 유도 미사일에 적용되는 궤도천이 및 자세제어 시스템(이하 DACS)은 비행체의 궤도를 천이시키거나 미세한 자세 제어를 수행하게 된다. DACS를 개발하기 위해서는 추력변화 최대화를 위한 핀틀/노즐의 형상 조합, 핀틀 구동력 최소화를 위한 공력하중 저감, 다축 제어 알고리즘에 대한 연구가 중요하다. 본 논문에서는 이러한 DACS 시스템에 대한 소개와 분류, 국내외 연구 개발 동향에 대해 살펴보고 향후 연구 개발 전망을 제시하였다.

메탈 인쇄용 압전 헤드 제작 프로세스 연구 (Studies of Printing Head Fabrication Process For Mano Metal Printing System)

  • 유영석;김영재;심원철;박창성;정재우;오용수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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    • pp.1623-1624
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    • 2006
  • It is a paper for design, manufacture and estimation of industry inkjet head. Simulations for Actuator, Ink flow and Ejection are executed for securing design ability. Relations between droplet and properties of ink are explained closely through simulation for nozzle. Actually, two silicon plates are made by dry and wet etching and directly bonded. PZT materials is attached on the bended ink flow part and cut to $540{\mu}m$ interval by dicing saw. Actuator was seen variation within 10% between simulation and actual head. Through the ejection estimation, it is shown that stabilized driving voltages change according to viscosity and surface tension of metal ink. Using the metal ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject the stable droplets with 5m/s, 20 pl, 5 kHz.

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Oil-Jet Ball 윤활시 가스터빈용 고속 Ball Bearing 윤활특성

  • 김기태;권우성
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1996년도 제24회 춘계학술대회
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    • pp.86-93
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    • 1996
  • The lubrication characteristics of high-speed ball bearings has been investigated empirically using 45mm bore split inner ring ball bearings employed in small industrial gas turbine engines with oil-jet lubrication method. For the close structural simulation, experiments carried out with bearing mounting supports of real engines, such as bearing housings and oil nozzle assemblies with squeeze film dampers. Thus the results of tests can be directly applied to the design and the development of gas turbine engines. Testing was done by varying operating speeds, axial load on bearings, and lubricant flowrates. During testing, the temperature of bearing at outer-ring face, the power consumption of the driving motor, and the rotating resistance of the bearing were measured. From this study, the representative factors for lubrication characteristics at high speed was found, and the most important one was not operating speed but axial load up to 1.95 million dmN speed and 303 kgf axial load. Furthermore, the detailed variation of the rotational resistance of the bearing could be visualized by measuring the change of the radial load under the bearing supports. The rotational resistance consists of the frictional resistance and the bearing-cavity oil resistance.

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