• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.196-199
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• 2011

Subscale high-pressure injection system which use two-stage light gas gun composed with high-pressure tube, pump tube and launch tube can make supersonic liquid jet. The supersonic liquid jet enhances droplet atomization by shockwave in front of the jet. In this study, the experiments was executed to identify the atomization characteristics of the supersonic liquid jet using straight cone nozzle. SMD which presents the atomization characteristics was decreased from $151.2{\mu}m$ to $52.25{\mu}m$ by increasing of L/d.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.999-1004
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• 2010

Recently, many technologies have been developed in order to satisfy stringent emission regulations. However, in the case of diesel engines, the stringent emission regulations with respect to NOx and PM have not yet been satisfied. A dramatic reduction in the NOx and PM emissions could be achieved by using after-treatment systems such as lean NOx trap (LNT) and urea-SCR systems. However, the high temperature in the exhaust pipe affects the spray behavior of the secondary injector, which is used for supplying the Urea-SCR. Because of this high temperature, it is difficult to achieve uniform distribution of the reducing agent in the manifold. In this paper, the characteristics of a urea-SCR injector used for injecting in the exhaust pipe are presented. The purpose of this study was to investigate the spray characteristics of the injector, such as the spray angle, injection quantity, and SMD. In addition, laser diagnostics and high-speed-camera images were used to analyze the injector spray characteristics and to present a distribution of reduction in the transparent manifold.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.491-498
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• 2010

Humidification of PEM fuel cells is necessary for enhancing their performance and lifetime. In this study, a humidification system was designed and tested; the system includes an air-supply tube (inner diameter: 75 mm) through which a nozzle can be directly inserted and a cyclonic separator for the removal of water droplets. Three types of nozzles were employed to study the influence of injection pressure, air flow rate, and spray direction on the humidification performance. To evaluate the humidification performance, the concept of humidification efficiency was defined. In the absence of an external heat source, latent heat for evaporation will be supplied by the own enthalpies of water and air. Thus, the amount of water sprayed from the nozzle is the most critical factor affecting the humidification efficiency. Water droplets were efficiently removed by a cyclonic separator, but re-entrainment occurred at high air flow rates. The absolute humidity and humidification efficiency were $21.29\;kJ/kg_{da}$ and 86.57%, respectively, under the following conditions: nozzle type PJ24; spray direction angle $90^{\circ}$; injection pressure 1200 kPa; air flow rate 6000 Nlpm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.991-998
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• 2013

The fuel injection pipe of a common rail system used in a clean diesel vehicle plays a role in supplying fuel from a rail to the injector of each cylinder connecting the engine under a repeated internal pressure. The fuel injection pressure is increased to over 200 MPa for satisfying EU emission standards and improving fuel efficiency, and a heading process and an autofrettage process are required for preventing folding defects and improving fatigue life. In this study, the flow stress and SN data of the material of the pipe are obtained through a tensile test and a fatigue test. The heading process for checking the folding defects of pipe ends is performed by using FEA. Furthermore, the optimal design of the autofrettage process for improving fatigue life considering not only the compressive residual stresses of the inner surface but also the tensile residual stresses of the outer surfaces of the pipe under the repeated internal pressure is performed by using FEA. To verify the process design, fatigue analysis for the autofrettaged pipe is performed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.2
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• pp.192-203
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• 1990

여러 가지 다른 형태의 노즐을 공기 선회식 버너와 공기의 선회가 없는 버너(CB-125 Burner)에 장치하여 공기 분사식으로 오일을 분사하여 연소로에서 연소시켰다. 연소로는 길이 3m에 약 1m 상(3) 의 연소공간을 가졌으며 상부에는 열전대를 장치하고 하부에는 물이 흐르는 관을 설치하여 열효율을 계산할 수 있게 설계하였다. 연소로 연돌부에는 CO 하(2), CO, O 하(2) 가스 분석기를 사용하여 과잉공기량과 고온계로 배기가스 온도를 측정하도록 하였다. 모든 측정치는 연소곡선과 효율곡선에 의하여 얻어진 상수를 이용하여 계산한 연소로 성능방정식에 의하여 평가하였다. 실험치에 의해 계산한 벽면 열손실량과 열전달 공식에 의해 산출한 열손실량을 비교 분석하여 측정치의 정확도를 추정하고 과잉공기의 효과도 검토하였다. 그 결과 본 연구에서 사용된 두 종류의 버너와 여러 형태의 노즐이 오일 연소시 열효율 면에서 큰 차이를 보이지 않고 있음을 알았다.

• 기계와재료
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• v.24 no.2
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• pp.62-71
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• 2012

세계적으로 NOx 저감 및 규제치의 강화로 인해 디젤기관에서 발생되는 NOx 제거에 대한 연구가 활발히 진행 중이며, 암모니아 환원제와 배출가스의 NOx를 혼합하여 촉매 존재하에서 NOx를 제거하는 시스템이 개발되고 있다. 대부분 암모니아를 보관성이 용의한 요소(Urea) 수용액으로 대체하여 배기관 내에 직접 요소수를 분사하며 요소 수용액이 고온의 배기가스에 의해 증발되어 암모니아를 환원시키며, 촉매를 통하여 탈질을 하는 Urea-SCR 시스템을 채택하고 있다. 따라서 촉매전단에서 요소수가 완전히 증발되고, 또한 촉매 입구에서 요소수의 증발로 인해 환원된 암모니아의 분포도 균일해야 함으로 Urea-SCR 시스템이 배기가스 유동 및 온도에 최적화된 분무특성을 가지는 분사제어 시스템을 제시하고자 한다.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.6
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• pp.628-636
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• 2005

In this paper. the effects of a WI(Water Injection) in the intake pipe for a 4-cylinder Dl(Direct Injection) diesel engine are investigated experimentally, The WI system was controlled by the duty cycle from the intake manifold's temperature and MAF(Manifold Air Flow) First. effect of EGR on NOx reduction was investigated. Then WI system was applied to reduce NOx As the results. we can make the NOx map and visualize the NOx results by variation of engine speed and engine load It was known that effect of WI system on NOx reduction without the EGR was better than the with EGR base engine except of low load and speed condition.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2186-2191
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• 2003

This study is to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in diesel engine. The effects of water induction through the air intake port were considered in IDI diesel engine in this study. The formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water play a role as a heat sink during evaporating in the combustion chamber, but the smoke was slightly increased with increased water amount. Also, NOx significantly decreased with increase in water amount. A simultaneous reduction in smoke and NOx emissions can be obtained when water is injected into the combustion chamber by retarding the fuel injection timing more than without water injection.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.4
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• pp.298-304
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• 1984

본 연구에서는 저자들이 디이젤기관 제조업체에서 디이젤 기관의 성능개선을 효율적으로 수행하기 위하여 기업체 연구소에서 쉽게 적용할 수 있는 시뮬레이션 프로 그램을 개발하는 과정에서 수행된 것이며, 아울러 각 기관 회전수에서의 연료분사 관 내에서의 압력변화와 노즐 니이들 밸브 양정을 측정함으로써 수학적 시뮬레이션 결과 와 실제결과를 비교할 수 있게 하였다. 그 결과, 개발된 시뮬레이션 프로그램은 실 제 연료분사 과정을 충분히 잘 예측할 수 있었으며, 향후 이 프로그램을 이용하여 연 료분사계의 조정에 의한 디이젤기관 성능개선을 효율적으로 수행할 수 있을 것으로 기 대한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.83-88
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• 2007

The spray characteristics and liquid column penetration of steady and pulsed injection measurements have been experimentally studied using high speed camera in liquid jets injected into subsonic crossflow. The objectives of this research are to comparison the spray characteristics of steady injection with pulsed injection. Moreover. the effects of frequency are also studied. As the result, This research has been showed that pulsed injection has different penetration compared with steady injection.