• Title/Summary/Keyword: In-Cylinder Gas Flow

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Calculation of Pressure Rise in the Puffer Cylinder of EHV GCB Without Arc (무부하시의 초고압 GCB의 파퍼실린더 내부의 상승압력 계산)

  • Park, K.Y.;Song, K.D.;Choi, Y.K.;Shin, Y.J.;Song, W.P.;Kang, J.H.
    • Proceedings of the KIEE Conference
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    • 1994.07b
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    • pp.1559-1561
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    • 1994
  • At present, the principle of puffer action in high current interruption is adopted in almost of the EHV(Extra High Voltage) and UHV(Ultra High Voltage) GCB(Gas Circuit Breakers). The thermal interruption capability of these GCBs critically depends on the pressure rise in the puffer cylinder at current zero. The pressure rise in the puffer cylinder depends on the puffer cylinder volume, flow passage and leakage area in the interrupter, stroke curve etc. Recently commercial CFD(Computational Fluid Dynamics ) packages have been widely adopted to calculate the pressure distribution in the interrupter. However, there are still several problems with it, e.g. very expensive price, moving boundary problem, computation time, difficulty in using the package etc. Thus, the calculation of the puffer cylinder pressure in simple and relatively correct method is essential in early stage of GCB design. In these paper, the model ing technique and computed results for EHV class GCB (HICO, 145kV 40kA and 362kV 40kA GCB) are presented and compared with available measured results.

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A study on the heat transfer of the turbocharged gasoline engine (터보과급 가솔린기관의 열전달에 관한 연구)

  • 최영돈;홍진관
    • Journal of the korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.69-82
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    • 1988
  • Heat transfer experiment is carried out during the performance test of the 4-cylinder 4-stroke cycle turbo-charged gasoline engine. Cycle simulation employing the measured pressure in cylinder, the cooling water temperature and flow rate and others is carried out in order to calculate the gas temperature in cylinder. In this simulation combustion process was simulated by Annand's two zone model and suction, compression, and other processes are calculated completely. From this simulation, we can obtain not only the heat transfer coefficient but also the flame speed, turbulent burning velocity, flame factor and the boiling condition of cooling passage. The results are investigated with engine speed, equivalence ratio and spark advance.

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Numerical Analysis on the Working Fluid Flow of Suction-passage for Reciprocating Compressor (왕복동식 수소압축기의 흡입통로내 작동유체 유동해석)

  • Lee, Gyeong-Hwan;Rahman, Mohammad Shiddiqur;Shim, Kyu-Jin;Jeong, Hyo-Min;Chung, Han-Shik
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.8
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    • pp.1201-1207
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    • 2008
  • Numerical analysis information will be very useful to improve fluid system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas coming to the cylinder of a reciprocating compressor are presented in this paper. Suction-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the Hydrogen system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement, such as reducing the varying flow parameters and flow reorientation should be done. Consequently, development of the better hydrogen compressing system will be achieved.

Safety Evaluation Based on Structural Analysis of Cylinder Valves for Fuel Cell Vehicles (구조해석을 이용한 수소 연료전지 자동차 압력용기 밸브의 안전성 평가)

  • Lee, Hyo Ryeol;Ahn, Jung Hwan;Shin, Jin Oh;Kim, Hwa Young
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.25 no.3
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    • pp.189-197
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    • 2016
  • Green vehicles include electric vehicles, natural gas vehicles, and fuel cell vehicles (FCVs). In FCVs, pressure vessels have cylinder valves to control hydrogen flow. These valves should be of high quality in terms of safety because hydrogen is stored at ultra-high pressure in pressure vessels. Hence, safety evaluation of these valves is necessary to secure the safety of the FCV. A structural analysis of the cylinder valve was conducted in this study by using a commercial finite element analysis code. The results showed that the safety factor of valve component ranged 1.06-186.44. After categorizing, the stress components at critical points of the cylinder valve parts were evaluated using the corresponding allowable design criteria in the ASME code. The pressurization cycle test was performed as per the regulation to evaluate the safety of the valve.

Simulation of Natural Gas Injected Dual-Fuel DI 2-Stroke Diesel Engine (천연가스를 파이럿오일과 이원공급하는 직접분사식 2행정 디이젤기관의 시뮬레이션)

  • Choi, In Su
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.3
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    • pp.9-18
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    • 1995
  • The substitution of conventional fuel oil by alternative fuels is of immense interest due to liquid oil shortage and requirements of emission control standard. Among the alternative fuels, natural gas may be the most rational fuel, because of its widespread resource and clean est burning. Meanwhile, engine simulation is of great importance in engine development. Hence a zero-dimensional combustion model was developed for dual-fuel system. Natural gas was injected directly into the cylinder and small amount of distillate was used to provide the ignition kernel for natural gas burning. The intake air and exhaust gas flow was modeled by filling and emptying method. Although the single zone approach has an inherent limitation, the model showed promise as a predictive tool for engine performance. Its simulation was also made to see how the engine performance was influenced by the fuel injection timings and amount of each fuel.

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Numerical Analysis on the $2^{nd}$ Discharae-passase In Reciprocating Compressor (왕복동식 수소압축기의 2단 토출통로 유동해석)

  • Lee, G.H.;Rahman, M. Sq.;Kim, C.P.;Joung, T.W.;Jeong, H.M.;Chung, H.S.
    • Journal of Power System Engineering
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    • v.13 no.3
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    • pp.27-32
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    • 2009
  • Numerical analysis information of a complex discharge-passage will be very useful to improve hydrogen compression system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas from cylinder going to the chamber of a reciprocating compressor are presented in this paper. Discharge-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the hydrogen compressing system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement should be done. Consequently, development of the better hydrogen compressing system will be achieved.

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Experiment Research of Autonomous Driving Valve for Pulse Detonation Rocket Engine

  • Matsuoka, Ken;Yamaguchi, Hiroyuki;Nemoto, Toyoshi;Yageta, Jun;Kasahara, Jiro;Yajima, Takashi;Kojima, Takayuki
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.419-426
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    • 2008
  • As pulse detonation engine(PDE) does not need compression mechanisms such as compressors because self-sustained detonation waves are able to compress propellant gases by their incident shock waves, the PDE can have a simple straight-tube structure. In this study, we propose an autonomous driving valve system of the PDE, which fill premixed gases into the PDE tubes at high frequency with high mass flow rate. The proposed valve is composed of only three parts: a piston, a cylinder, and a spring. This valve system can produce intermittent flow at high mass flow rate, and also can keep stable reciprocal motion by using the propellant-gas enthalpy. When the cylinder content product is assumed to be constant, experimental results of the mass flow rate were approximately equal to the calculation model. We confirmed the autonomous driving valve performance by experiments, and concluded that this extremely simple valve with no electrical power and controller can be used as the PDE propellant supply system.

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Enhancement of Oxygen Transfer Efficiency Using Vibrating lung Assist Device in In-Vitro Fluid Flow (In-vitro 유동장에서 진동형 폐 보조장치를 이용한 산소전달 효율의 향상)

  • 권대규;김기범;이삼철;정경락;이성철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1332-1335
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    • 2003
  • This paper presents the enhancement of oxygen transfer efficiency using the vibrating intravascular lung assist device (VIVLAD) in in-vitro experiments for patients having chronic respiratory problems. The test section was a cylinder duct with the inner diameter of 30 mm. The flow rate was controlled by the pump and monitored by a built-in flow meter. The vibration apparatus was composed of a piezo-vibrator, a function generator. and a power amplifier. The direction of vibration was radial to the fluid flow. Gas flow rates of up to 6 l/min through the 120-cm-Jong hollow fibers have been achieved by exciting a piezo-vibrator. The output of PVDF sensor were investigated by various frequencies in VIVLAD. The experimental results showed that VIVLAD would be enhance oxygen transfer efficiency.

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Effects of the Flow Characteristics of Helical Intake Port on the Performance and Emission in a Turbocharged DI Diesel Engine. (나선형 흡기포트의 유동특성이 과급식 디젤엔진의 성능 및 배출가스에 미치는 영향)

  • 윤준규;양진승;차경옥
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.5
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    • pp.86-96
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    • 2000
  • This study is to consider that the helical intake port flow and fuel injection system have effects on the characteristics of engine performance and emissions in a turbocharged DI diesel engine of the displacement 9.4L. The swirl ratio for ports was modified by hand-working and measured by impulse torque swirl meter, For the effects on performance and emission, the brake torque, BSFC were measured by engine dynamometer and NOx, smoke were by gas analyzer and smoke meter. As a result of steady flow test, when the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased, And as the swirl is increased, the mean flow coefficient is decreasing, whereas the gulf factor is increasing. Also, through engine test its can be expected to meet performance and emission by the following applied parameter; the swirl ratio is 2.43, injection timing is BTDC $13^{\circ}$CA and compression is 15.5.

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Computational Analysis of Flow Characteristics of a PCV Valve (PCV(Positive Crankcase Ventilation) 밸브의 유동특성에 관한 수치해석)

  • Lee Jong Hoon;Choi Yoon Hwan;Lee Yeon Won
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.4
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    • pp.66-73
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    • 2005
  • A great deal of exhaust gas inside a combustion room goes out through exhaust pipe. But residual gas 'Blowby gas' enters the crankcase through a small gap between the piston and the cylinder wall. Here, if the blowby gas isn't vented, this causes many bad efffcts such as lubricant oil contamination, corrosion by that and crankcase explosion by rising pressure. So most automobiles are constituted with a PCV(Positive Crankcase Ventilation) system to prevent previous problems. PCV valve is the most important part in this ventilation system. When companies are manufacturing new cases, engineers are designing it depending on their experiments than theoretical knowledges. Much efforts and times are needed for new development. This study will show quantitative results to increase the possibilities for the optimal design.