• Title/Summary/Keyword: internal combustion engine

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Start and Idle Combustion Characteristics of Hydrogen Engine for the HALE UAV (고고도 무인기용 수소 엔진의 시동성 및 공회전 연소 특성)

  • Kim, Yong-Rae;Choi, Young;Lee, Janghee
    • Journal of the Korean Institute of Gas
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    • v.19 no.6
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    • pp.22-27
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    • 2015
  • Hydrogen features highest energy density per mass and is expected to be desirable as a fuel of HALE(High altitude long endurance) UAV(Unmanned aerial vehicle). A reciprocating internal combustion engine is known to be a reliable and economic power source for this kind of UAV. Therefore, the combination of hydrogen and engine is worth of doing research. Test bench with 2.4L Spark-Ignited engine was prepared for the experiment in which start and combustion characteristics at idle condition were examined in this study. Stable hydrogen supply system and a universal ECU(Engine control unit) were also utilized for the test engine. Equivalence ratio and spark timings at idle operation were investigated and compared to the data of gasoline engine. The results will be a starting point for full-scale research of hydrogen engine for HALE UAV.

A Study on the Spray Characteristics of Flash Boiling Using Two Component Mixing Fuel (2성분 혼합연료를 이용한 감압비등 분무특성에 관한 연구)

  • Myong, Kwang-Jae;Yoon, Jun-Kyu
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.4
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    • pp.451-458
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    • 2009
  • This experimental study was conducted to investigate macroscopic characteristics of the flash boiling spray with tow component mixing fuel. Homogeneous Charge Compression Ignition (HCCI) is a newer combustion method for internal combustion engines to reduce nitrogen oxide and particulate matter simultaneously. But it is difficult to put this combustion method to practical use in an engine because of such problems as instability of combustion in low load operating conditions and knocking in high load operating conditions. In HCCI, combustion characteristics and exhaust emissions depend on conditions of air/fuel mixture and chemical reactions of fuel molecules. The fuel design approach is achieved by mixing two components which differ in properties such as density, viscosity, volatility, ignitability and so on. We plan to apply the fuel design approach to HCCI combustion generated in a real engine, and examine the possibility of mixture formation control using the flash boiling spray. Spray characteristics of two component fuel with a flash boiling phenomenon was investigated using Shlieren and Mie scattering photography. Test fuel was injected into a constant volume vessel at ambient conditions imitated injection timing BTDC of a real engine. As a result, it was found that a flash boiling phenomenon greatly changed spray structure, especially in the conditions of lower temperature and density. Therefore, availability of mixture formation control using flash boiling spray was suggested.

Development of Eco-Friendly Range Extension UTV Hybrid Vehicle System (주행거리 확장을 위한 하이브리드형친환경UTV 차량 시스템 개발)

  • Kim, Kee Joo;Won, Si Tae
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.12
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    • pp.1015-1020
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    • 2016
  • An advantage of electric vehicles is that they are environmentally sustainable because they do not emit exhaust gases, such as $CO_2$ or Nox. A disadvantage is the low power performance of the motor and battery source, necessitating a reduction in the weight of the vehicle to increase efficiency. Another disadvantage is that the rechargeable battery enables an electric vehicle to only run for a limited number of miles before requiring electric charging. To solve these problems, the hybrid vehicle has been developed by combining environmental sustainability with the high performance of a conventional internal combustion engine. In this study, an electric UTV (Utility Terrain Vehicle) was transformed into a hybrid vehicle system by outfitting the vehicle with a drive auxiliary power system including a 125 cc internal combustion engine. This modification enabled us to extend the range of the hybrid UTV from 50km to 100km per one electric charging.

Variation of Inter-Ring Gas Pressure in Internal Combustion Engine (내연기관 피스톤 링들 사이 가스압력 변동)

  • Yun, J.E.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.6
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    • pp.238-249
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    • 1995
  • The gas pressure acting on the rings in internal combustion engine influences the friction and wear characteristics. Inter-ring pressure variation during engine operation results from cylinder gas flow through a piston-ring pack. The flow passages consist of ring end gaps and clearances between the ring and the piston groove. The gas flow in the clearance between the ring and the groove is directly affected by the axial motion of the ring in the groove. In this paper the asperity contact force is newly considered in the prediction of the clearence between the ring and the groove surface. This term must be taken into account physically in case that the clearance get narrow rather than asperity height between the ring and the groove surface. Finally, comparisons of calculated inter-ring gas pressures based on the analytical method are made with the measured ones. The agereement was found to be good below midium engine speed, 3000rpm. In order to obtain accurate analytical results to the extend of high rpm range, it is recommended to include oil ring motion as well as top and second ring in analytical model.

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NUMERICAL ANALYSIS ON INTERNAL FLOW OF OIL JET COOLING THE PISTON (피스톤 냉각용 Oil jet 유동해석)

  • Kwon J.H.;Jung H.Y.;Lee J.H.;Choi Y.H.;Lee Y.W.
    • 한국전산유체공학회:학술대회논문집
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    • 2005.10a
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    • pp.219-222
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    • 2005
  • Recently, the interest of the engine capacity and environment of the atmosphere is increasing, so the researches for the engine capacity have been conducted for a long time. But the internal environment of an automotive engine is very severe. A piston is exposed to combustion gas of over $2000^{\circ}C$ and strong friction is occurred by high speed motion in the cylinder. The fraction between piston and wall of the cylinder causes the increase of temperature in the engine. The temperature of the engine has an effect on the engine capacity. If the temperature is high, the capacity of the engine is low. So we have to maintain the optimum temperature. To maintain the optimum temperature, the enough flow rate of the engine oil is needed. The oil jet is used to control the flow rate of the engine oil and supply the engine oil to the piston and cylinder. The purpose of this study is to check the mass flow rate of the engine oil and the characteristics of internal flow of the oil jet. Flow pattern of the engine oil is very important because it concludes the loss in the oil jet. This study is the previous research about the oil jet and we will consider the movement of the ball check valve to get more accuracy result.

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A Study on the In-Cylinder Injection Type Hydrogen Fueled S.I. Engine (연소실내 분사식 수소연료기관의 특성에 관한 연구)

  • 조우흠;이형승;김응서
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.7
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    • pp.1702-1708
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    • 1995
  • Owing to the serious problem of hydrocarbon fuel such as environmental pollution, the development of alternative fuel is very urgent. To adopt hydrogen to the internal combustion engine, a solenoid-drive type in-cylinder injection system was constructed. The injection system was installed to the single cylinder research engine, and the engine performance and the emission of citric oxide were tested upon the fuel-air equivalence ratio and the spark timing. In the case of in-cylinder injection system, hydrogen is injected after the intake valve is close, so it is possible to operate the engine without the back fire and the fall of its volumetric efficiency. In the region of the fuel-air equivalence ratio below 0.5, hydrogen and air aren't well mixed and the thermal efficiency is lowered, so the nozzle should be designed to inject hydrogen uniformly into the combustion chamber. In the region of the fuel-air equivalence ratio above 0.7,the fuel-air mixture burns very fast and the amount of citric oxide emission increases rapidly, so the spark timing should be retarded as compared with MBT.