• Title/Summary/Keyword: Pressure-rise rate

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A Study on the Performance Prediction of Automotive Water Pump with Double Discharge Single Suction (자동차용 양토출 단흡입 워터펌프의 성능 예측에 관한 연구)

  • 허형석;박경석;이기수;원종필
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.3
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    • pp.27-36
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    • 2004
  • A Numerical analysis has been used to predict the performance in the automotive water pump with double discharge single suction. The influence of parameters such as coolant flow rate, rotational speed, ratio of blade height and clearance has been investigated. Also, the prediction of hydraulic performances such as static pressure rise, shaft power, hydraulic power and pump efficiency is carried out on the water pump including an impeller and a volute casing. A full size water pump test bench has been developed to validate the CFD flow model. Discharge flow rate, suction pressure, discharge pressure, rotational speed and torque measurements are provided. Coolant temperature is 8$0^{\circ}C$, water tank pressure is 1 kgf/$\textrm{cm}^2$ and flow rates vary.

An Experimental Study on the Performance of Turbocharged Diesel Engine (터보과급 디이젤기관의 성능에 관한 실험적 연구)

  • Chae, J.O.;Chung, S.C.;Baek, J.H.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.6
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    • pp.76-86
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    • 1994
  • Combustion of diesel engine depends on the mixing of air and evaporating fuel during ignition delay greatly. Variation of air-fuel mixing rate and ignition delay for engine operating condition causes difference of combustion, performance and exhaust emissions. This study is investigated in a turbocharged diesel engine of IDI swirl chamber type. In the results, As injection timing is advanced until $12.6^{\circ}$ BTC, ignition delay decreases. NOx concentration and smoke level in exhaust gas increases for advanced injection timing Ignition delay, combustion period, pressure rise rate and exhaust gas temperature are increased with increasing engine speed. And ignition delay at high load is more decreased than that at low load. Ignition delay and combustion period are decreased with increasing intake pressure. Power increases, temperature and CO, NOx concentration in exhaust gas decreases as intake pressure increases. With increasing load, ignition delay is decreased and combustion period, motoring pressure are increased.

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Study on the dynamics of capillary rise between elastic sheets (탄성박판간의 모세관 상승운동에 관한 연구)

  • Ahn, Won-Jin;Kim, Ho-Young
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2743-2746
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    • 2007
  • When a small tube is dipped into a liquid surface, surface tension forces cause the liquid in the tube to rise vertically against the gravity. When the tube is flexible, hydrostatic pressure difference caused by the capillary flow deforms the tube and the deformation which narrows the flow route changes the rising velocity. We study a simple model of this elastocapillary interaction in the context of the surface-tension-driven vertical rise of a liquid between two long flexible hydrophilic sheets that are held a small distance apart at one end. We provide an analytical theory for the rise rate of the liquid and show that our experiments are consistent with the theory.

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A Study on Minimizing of Condenser Pressure Loss according to the Temperature Rise of the Seawater for Korean Standard Coal-fired Power Plants (표준석탄화력 발전소 해수온도 상승에 따른 복수기 압력 손실 최소화 방안)

  • An, Hyo-Yoel;Moon, Seung-Jae
    • Plant Journal
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    • v.11 no.2
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    • pp.45-51
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    • 2015
  • In this paper, studied condenser operating management which is affecting power plants efficiency considering the cost of poor quality. Sea water temperature and condenser pressure have clear correlation in S power plants. As the sea water temperature changes, condenser pressure changed -1.7~+20 mmHg from design condenser pressure(38.1 mmHg). Use the heat rate correction curve from manufactory company, realized that efficiency and cost of poor quality changed 0.0201%, 12,830 won/h at Unit #1,2 but 0.0155%, 9,832 won/h when condenser pressure 1 mmHg rise. Also, checked that it is changed depend on seasonal corresponding operation, plant ageing and the point of preventive maintenance like overhaul maintenance. This study said if we considered complying with management range and planning overhaul maintenance, then it could help reducing operating maintenance losses minimum 2.5 billion won per 1 year (case : Unit #1, forty days maintenance).

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Analysis of fast pressure control by the Ziegler-Nichols method for a transport module of a high vacuum cluster tool (고진공 클러스터 장비의 반송모듈에 적용된 Ziegler-Nichols 방법에 의한 고속 압력제어에 관한 해석)

  • 장원익;이종현;백종태
    • Journal of the Korean Vacuum Society
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    • v.5 no.4
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    • pp.284-291
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    • 1996
  • We have implemented a fast pressure control system for the transport chamber of a high vacuum cluster tool for advance semiconductor fabrication and evaluated its performance. To overcome the typically slow response of mass flow controllers, the modified experimental method is used very effectively to optimize the pressure control procedure. We successfully obtained quite fast pressure control by adjusting the starting time and eht tuning constants by the Ziegler-Nichols method. In the transport pressure $10\times 10^{-5}$ torr, actual pressure control starts from 4 sec after an initial gas load of 2.1 sccm. As a result, optimum conditions for the tuning constants are the rise rate of 0.02 torr/sec, the lag time of 0.15 sec, and the sampling period of 0.5 sec. Then the settling time is about 9 sec within about $\pm$0.5% for the referenced value. This settling time is enhanced above 75 percents in comparison with conventional experimental method. To account for the experimental effects observed, a theoretical model was developed. This experimental result has a tendency to fit with the theoretical result of $\omega$=-1.0.

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Effect of Pressure on Acoustic Pressure Response and NO Formation in Diluted Hydrogen-Air Diffusion Flames (희석된 수소-공기 확산 화염에서 음향파 응답과 NO 생성에 미치는 압력의 영향)

  • Sohn, Chae-Hoon;Chung, Suk-Ho
    • 한국연소학회:학술대회논문집
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    • 1999.10a
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    • pp.11-20
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    • 1999
  • Acoustic pressure response and NO formation of hydrogen-air diffusion flames at various pressures are numerically studied by employing counterflow diffusion flame as a model flame let in turbulent flames in combustion chambers. The numerical results show that extinction strain rate increases linearly with pressure and then decreases, and increases again at high pressures. Thus, flames are classified into three pressure regimes. Such non-monotonic behavior is caused by the change in chemical kinetic behavior as pressure rises. Acoustic pressure response in each regime is investigated based on the Rayleigh criterion. At low pressures, pressure-rise causes the increase in flame temperature and chain branching/recombination reaction rates, resulting in increased heat release. Therefore, amplification in pressure oscillation is predicted. Similar phenomena are predicted at high pressures. At moderate pressures, weak amplification is predicted. Emission index of NO shows similar behaviors as to the peak-temperature variation with pressure.

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Total Pressure Loss in a Supersonic Nozzle Flow with Condensation (凝縮을 隨伴하는 超音速 노즐흐름의 全壓損失)

  • 강창수;권순범
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.3
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    • pp.582-589
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    • 1988
  • A rapid expansion of moist air or steam in a supersonic nozzle gives rise to condensation, and the total pressure of the flow is decreased due to this irreversibility of condensation phenomenon. In the present paper, the loss in total pressure during the condensation process has been studied, by numerical analysis and pressure measurement, in the case of moist air expanding in a supersonic nozzle. The effects of the degree of supersaturation at the stagnation condition and expansion rate of the nozzle on the total pressure loss have been studied. The length of the region where the total pressure decreases during the condensation process is longer than that of the nonequilibrium condensation region, and of difference between the length of these two increases with the increase of the degree of supersaturation at the stagnation condition. Furthermore, the larger the expansion rate of the nozzle and the higher the temperature and the degree of supersaturation at the reservoir are, the larger the total pressure loss of the flow becomes. And, it is turned out that the total pressure loss be about 2 to 8 percent in the present study.

A study on the microcomputer aided pressure progress measurement and combustion analysis in engine cylinder (Micro-Computer를 이용한 기관 실린더 내의 압력측정 및 연소해석에 관한 연구)

  • 김희년;김시범;하종율
    • Journal of the korean Society of Automotive Engineers
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    • v.10 no.3
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    • pp.45-50
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    • 1988
  • The measurement system of the pressure in engine cylinder is developed with the aids of the microcomputer, A/D converter and simple electrical circuits. The experiment is performed in 4 cycle single cylinder Gasoline engine. When data for the pressure progress is sampled, clock signal or signal from the crank angle is used as trigger. The variation of the pressure during the cycles can be well obtained experimentally. So, the informations which are necessary in the combustion analysis, i.e. expansion pressure, indicated mean effective pressure, the magnitude and time of the maximum pressure ignition time, the rate of pressure rise and heat release and combustion rates can be obtained by the calculation using experimental data. Also, the informations about the after-burning process, the existence of the detonation waves and end time of combustion can be investigated from this study.

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Study on Leak Detection of the Pipeline System by Acoustic Emission (음향방출(音響放出)에 의한 배관계(配管系)의 누출방지(漏出防止)에 관한 연구(硏究))

  • Yoon, D.J.;Kim, C.J.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.7 no.1
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    • pp.7-17
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    • 1987
  • Leak detection testing for the pipeline system was performed by the acoustic emission method. It was found that the detected signal spectrum was influenced by the frequency response of sensors and pressure changes. AE parameters and frequency spectrum distributions were used to analyze the leak signals. The slope rise time of AE parameters were the important factors for distinguishing leak signals. The amplitude of leak signal was more affected by the changes of leak, rate and pressure than those of leak type.

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Design of Low Noise Axial-Tube Fan (저소음 축류형 소형홴의 개발)

  • Kim, K.-H.;Lee, S.;Kim, B.-H.
    • 유체기계공업학회:학술대회논문집
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    • 2001.11a
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    • pp.17-22
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    • 2001
  • Tube axial fans were designed to provide effective cooling for a personal computer by using $DasignFan^{TM}$ software. With basic input parameters of flow rate, pressure rise, rotating speed, and fan diameter, three dimensional geometry of blade is automatically generated and its performance and overall sound pressure level are predicted. In this steady, the newly developed fans of 60 mm and 80 mm diameters were proved to provide a very promising mode of low noise, compared with manufactured products.

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