• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.485-490
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• 2000

This paper dipicts the computational results for the axisymmetric subsonic/sonic ejector systems with a second throat. The numerical simulations are based on a fully implicit finite volume scheme of the compressible Reynolds-Averaged Navier-Stokes equation in a domain that extends form the stagnation chamber to the ejector diffuser exit. In order to obtain practical design factors for subsonic/sonic ejector systems, the ejector throat area, the mixing section configuration, and the ejector throat length were changed in computations. For the subsonic/sonic ejector systems operating in the range of low operation pressure ratio, the effects of the design factors on the flow are discussed.

• 대한기계학회논문집B
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• 제25권2호
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• pp.269-276
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• 2001

This paper dipicts the computational results for the axisymmetric subsonic/sonic ejector systems with a second throat. The numerical simulations are based on a fully implicit finite volume scheme of the compressible Reynolds-Averaged Navier-Stokes equation in a domain that extends from the stagnation chamber to the ejector diffuser exit. In order to obtain practical design factors for subsonic/sonic ejector systems, the ejector throat area, the mixing section configuration, and the ejector throat length were changed in computations. For the subsonic/sonic ejector systems operating in the range of low operation pressure ratio, the effects of the design factors on the flow are discussed.

• 한국추진공학회지
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• 제4권3호
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• pp.1-10
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• 2000

본 연구에서는 아음속/음속 이젝터의 성능을 평가하고, 공학적 설계를 위한 기초적 연구의 일환으로 일차원 기체역학 이론을 이용하여 이론해석을 수행하였다. 이론해석에서는 1차노즐의 유량계수, 디퓨저의 손실계수를 도입하여, 아음속/음속 이젝터의 목면적비, 유량비, 2차정체실의 압력 등을 이젝터 압축비의 함수로 도출하였다 본 연구에서 제시된 이론해석법은 아음속/음속 이젝터의 성능을 평가하는데 유용할 뿐만 아니라 이젝터 설계를 위한 자료로 활용될 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.479-484
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• 2000

For the purpose of a cost effective design of practical subsonic/supersonic ejector systems, an experiment was carried out using a superheated steam as a primary driving flow. The superheated steam jet was produced by several different kinds of subsonic and supersonic nozzles. The secondary flow of atmospheric air inside a plenum chamber was drawn into the primary steam jet. The vacuum performance of the plenum chamber was investigated for a wide range of the ejector operation pressure ratio. The result showed that the static pressure of the mixed flow at the ejector throat is only a function of the ejector operation pressure ratio, regardless of the primary nezzle type employed.

• 한국추진공학회지
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• 제4권4호
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• pp.26-35
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• 2000

본 연구에서는 어떤 2차목을 가지는 축대칭 아음속/음속 이젝터 유동을 조사하기 위하여, 수치해석법을 이용하였다. 수치계산은 2차 정체실에서 이젝터 디퓨저 출구까지의 넓은 계산영역에 대하여, 압축성 Reynolds-Averaged Navier-Stokes방정식에 완전 음적 유한 체적법을 적용하였다. 축대칭 아음속/음속 이젝터 시스템에 대한 실용적 설계 인자를 얻기 위해서, 이젝터 목면적, 혼합부의 형상, 그리고 이젝터 목 길이를 변화시켜, 비교적 낮은 작동압력비로 운전되는 이젝터 유동특성의 변화를 조사하였다 계산 결과들은 2차 정체실의 진공성능에 미치는 작동압력비와 아젝터 형상의 영향을 조사하는데 활용되었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.156-160
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• 2007

Ejector system is a device to transport a low-pressure secondary flow by using a high-pressure primary flow. Ejector system is, in general, composed of a primary nozzle, a mixing section, a casing part for suction of secondary flow and a diffuser. It can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejector system is simple in construction and has no moving parts, so it can not only compress and transport a massive capacity of fluid without trouble, but also has little need for maintenance. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an applicable model and operating conditions for an ejector in the condition of sonic and subsonic, which can be extended to the hydrogen fuel cell vehicle. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Optimization technique and numerical simulation was adopted for an optimal geometry design and satisfying the required performance at design point of ejector for hydrogen recirculation. Also, some sonic and subsonic ejectors with the function of changing nozzle position were manufactured precisely and tested for the comparison with the calculation results.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.256-259
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• 2008

Ejector system is a device to transport a low-pressure secondary flow by using a high-pressure primary flow. Ejector system is, in general, composed of a primary nozzle, a mixing section, a casing part for suction of secondary flow and a diffuser. It can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejector system is simple in construction and has no moving parts, so it can not only compress and transport a massive capacity of fluid without trouble, but also has little need for maintenance. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an applicable model and operating conditions for an ejector in the condition of sonic and subsonic, which can be extended to the hydrogen fuel cell vehicle. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Optimization technique and numerical simulation was adopted for an optimal geometry design and satisfying the required performance at design point of ejector for hydrogen recirculation. Also, some ejectors with a various of nozzle throat and mixing chamber diameter were manufactured precisely and tested for the comparison with the calculation results.

• 대한기계학회논문집B
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• 제29권5호
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• pp.554-560
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• 2005

A new method to improve the efficiency of a hydrogen fuel cell system was introduced by using variable sonic/supersonic ejectors. To obtain the variable area ratio of the nozzle throat to ejector throat which controls the mass flow rate of the suction flow, the ejectors used a movable cylinder inserted into a conventional ejector-diffuser system. Experiments were carried out to understand the flow characteristics inside the variable ejector system. The secondary mass flow rates of subsonic and supersonic ejectors were examined by varying the operating pressure ratio and area ratio. The results showed that the variable sonic/supersonic ejectors could control the recirculation ratio by changing the throat area ratio, and also showed that the recirculation ratio increased fur the variable sonic ejector and decreased for the variable supersonic ejector, as the throat area ratio increases.

• 한국추진공학회지
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• 제4권4호
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• pp.1-8
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• 2000

본 연구에서는 아음속/초음속 이젝터 시스템의 효과적인 설계를 목적으로, 증기 보일러로부터 발생하는 파열증기를 1차 구동유체로 하는 축대칭 아음속/초음속 이젝터 유동을 실험하였다. 과열증기는 여러형태의 아음속/초음속 노즐에 의하여 이젝터 혼합부로 방출되도록 설계되었으며, 2차정체실 내부에 있는 대기 공기는 증기제트에 의하여 혼합부로 유입된다. 실험에서는 2차정체실의 진공성능을 조사하기 위하여 넓은 범위의 이젝터 자동압력비에 대하여 적용하였다. 본 연구의 결과로부터 이젝터목에서 혼한유동의 정압은 1차 노즐의 형태에 관계없이 이젝터 작동압력비의 함수만에 의하여 결정된다는 것을 알았다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.627-630
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• 2009

이젝터 시스템은 주유동 제트에 발생되는 전단 응력과 압력차에 의해 흡입 챔버 압력에 영향을 미치거나 이차 흡입 유동을 유도한다. 이젝터는 터빈 기반 복합사이클 추진기관 및 로켓엔진의 고고도 모사 설비, 압력회복장치, 담수화 시스템, 이젝터 램젯시스템과 같이 많은 분야에 적용되어 널리 사용된다. 본 연구에서는 아음속 및 음속 조건에서 작동하는 이젝터의 형상 및 운전 조건을 결정하는 설계 절차를 수립하고자 하였다. 또한, 이론적 방법과 시험적 연구를 통해 축소 확대 디퓨저가 장착된 이젝터의 작동 특성을 파악하였다. 결국, 수치해석을 통해 요구 성능을 만족하는 이젝터의 최적 형상을 결정하였으며 다양한 노즐 목 및 챔버 직경을 변화시킨 이젝터에 대한 성능 시험을 통해 계산 결과를 검증하였다.