• Title/Summary/Keyword: Throat ratio

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An Experimental Study of the Variable Sonic/supersonic Ejector Systems (가변형 음속/초음속 이젝터 시스템에 관한 실험적 연구)

  • Lee Jun Hee;Kim Heuy Dong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.5 s.236
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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.

An Experimental Study on the Variable Sonic Ejector System (가변형 음속 이젝터 시스템에 관한 실험적 연구)

  • Lee, Jun-Hee;Jung, Sung-Jae;Kim, Heuy-Dong;Koo, Byoung-Soo
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.2035-2040
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    • 2004
  • A cone cylinder is used to obtain variable operation conditions for the sonic ejector-diffuser system. The cone cylinder is designed to move upstream and downstream to change the ejector throat area ratio, thus obtaining variable mass flow rates. The present study investigates the effects of ejector throat area ratio and operating pressure ratio on the entrainment of secondary stream for the variable sonic ejector system. In experiment, the ejector throat area is varied in the range from ${\psi}=11.88$ to 66.69, and the operating pressure ratio from $p_{0p}/p_a=1.25$ to 9.0. The results show that the variable sonic ejector system is suitable for a required entrainment ratio of secondary stream by altering the ejector throat area ratio and operating pressure ratio.

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A Study of a Variable Sonic Ejector Flow

  • Lee, Jun-Hee;Kim, Heuy-Dong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.03a
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    • pp.414-417
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    • 2004
  • A cone cylinder is used to obtain variable operation conditions for the sonic ejector-diffuser system. The cone cylinder is designed to be shifted upstream and downstream to change the ejector throat area ratio, thus obtaining variable mass flow rates. The present study investigates the effects of ejector throat area ratio and operating pressure ratio on the entrainment of secondary stream for the variable sonic ejector system. The study is carried out experimentally. The ejector throat area is varied at the range from Ψ= 11.88 to 66.69, and the operating pressure ratio is changed from $P_{op}$ / $P_{a}$=1.25 to 9.0. The results show that the variable sonic ejector system can be operated to obtain specific entrainment ratio of secondary stream by altering the ejector throat area ratio and operating pressure ratio.o.

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Improving Compression and Throat Ratios of Combustion Chamber for Reduction of Exhaust Emissions for a Swirl Chamber Type Diesel Engine (와류실식 디젤기관의 배기배출물 저감을 위한 연소실의 압축비 및 분구면적비 개선)

  • Lee, Chang-Kyu;Huh, Yun-Kun;Seo, Sin-Won
    • Korean Journal of Agricultural Science
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    • v.37 no.3
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    • pp.501-508
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    • 2010
  • A swirl chamber type diesel engine attachable to 18 kW agricultural tractors was improved to reduce exhaust emissions. Compression ratio and throat area ratio of the combustion chamber were varied to determine optimum combustion conditions. Tests were composed of full load and 8-mode emission tests. Compression ratio was fixed as 21, but the swirl chamber volume was increased by 3.8%. Output power, torque, specific fuel consumption, exhaust gas temperature, and smoke level were not considerably different for compression ratios of 21.5 (reference condition) and 21 (test condition), while NOx, HC, CO and PM levels for the compression ratio of 21 were decreased by 11%, 46%, 28%, 11%, respectively, from those for the compression ratio of 21.5. The tests were also conducted with a compression ratio of 22 and 4.3% increased chamber volume. Output power, torque, exhaust gas temperature and smoke level were greater, while specific fuel consumption was less for the compression ratio of 22 than those for the compression ratio of 21.5. Increase of compression ratio decreased HC and CO levels by 24%, 39%, but increased NOx and PM levels by 24%, 39%. Based on these results, a compression ratio of 21 was selected as an optimum value. Then, full load tests with the selected compression ratio of 21 were carried out for different throat ratios of 1.0%, 1.1%, 1.2%. Output power and torque were greatest and smoke was lowest when throat area ratio was 1.1%, which satisfied the target values of specific fuel consumption (less than 272 g/$kW{\cdot}h$) and exhaust gas temperature (less than $550^{\circ}C$). Therefore, a throat area ratio of 1.1% was selected as an optimum value.

A Computational Study of a Variable Sonic Ejector Flow (가변형 음속 이젝터 유동에 관한 수치해석적 연구)

  • Lee, Jun-Hee;Choi, Bo-Gyu;Kim, Heuy-Dong
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.526-531
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    • 2003
  • A cone cylinder is used to obtain variable operation conditions of a sonic ejector-diffuser system. The cone cylinder is movable to change the ejector area ratio, thus obtaining variable mass flow rates. The present study investigates the effects of ejector throat area ratio and operating pressure ratio on the entrainment of secondary stream. The numerical simulations are based on a fully implicit finite volume scheme of the compressible, Reynolds-Averaged, Navier-Stokes equations. The ejector throat area is varied between 3.94 and 8.05, and the operating pressure ratio is changed from 3.0 to 9.0. The results show that the entrainment ratio and mass flux ratio become more dependent on the ejector throat area ratio, when the pressure operating ratio is low. The total pressure losses produced in the present ejector system increase with the operating pressure ratio and the ejector area ratio, but for a given operating pressure ratio, the losses are not significantly dependent on the ejector area ratio when it is larger than about 5.0.

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An Experimental Study on Flow in the Nozzle of a Radial Turbine (구심터빈의 노즐 내부 유동에 대한 시험 연구)

  • Kang, Jeong-Seek;Lim, Byeung-Jun;Ahn, Iee-Ki
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.1
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    • pp.35-41
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    • 2010
  • Experimental study on the flow field inside the nozzle for radial turbine was performed. At design point, the pressure is high and the Mach number is low at the pressure side of the nozzle inlet semi-vaneless space as the flow turns through the nozzle vanes. As the flow accelerates through the nozzle passage to the throat the pressure level at the pressure and suction sides becomes similar. The flow continued accelerating from the throat to the inlet of turbine wheel and the pressure field became uniform in the circumferential direction in the vaneless space. In high expansion ratio condition, strong favorable pressure gradient band region occurred just after the throat in the semi-vaneless space in the circumferential direction and the pressure became uniform in the circumferential direction after this band. In low expansion ratio condition, core flow acceleration is dominant after the throat and this non-uniform pressure field reached to the inlet of turbine wheel.

Three Dimensional Simulation Model of Fuel Delivery Jet Pump (연료 송출용 제트펌프 3차원 전산해석 모델)

  • PARK, DAIN;YUN, JIN WON;YU, SANGSEOK
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.3
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    • pp.308-314
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    • 2017
  • Jet pump in automotive fuel tank module is used to deliver fuel to fuel pump so that the pump is operated without aeration in suction side. In this study, three dimensional simulation model of jet pump is developed to understand performance variation over design parameters. Performance of jet pump is also investigated experimentally in terms of operating pressures. The experimental data is used to verify the three dimensional simulation model of jet pump. Verification results show that the three dimensional simulation model of jet pump is about 1% error with experiment. The simulations are conducted in terms of throat ratio and primary flow induction angle. As the throat ratio is increased, the flux ratio is trade-off at 3 times of throat diameter. On the other hand, as primary flow induction angle is increased, vapor pressure inside the nozzle is decreased. In summary, the results show that liquid jet pump has to be optimized over design parameters. Additionally, high velocity of induced flow is able to evolve cavitation phenomena inside the jet pump.

A Study on the Characteristics of the Liquid-gas Ejector (Liguid-gas Ejector의 구동성능 특성에 관한 연구)

  • Park, Gi-Tae;Jin, Zhen-Hua;Chung, Han-Shik;Jeong, Hyo-Min
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.1047-1052
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    • 2008
  • The aim of this paper is that studies on the characteristics of the liquid-gas ejector. Could get data about various model using numerical analysis. Compare and analyze result that get by an experiment and numerical analysis. And studied Characteristics of the ejector. In this paper, Numerical analysis model is gotten divided according to each Throat ratio as three types. Each throat ratio is 0, 4 and 7.5. According to the result that analyze basic model, pressure became lower causing the volume flow rate increase. In CFD studies, Fixed volume flow rate by these result and analyzed ejector performance. As a result, there was no change of pressure to Throat's Enterance, and pressure became low while pass the throat. Since, pressure recovered while passing diffuser. The outer flow velocity did not change greatly to change of volume flow rate. This research expects that is utilized to data for performance elevation hereafter.

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The Comparison of Experimental Results of Liquid Ejector Performance to Predictions by the Computer Aided Design Program (液休용 이젝터 性能에 관한 CAD와 實驗結果와의 比較)

  • 김경근;김명환;홍영표;고상철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.3
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    • pp.520-527
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    • 1988
  • Liquid ejectors are widely used as marine pumps, inducer stage for the boiler feed water pump, boiler recirculating pump, cooling water recirculating pump in boiling water type nuclear reactor and a deep well pump, because of their high working confidence and simplicity. Furthermore, it requires only a modest net positive suction head for cavitation-free operation and it can be installed in remote location from mechanical power source. It is not easy to presume the friction losses, because it is complicately affected by area ratio, flowrate ratio, nozzle spacing, throat length, shape of liquid ejector and so on. Therefore, the optimization of liquid ejector design is still dependent, to a large extent, on the experimental results and empirical procedures. On the design of the liquid ejector, the area ratio and the nondimensional throat length are the most important design factors among the mentioned above. In this experiment, the effects of the area ratio and the nondimensional throat length to ejector efficiency are carried out systematically by the combination of 4 kinds of motive nozzle and 2 kinds of throat length. In this paper, the present experimental results are compared with the calculated ones by the previous computer aided design program based on one dimensional flow equation. And also, an empirical equation for the working limit of liquid ejector is reported.

Estimation Methods for Turbine Nozzle Throat Area Reduction of A LOx/Kerosene Gas Generator Cycle Liquid Propellant Rocket Engine (액체산소/케로신 가스발생기 사이클 액체로켓엔진 터빈 노즐목 면적 변화 추정 방법)

  • Nam, Chang-Ho;Moon, Yoonwan;Park, Soon Young;Kim, Jinhan
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.5
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    • pp.101-106
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    • 2019
  • Carbon deposition on the turbine nozzle throat of a LOx/kerosene gas generator cycle(open cycle) engine causes performance reduction of the engine. Estimation methods for a turbine nozzle throat area are proposed. The discharge coefficient of the turbine nozzle was estimated with the turbine gas properties such as gas constant, specific heat ratio, and temperatures. The pressure ratio and temperature ratio of the turbine nozzle throat, was utilized to estimate the discharge coefficient also. Estimated discharge coefficient of turbine nozzle throat of KSLV-II 1st stage engine shows the carbon deposition effects on the turbine nozzle throat of a LOx/kerosene open cycle engine.