• Title/Summary/Keyword: Ejector-jet

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INTERNAL FLOW PROPERTIES AND THRUST CHARACTERISTICS OF AXI-SYMMETRIC ANNULAR BELL TYPE EJECTOR-JET (축대칭 환형 이젝터 제트의 내부 유동과 추력특성)

  • Park, G.H.;Kwon, S.J.
    • Journal of computational fluids engineering
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    • v.12 no.2
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    • pp.46-52
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    • 2007
  • An experimental and numerical investigation of the ejector-jets focusing on its geometric parameters that effect on thrust performance was carried out. The area ratio of the primary nozzle that was tested in the present study was 2.17 and 3.18, while the ratio of the length to the diameter of the duct downstream the primary nozzle inlet had values of 3.41, 6.82, and 10.23. Internal flow properties of ejector-jet were estimated by comparison experiment data and CFD analysis for basic study of ejector-jet thrust performance. For examination of thrust performance, the thrust ratios increased with increase in L/D. Especially at AR=2.17, the maximum thrust augmentation was 33 percent for the shortest L/D. It is expected that the increase of mixing duct length of ejector-jet will be helpful in a thrust performance by improving mixing efficiency.

INTERNAL FLOW PROPERTIES AND THRUST CHARACTERISTICS OF AXI-SYMMETRIC ANNULAR BELL TYPE EJECTOR-JET (축대칭 환형 이젝터 제트의 내부 유동과 추력특성)

  • Park, G.H.;Kwon, S.J.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.04a
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    • pp.166-170
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    • 2007
  • An experimental and numerical investigation of the ejector-jets focusing on its geometric parameters that effect on thrust performance was carried out. The area ratio of the primary nozzle that was tested in the present studywas 2.17 and 3.18, while the ratio of the length to the diameter of the duct downstream the primary nozzle inlet had values of 3.41, 6.82, and 10.23. Internal flow properties of ejector-jet were estimated by comparison experiment data and CFD analysis for basic study of ejector-jet thrust performance. For examination of thrust performance, the thrust ratios increased with increase in L/D. Especially at AR=2.17, the maximum thrust augmentation was 34 percent for the shortest L/D. It is expected that the increase of mixing duct length of ejector-jet will be helpful in a thrust performance by improving mixing efficiency.

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A Study on the Comparison of Design Conditions between Booster Ejector and Air Ejector in the Steam-Jet Water-Vapour Refrigeration Cycle (증기분사냉동계의 부우스터 이젝터와 에어 이젝터의 설계조건비교에 관한 연구)

  • Lee, Chang-Sik
    • The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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    • v.7 no.2
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    • pp.73-79
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    • 1978
  • This paper presents the experimental study on the design conditions of pressure between booster ejector and air ejector in the steam-jet water-vapour refrigeration system. In this experiment, the motive steam of booster ejector and ai. ejector was dry saturated from 6 ata to 8 ata and flash chamber pressure were about $10\∼540mmHg$ higher than mixing section in booster ejector. The investigation of air on the pressure of booster ejector was performed by changing the condenser pressure. The experimental results show that flash chamber vacuum and condenser pressure of steam-jet refrigeration cycle increased in accordance with the increase of motive steam Pressure. Among the several nozzle sires tested, No.4 nozzle were best in term of evaporator vacuum under the constant operating conditions of air ejector in condenser.

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A Study on the Performance Characteristics of Air Driven Gas Ejector (공기구동 기체이젝터의 성능특성에 관한 연구)

  • 홍영표;윤두호;김용모;윤석훈
    • Journal of Advanced Marine Engineering and Technology
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    • v.18 no.1
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    • pp.51-59
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    • 1994
  • The gas jet pumps serve to preduce a vacuum or can be used as gas jet compressors. These are operated on the same principle as a steam jet vacuum pump : in the driving nozzle the pressure energy of the motive medium is converted into the kinetic energy. In the diffuser the driving jet mixes with the suction medium and the kinetic energy is reconverted into the pressure enegy. The application fields of gas jet ejectors are the evacuation of siphoning installations, the elevation of liquids, the production of vacuum filters, the vacuum supporting airlift system, the evacuation of the suction line of centrifugal pumps and the ventilation of the dangerous gases to the atmosphere. The performance of gas jet ejector is influenced strongly to velocity coefficient of motive nozzle, the distance between the motive outlet to the diffuser inlet and the dimensions of diffuser. This study is performed for the computer aided design of gas jet ejectors in future. Through the present experiments, it is known that the velocity coefficient of the motive air nozzle ranges from 0.91 to 0.95 and the maximum efficiency of gas jet ejector is 24.6%.

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A NUMERICAL STUDIES ON THE FLOW PROPERTIES OF AXI-SYMMETRIC ANNULAR BELL TYPE EJECTOR-JETS (축대칭 환형 분사식 이젝터 제트 유동 특성의 수치적 연구)

  • Park, G.H.;Kwon, S.J.
    • 한국전산유체공학회:학술대회논문집
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    • 2006.10a
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    • pp.185-188
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    • 2006
  • An investigation of the ejector-jets focusing on its flow properties was carried out by varying the geometric parameters. The area ratio of the primary nozzle, AR that was tested in the present measurement was 2.17 and 3.18, while the ratio of the length to the diameter of the duct downstream the primary nozzle inlet, L/D had values of 3.41, 6.82, and 10.23. For the frame work of flow characteristics, the wall pressures distribution of ejector-jet was investigated by experiment for basic study of ejector-jet performance. In result, terminal shock location and existence of series of oblique shocks are recognized. In this study, CFD analysis was conducted at the same time. And as a result of comparison experiment data with CFD analysis, the physical phenomena of ejector-jets were estimated.

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A Study of the Transient Flow Characteristics of a Vacuum Ejector-Diffuser System.

  • Rajesh, G.;Kim, H.D.
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2769-2774
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    • 2007
  • In vacuum ejector-diffuser systems where a finite volume secondary chamber is used, the secondary jet exhibits transient characteristics during start-up. A steady state is achieved after some time in which mass entrainment prevails indefinitely inside the ejector, though there is no flow from the secondary chamber. An attempt is made in this work to study the infinite entrainment of secondary jet into the primary jet from a finite secondary chamber, with the help of a computational fluid dynamics method. The present study is also intended to identify the operating range of vacuum ejector-diffuser systems where the steady flow assumption can be applied without uncertainty. The results obtained show that the only condition in which an infinite mass entrainment is possible is the generation of a re-circulation zone near the primary nozzle exit. The flow in the secondary chamber attains a state of dynamic equilibrium at this point. Steady flow assumption is valid only after this point.

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A Study on Flow Characteristics of Ejector for Cyclone Air Drying Machine (사이클론 건조기용 이젝터 유동 특성에 관한 연구)

  • Kim, Bong-Hwan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.11 no.6
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    • pp.189-194
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    • 2012
  • The purpose of this study is to predict the performance of a cyclone drying machine and air ejector used in drying applications. This paper deals with optimization of the geometry of the ejector for sludge drying using computational fluid dynamics. To facilitate the design of a jet ejector for air drying machines, a numerical model of simultaneous mass and heat transfers between the liquid(sludge) and gas(air) phases in the jet ejector was developed. The steady-state model was based on unidimensional balance equations of mass, energy and momentum for the liquid and gas phases. It was shown that the optimum condition to minimize pressure and momentum loss of air in the ejector was d=220mm. It was found that sludge particles inside the cyclone was smoothly discharged by the conical wedge installed on the bottom of the cyclone.

Basic Investigation for the Development of Cleaning Technology with Ejector (이젝터를 이용한 세정기술 개발의 기초연구)

  • Park, Sang Kyoo;Yang, Hei Cheon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.41 no.1
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    • pp.29-36
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    • 2017
  • The paper presents a basic investigation for the development of cleaning technology employing an annular nozzle ejector for application to cleaning water supply and air bubble generation. The quantitative flow characteristics of the primary and suction flows, the qualitative visualization behavior of the mixed jet, and the percentage concentration of pesticide residual at different values of the ejector screw pitch were investigated. It was seen that the primary flow rate increased, while the mass ratio decreased with increase in screw pitch. Further, the mixed jet behaved like a buoyancy jet or horizontal bubbly jet, and the residual concentration of pesticide first decreased and then increased with increase in screw pitch.

An Experimental Study of the Subsonic/Supersonic Steam Ejectors (아음속/초음속 증기 이젝터에 관한 실험적 연구)

  • Kim, Heuy-Dong;Choi, Bo-Gyu;Lee, Jun-Hee
    • Proceedings of the KSME Conference
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    • 2000.11b
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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.

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Study on Cooling Charcteristics of Forced Evaporation by using Steam Ejector (스팀 에젝터에 의한 강제 증발 방식의 냉각 특성에 관한 연구)

  • Son, H.J.;Lee, Y.H.;Kim, Y.G.;Jeong, H.M
    • Journal of Power System Engineering
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    • v.10 no.2
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    • pp.41-46
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    • 2006
  • This study shows a water cooling system by using a steam ejector and jet condenser to drop the temperature of the water by about $5^{\circ}C\;from\;25^{\circ}C$ or higher. In this research, to replace the present water cooling system, we focused on a water cooling system by latent heat of evaporation, thus this system needs a vacuum pressure to evaporate the water in enclosed tank. The water cooling effects are depended on the vacuum pressure in the enclosed tank, and the cooling water is generated by latent head of evaporation. As the experimental results, the absolute vacuum pressure obtained was about $5{\sim}8$ mmHg using a steam driven ejector with jet condenser.

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