• 제목/요약/키워드: Valve Opening Characteristics

검색결과 175건 처리시간 0.026초

흡기포트압력을 이용한 SI엔진의 체적효율 및 토크 성능 분석 (Analysis on Volumetric Efficiency and Torque Characteristics Using Inlet Port Pressure in SI Engines)

  • 이영주;홍성준
    • 대한기계학회논문집
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    • 제16권7호
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    • pp.1408-1418
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    • 1992
  • 본 연구에서는 여러가지 흡기관 조건 및 밸브타이밍 변화에 대하여, 현재까지 연구에서 확인된 IVC에서 흡기포트압력 값의 체적효율에 대한 영향을 검토하고, 흡기 밸브가 열리는 동안 흡기 포트압력의 어느 부분 또는 지점이 엔진의 체적효율 변화를 설명해 줄 수가 있는지를 실험적으로 규명하고자 하였다.이 목적을 위해 각 흡입조 건에 대한 흡기포트압력 및 엔진 성능값을 측정.분석하여 서로의 연관성을 비교, 검토 하였다.

증기발전 시스템의 과도상태 특성 해석 (Analysis of Transient Characteristics of a Steam Power Plant System)

  • 박근한;김동섭;노승탁
    • 대한기계학회논문집B
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    • 제24권7호
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    • pp.967-975
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    • 2000
  • Transient characteristics of a boiler and turbine system for a steam power plant are simulated. One-dimensional unsteady models are introduced for each component. An interaction between boiler and turbine and a control of the water level in the drum are taken into account. Transient responses of the system to the variations of main system variables such as fuel and air flow rate, cooling water injection rate at the attemperator, gas recirculation rate at the furnace and opening of the turbine control valve are examined. Effect of fluid inertia and tube wall thermal inertia on predicted dynamic behavior is investigated.

EGR 밸브 평가 장치 개발을 위한 EGR 장착 엔진 성능 및 배출 가스 특성 연구 (A Study on Exhaust Gas Characteristics and Engine Performance of EGR Valve Installed Engine for Development of EGR Valve Test System)

  • 나동하;고춘식;서형준;이창언
    • 드라이브 ㆍ 컨트롤
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    • 제9권4호
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    • pp.52-57
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    • 2012
  • In this study, in order to understand contents and ranges of design for the EGR Valve test system for improving quality and performance of EGR Valve, engine performance and exhaust gas characteristic of 3L-class diesel engine was analyzed. Experimental operation of engine performance test was performed with 50% engine load and 20% and 100% opening ratio of EGR Valve. From test of performance and exhaust gas characteristic of engine, torque output of engine and temperature and pressure of inlet and outlet of EGR Valve were measured. As a result, for design of EGR Valve test system, input fluid flow of EGR Valve must be set the same amount with exhaust gas flow that was below of engine speed of 2,500 rpm, and temperature of inlet of EGR Valve must be set under about $510^{\circ}C$. And the difference of temperature between inlet and outlet of EGR Valve must be over than about $200^{\circ}C$. Exhaust gas of inlet and outlet of EGR Valve were under 1 bar that was not considerable, and the difference of pressure between inlet and outlet of EGR Valve were under 1 bar that could not effect on mechanical operation of EGR Valve.

PIV를 이용한 Uni-flow 소기방식 프리피스톤 수소기관의 실린더내 유동가시화 (Flow visualization used PIV of hydrogen fueled free piston engine with uni-flow scavenging)

  • 조형욱;윤재성;이종태;임희수
    • 한국수소및신에너지학회논문집
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    • 제19권3호
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    • pp.182-188
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    • 2008
  • In order to improve scavenging performance of free piston hydrogen fueled engine, this study estimate compatibility of uni-flow scavenging. The scavenging flow characteristics in the cylinder is investigated by flow visualization and PIV method. Consequently it has been found that the scavenging performance decreased with abnormal expansion of piston and delay of the exhaust valve opening timing. And the scavenging performance of exhaust valve located center in cylinder head is better than that of exhaust valve located side in cylinder head.

Bubble formation in globe valve and flow characteristics of partially filled pipe water flow

  • Nguyen, Quang Khai;Jung, Kwang Hyo;Lee, Gang Nam;Park, Hyun Jung;To, Peter;Suh, Sung Bu;Lee, Jaeyong
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제13권1호
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    • pp.554-565
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    • 2021
  • Air bubble entrainment is a phenomenon that can significantly reduce the efficiency of liquid motion in piping systems. In the present study, the bubble formation mechanism in a globe valve with 90% water fraction flow is explained by visualization study and pressure oscillation analysis. The shadowgraph imaging technique is applied to illustrate the unsteady flow inside the transparent valve. This helps to study the effect of bubbles induced by the globe valve on pressure distribution and valve flow coefficient. International Society of Automation (ISA) recommends locations for measuring pressure drop of the valve to determine its flow coefficient. This paper presents the comparison of the pressures at different locations along with the upstream and the downstream of the valve with the values at recommended positions by the ISA standard. The results show that in partially filled pipe flow, the discrepancies in pressure between different measurement locations in the valve downstream are significant at valve openings less than 30%. The aerated flow induces the oscillation in pressure and flow rate, which leads to the fluctuation in the flow coefficient of the valve. The flow coefficients have a linear relationship with the Reynolds number. For the same increase of Reynolds number, the flow coefficients grow faster with larger valve openings and level off at the opening of 50%.

풋 밸브가 적용된 지열 천공 DTH 해머의 성능 특성에 대한 실험적 연구 (Experimental Study on the Performance Characteristics of Geothermal DTH Hammer with Foot Valve)

  • 조민재;심정보;김영원
    • 한국지열·수열에너지학회논문집
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    • 제17권1호
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    • pp.14-22
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    • 2021
  • Drilling equipment is an essential part used in various fields such as construction, mining, etc., and it has drawn increasing attention in recent years. The drilling method is generally divided into three types. There are a top hammer method that strikes on the ground, a DTH (Down-The-Hole) method that directly strikes a bit in an underground area, and a rotary method that drills by using rotational force. Among them, the DTH method is most commonly used because it enables efficient drilling compared to other drilling methods. In the conventional DTH hammer, the valve between the piston and the bit is opened and closed using a face to face method. In order to improve the power of the DTH hammer, a DTH hammer with foot valve which is capable of instantaneous opening and closing is used in the drilling field. In this study, we designed a lab-scale DTH hammer with the foot valve, and manufactured an evaluation device for the experiment of the DTH hammer. In addition, we analyzed the performance of the DTH hammer adopted with foot valve according to the pressure range of 3-10 bar. As a result, the internal pressure distribution in the DTH hammer was experimentally analyzed, and then, the movement of the piston according to the pressure was predicted. We believe that this study provides the useful results to explain the performance characteristics of the DTH hammer with the foot valve.

EGR 밸브 용 모터 특성 분석 (The Characteristic Analysis of EGR Valve Motor)

  • 허준호;이선봉
    • 한국산학기술학회논문지
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    • 제17권2호
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    • pp.137-146
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    • 2016
  • EGR율이 증가할수록 $NO_X$ 저감에는 효과적이나, 과도한 EGR율은 오히려 불완전 연소의 주원인이 된다. 엄격한 배기규제를 만족하기 위해서는 엔진의 운행 조건에 최적화된 정밀한 EGR 밸브의 위치 제어가 뒷받침 되어야 한다. 따라서 본 연구에서는 EGR 밸브 용 모터 특성 분석을 위해 수학적 모델링과 제어 이론에 대해 연구하고, 마이크로칩 개발 툴을 이용하여 EGR 밸브용 모터의 위치를 제어하기 위한 단계로서 PWM(Pulse Width Modulation)의 듀티(duty)비의 입력 값에 따른 밸브 위치를 측정하여 개폐 구간 별 EGR 밸브 모터 특성을 분석하였다.

밸브 타이밍 지각과 과급에 의한 흡기관 분사식 수소기관의 고성능 실현 (The Realization of High Performance in a Hydrogen-Fueled Engine with External Mixture by Retarding Valve Timing and Super Charging)

  • 이광주;허상훈;이종태
    • 한국수소및신에너지학회논문집
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    • 제20권6호
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    • pp.464-470
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    • 2009
  • In order to analysis the possibility of high expansion and performance without backfire in a hydrogenfueled engine using external mixture injection, combustion characteristics and performance enhancement were analyzed in terms of retarding valve timing and increasing the boosting pressure. As the results, it was found that thermal efficiency increased by retarding intake valve timing with the same level of supplied energy is over 6.6% by the effect of high expansion including effect of combustion enhancement due to supercharging. It was also shown that the achievement of high power (equal to that of a gasoline engine), low brake specific fuel consumption and low emission (NOx of less than 16 ppm) without backfire in a hydrogen-fueled engine is possible around a boosting pressure of 1.5 bar, intake valve opening time of TDC and $\Phi$=0.35 in fuel-air equivalence ratio.

스로틀 개폐에 따른 가솔린 엔진의 비정상상태 유량변화 특성 (Characteristics of the Air Flow Variation by Throttle Step Change in a Gasoline Engine)

  • 박경석;고상근;노승탁;이종화
    • 한국자동차공학회논문집
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    • 제4권3호
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    • pp.92-101
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    • 1996
  • In a gasoline engine, the characteristics of air flow is very important not only for the design of the intake system geometry bout also for the accurate measurement of the induction air mass. In this study, an air flow rate measurement of the induction air mass. In this study, an air flow rate measurement was conducted by using the hot wire flow meter at the upstream of the intake port and the throttle. At the upstream of the throttle, the overshoot phenomena of the air flow rate by fast throttle opening were analyzed with choked flow. At the upstream of the intake port, the cylinder variation of the air flow rate and the difference between fast throttle opening and closing were showed during the unsteady state by the throttle step change. The results of this study can be used for the design of the throttle valve geometry and cylinder by cylinder control.

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압축공기 방식 수중발사 시스템의 동특성 시뮬레이션 (Simulations of Dynamic Characteristics of the Underwater Discharge System with Compressed Air)

  • 박인기
    • 한국군사과학기술학회지
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    • 제7권2호
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    • pp.41-47
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    • 2004
  • In this paper, simulations of the underwater discharge system with compressed air are performed to predict dynamic characteristics of the system and to find optimal opening trajectories of the expulsion valve. Major components of the system are defined and their governing equations are derived to make up the mathematical model. The compressed air discharge method is affected largely by the discharge depth, and therefore the opening trajectories according to the discharge depth should be found to satisfy the demands of discharge performances. Simulation results are compared with experimental data to confirm the validity of the system model.