• 한국분무공학회지
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• 제6권2호
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• pp.9-15
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• 2001

The internal flow characteristics of a gasoline direct injector have been studied to improve fuel economy and reduce exhaust emissions. Computational Fluid Dynamics (CFD) is used to examine the internal flow of the GDI with the purpose of designing the optimum geometry of the injector. This study tests orifice length, cone angle, swirl angle, orifice diameter and needle lift. The results show that optimum sizes of the orifice length, cone angle, swirl angle, orifice diameter and needle lift are 0.8mm, $140^{\circ},\;120^{\circ},\;80mm\;and\;70{\mu}m$, respectively. The size of the lift does not affect the formation of the air core signficantly near the tip of the needle compared to the ball-type needle. The vena contracta phenomenon near the orifice inlet can be released by smoothing the edge.

• 한국수소및신에너지학회논문집
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• 제28권3호
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• pp.300-307
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• 2017

This study is to investigate particle size and velocity profile of gasoline port injector using Phase Doppler Particle Analyzer (PDPA). In this experiment, a GV 250 Delphi port injector used for motorcycles was used for liquid injection. The injector consists of four holes and has a static flow rate of 2.13 g/s. The fuel used in the injection was N-heptane, which is similar to gasoline, as an alternative fuel. The test fuel was injected at an atmospheric temperature of $20^{\circ}C$ and an open atmosphere of 1 atm. The injection time was 10 ms and the injection pressure was 3.5 bar in PDPA experiment. The experimental target position was fiexd at 30, 50 and 75 mm from the nozzle tip and data were collected for a total of 10,000 samples. The experimental results show that the length diameter (D10), the Sauter mean diameter ($D_{32}$), and the mean droplet velocity (MDV) are $45-54{\mu}m$, $99-115{\mu}m$ and 15-21 m/s, respectively.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2005-2010
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• 2011

최근 배기 규제가 자동차 엔진에 국한되지 않고 노외용 소형엔진 부분에서도 세계적으로 강화됨에 따라, 배기규제에 대응하기 위하여 기존 노외용 소형엔진의 기화기 방식에서 벗어나 전자연료 분무방식으로의 전환이 필요하게 되었다. 본 연구에서는 400cc 가솔린 엔진용 인젝터의 연료공급 특성을 실험적으로 분석하였으며, 이를 토대로 소형엔진에 적합한 인젝터를 선정하였다. 분무질량분포 측정장치를 통하여 3홀 및 6홀인젝터의 분무질량분포 특성을 분석하였다. 가시화 실험 장치를 통하여 각 인젝터의 분무각, 분무도달거리 및 분무폭을 분석하였다. 분무질량분포 실험 및 분무 가시화 실험을 통하여 분무특성이 우수하고 안정적인 분무를 형성하는 6홀 인젝터를 소형엔진용으로 선정하였다.

• 한국분무공학회지
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• 제3권1호
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• pp.34-42
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• 1998

The correlation between the droplets size and the velocity are investigated for an intermittent spray of the pintle type fuel injector employed in a port injection gasoline engine. The analysis such as the mean droplet size, SMD, and velocity under the fixed injection period and varied fuel pressures are conducted utilizing PDPA systems. As results, the experimental data obtained, show that the larger droplet sizes. the higher velocities during the spray tip arrival time, and that at Z=70mm, r=8mm, both droplet sizes and velocities are peak. At the upstream, flow of droplets are dominated by injection pressure, which are more effected inertia force of droplets at the downstream of Z=70mm.

• 한국자동차공학회논문집
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• 제3권1호
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• pp.118-130
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• 1995

Fuel spray in a gasoline engine is a significant factor for the decision of engine power, pollutant emission and the design of intake manifold system. Three kinds of fuel which has other physical properties are chosen in this study, and it is observed using an image processing method that the mechanism and structure of free fuel spray with a throttle type gasoline injector, and the detailed characteristics of droplet size and velocity distributions are obtained by macro and micro-scopic measuring method respectively. It is verified that the initial breakup behaviors are depended on We like the result of Reitz's study, and also observed that the spray of octane and solvent with Re of 210~330 and 270~330 respectively are better than ethanol which has relatively high density and viscosity.

• 한국분무공학회지
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• 제11권1호
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• pp.17-23
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• 2006

The influence of fuel spray characteristics on engine performance has been known as one of the major concerns to Improve fuel economy and to reduce exhaust emissions. In general, the UBHC(Unburned Hydrocarbon) emission could be reduced by decreasing the droplet size of the fuel sprays. In PFI (Port Fuel Injection) gasoline engines, the mixture of air and fuel would not be uniform under a certain condition, because the breakup and production of spray droplets are made in a short distance between the fuel injector and intake valve sheat. In this study, were investigated the transient spray characteristics and dynamic behavior of droplets from 2holes-2sprays and 4holes-2sprays type injectors used in PFI gasoline engine. Mean droplet size and optical concentration were measured by LDPA (Laser Diffraction Particle size Analyzer). The variation of droplet mean diameter and optical concentration were measured for understanding the behavior of unsteady spray.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.112-120
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• 2005

The injector, which is used in a 4-valve gasoline engine, is required to be maintained the dual stream because of the design of dual intake port. In addition, the spray characteristics of fuel injector have strong influence on engine performance, exhaust emission, fuel consumption, and especially the cold start condition for the port injection. So, commercial gasoline injectors off different type were inspected. Those are 2 hole,4 hole, air shroud 4 hole, and air shroud 4 hole injector with separator. The spray behavior of dual stream was researched by the visualization system and PDPA system was employed to measure the droplet size. Atomization is one of the most important characteristic, so droplet size distributions and SMD are investigated. And the spray characteristics of each injector are also analyzed such as the spray tip penetration, spray angle, and separation angle.

• 한국분무공학회지
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• 제19권1호
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• pp.1-8
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• 2014

Liquefied petroleum gas (LPG) is regarded as an alternative fuel for spark ignition engine due to similar or even higher octane number. In addition, LPG has better fuel characteristics including high vaporization characteristic and low carbon/hydrogen ratio leading to a reduction in carbon dioxide emission. Recently, development of LPG direct injection system started to improve performance of vehicles fuelled with LPG. However, spray characteristics of LPG were not well understood, which is should be known to develop injector for LPG direct injection engines. In this study, effects of operation condition including ambient pressure, temperature, and injection pressure on spray properties of n-butane were evaluated and compared to gasoline in a multi-hole injector. As general characteristics of both fuels, spray penetration becomes smaller with an increase of ambient pressure as well as a reduction in the injection pressure. However, it is found that evaporation of n-butane was faster compared to gasoline under all experimental condition. As a result, spray penetration of n-butane was shorter than that of gasoline. This result was due to higher vapor pressure and lower boiling point of n-butane. On the other hand, spray angle of both fuels do not vary much except under high ambient temperature conditions. Furthermore, spray shape of n-butane spray becomes completely different from that of gasoline at high ambient temperature conditions due to flash boiling of n-butane.

• 동력기계공학회지
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• 제13권3호
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• pp.5-10
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• 2009

This work deals with a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. The fuel is injected indirectly into electrically heated inlet air flow. In order to keep a homogeneous air-fuel mixing, the fuel injector is cooled by the water of a specially designed coolant passage. The engine emission characteristics were investigated under the wide range of operating conditions such as 32 to 63 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, and 150 to $180^{\circ}C$ in the inlet air temperature. The ultra lean-burn can be achieved by the auto-ignition of gasoline fuel due to the heated inlet air in the compression ignition gasoline engine. It is confirmed that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxide can be significantly reduced by CAI combustion compared with the combustion of a conventional spark ignition engine.

• 한국자동차공학회논문집
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• 제5권2호
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• pp.42-49
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• 1997

This experimental study was performed to find fuel property variations of the ultrasonic energy adding gasoline and improve the spray characteristics of the multipoint injector for EFI engine. The cause and effect of the characteristic improvement of the ultrasonic energy adding fuel was found out by the chemical structure analysis (NMR, IR), distillation and viscosity test. The results are obtained that the chemical property of gasoline organizition was changed aromatics to paraffins and branch index as the physical characteristics of gasoline were improved by ultrasonic energy. There were higher distillation and lower viscosity in ultrasonic energy adding gasoline.