• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.122-129
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• 2008

Rocket Based Combined-Cycle(RBCC) engines are currently being explored as advanced propulsion for space transportation. JAXA has been conducting RBCC engine research by using various experimental facilities. In order to clarify the experimental results and contribute to the improvement of designing, the analysis of the RBCC engine in an ejector-jet mode was carried out using the CFD code developed in-house for unstructured grids. CFD replicated the characteristic flow structures. The numerical simulation of the pumping performance of the ejector driven by different rocket gases(He, $N_2,\;A_r$) and physical conditions were performed, and their effects on the performance were studied.

• 한국분무공학회지
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• 제27권3호
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• pp.126-133
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• 2022

The objective of this is to experimentally investigate the effect of mixed jet on the oxygen transfer characteristics with the primary nozzle area ratio of an annular nozzle ejector for the application of a microbial fuel cell. A direct visualization method with a high speed camera system was used to capture the horizontal mixed jet images, and a binarization technique was used to analyze the images. The clean water unsteady state technique was used for the oxygen transfer measurement. The air-water mixed jet discharging into a water tank behaved similar to a buoyancy or horizontal jet with the primary nozzle area ratio. It was found that an optimum primary nozzle area ratio was observed where the oxygen transfer performance reached its maximum value due to the decrease of air volume fraction and the increase of jet length and air bubble dispersion.

• 한국분무공학회지
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• 제3권2호
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• pp.14-23
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• 1998

The negative pressure as much as 10's mmHg is demanded at nozzle inside, in case of atomizing the large density molten materials. by conventional air jet nozzle. In this study, suction type fluid nozzle is designed by applying the ejector principle in order to clarify the air flow of nozzle inside, mechanism of liquid suction and liquid film formation. The results of this experimental study areas follows. Suction force of liquid is magnified by using liquid nozzle, and it is able to supply the liquid stable. Negative pressure at nozzle inside is varied by throttle angle of liquid nozzle, position and outer diameter of air jet nozzle, and have a influence on liquid suction quantity and liquid film formation.

• 한국태양에너지학회 논문집
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• 제30권6호
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• pp.137-143
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• 2010

In this study, the ejector design was modeled using Fluent 6.3 of FVM(Finite Volume Method) CFD(Computational Fluid Dynamics) techniques to resolve the flow dynamics in the ejector. A vacuum system with the ejector has been widely used because of its simple construction and easy maintenance. Ejector is the main part of the desalination system, of which designs determine the efficiency of system. The effects of the ejector was investigated geometry and the operating conditions in the hydraulic characteristics. The ejector consists mainly of a nozzle, suction chamber, mixing tube(throat), diffuser and draft tube. Liquid is supplied to the ejector nozzle, the fast liquid jet produced by the nozzle entrains and the non condensable gas was sucked into the mixing tube. In the present study, the multiphase CFD modeling was carried out to determine the hydrodynamic characteristics of seawater-air ejector. Two-dimensional geometry was considered with the quadrilateral-mashing scheme. The gas suction rate increases with increasing Motive flow circulating rate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.856-860
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• 2000

Liquid ejector is widely used for power plant water pump, marine pump and transportation of solid materials. It has high working confidence and simple configuration. However, It is not easy to know performance degradation of ejectors in field. When the geometry of ejector is complicate, the diagnosis of faults is required more skillful method without disassemble. This paper gives numerical method to predict cause of $45^{\circ}$ slurry suction ejector performance degradation.

• 한국가시화정보학회지
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• 제9권4호
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• pp.47-53
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• 2011

A water driven ejector loop was designed and constructed for air absorption. The used ejector was horizontally installed in the loop and annular water jet at the throat entrained air through the circular pipe placed at the center of the ejector. Wide range of water flow rate was provided using two kinds of pumps in the loop. The tested range of water flow rate was 100${\ell}$ /min to 1,000 ${\ell}$/min. Two-phase flow inside the ejector loop was simulated by CFD analysis. Homogeneous particle model was used for void fraction prediction. Water and air flow rates and pressure drop through the ejector were automatically recorded by using the LabView based data acquisition system. Flow characteristics and air bubble velocity field downstream of the ejector were investigated by two-phase flow visualization and PIV measurement based on bubble shadow images. Overall performance of the two-phase ejector predicted by the CFD simulation agrees well with that of the experiment.

• 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 2011년도 제37회 추계학술대회논문집
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• pp.705-708
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• 2011

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 다양한 고고도 환경 모사를 위한 멀티 이젝터의 형상 및 운전 조건을 결정하는 설계 절차를 수립하고자 하였다.

• 대한기계학회논문집B
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• 제37권9호
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• pp.847-854
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• 2013

본 연구는 환형 노즐 이젝터를 이용하여 수평방향 폭기공정의 혼합유동 및 산소전달 특성에 대한 실험적 연구를 목표로 한다. 실험변수는 이젝터 피치와 가압수 유량이며, 측정된 유량과 압력을 이용하여 유량비, 수두비 및 효율을 계산하였다. 이적터에서 분출된 혼합유동의 가시화를 통해 정성적 거동을 고찰하였으며, 용존산소량을 측정하여 총괄 산소전달계수를 도출하였다. 이젝터에서 분출된 혼합유동은 가압수의 운동량과 유입된 공기기포의 미립화에 따라 부력분류 또는 수평분류의 거동을 나타내었다. 기포의 크기에 기인하는 부력과 가압수의 운동량에 지배되는 혼합유동의 도달거리는 가압수와 공기기포의 접촉 면적 및 시간에 크게 영향을 미치기 때문에 산소전달률의 중요한 변수임을 유추할 수 있다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.749-754
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• 2006

This study performed of a water cooling system by using a steam ejector and jet condenser to drop the temperature of the water in aquafarm by about $5^{\circ}C$ from $25^{\circ}C$ or higher in this research, to replace the present water cooling system, Ive focused on a water cooling system operated by latent heat of evaporation, thus this system needs a vacuum pressure to evaporate the water in enclosed tank. The water cooling effects are dependent on the vacuum pressure in the enclosed tank, and the cooling water is generated by evaporation. As the experimental results, the absolute vacuum pressure obtained was about $5{\sim}8mmHg$ using a steam driven ejector with jet condenser in experiments. The obtained results are respectively ${\Delta}T=7^{\circ}C$, ${\Delta}T=5^{\circ}C$ and ${\Delta}T=5.5^{\circ}C$ at heat exchanger flow rate 4L/M. The obtained results are respectively ${\Delta}T=5.5^{\circ}C$, ${\Delta}T=5.5^{\circ}C$ and ${\Delta}T=5.5^{\circ}C$ at heat exchanger flow rate 4.5L/M.