• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.44-51
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• 2005

According to the increasing concern on the global environment, the $CO_2$ regulation has been discussed including automobile emission regulation. In order to cope with this rapid changing circumstances, the development of an ultra low emission and super fuel economy automobile is essential. Direct injection LPG engine is the one of the possible future engine to maximize the engine efficiency. This experimental study for the development of direct injection LPG engine technology is promoted with two parts; spray characteristics of high pressure swirl injector, and performance characteristics of direct injection LPG engine. Engine characteristics according to the fuel was analyzed in order to establish stratified combustion technology for LPG engine by using the DISI engine. In the engine experiment, control system was manufactured for gasoline and LPG fuel. The engine was modified 2,000 cc GDI engine (fuel supply device, fuel injection device). Through this experiment, engine operating condition, engine speed and spark timing (MBT), fuel injection position, and fuel rate were investigated.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.19-27
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• 2005

The spray characteristics of DISI injector has a great role in engine efficiency and emission. Thus, many researchers have been studied to investigate the spray characteristics of hollow cone type and slit type injector which are used in DISI engine. In this study, we tried to provide spray parameters which effect on the spray characteristics such as injection pressure, ambient pressure and ambient temperature. In addition, we calculated $t_b\;and\;t_c$ to investigate the break up mechanism of test injectors and also obtained $C_v$ to evaluate the spray characteristics. From this study, As the ambient pressure increases in case of slit injector, $C_v$ decreases.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.1-8
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• 2005

The spray prepared for direct fuel injection into cylinder is of great importance in a DISI(Direct Injection Spark Ignition) engine. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of in-cylinder flow conditions in the DISI engine. The Mie-scattering images presented the macroscopic view of the liquid spray fields interacting with cross-flow Particle sizes of fuel droplets were measured with phase Doppler anemometer(PDA) system. A faster cross-flow field made SMD larger and $D_10$ smaller. The atomization and evaporation processes with a DISI injector were observed and consequently utilized to construct the database on the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.68-76
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• 2012

Recently, the important issues of gasoline engine are to reduce the fuel consumption and emission. Thus, many researchers are studying the technology to solve these problems. One approach of these issues is to achieve homogeneous charge combustion and stratified change combustion with various injection strategy. In this study, the combustion characteristics of DISI engine accrding to injection strategy were examined. The effect of injection timing on lean limit A/F were investigated using dual DISI single cylinder. The results show that the engine operation region of dual DISI type engine is larger than that of PFI and DISI type engine cases. Especially, late injection is very effective to extend the operation region more than any other injection timings. In addition, the results show that when the DISI injection ratio is increase, leam limit A/F is improved. It means that the dual injection system car meet with emission regulations and reduce the fuel consumption. Also, combustion pressure of dual injection system is much higher than PFI and DISI injection.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.9
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• pp.722-727
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• 2009

The effect of the intake flow on the spray structure of a high pressure 11-hole fuel injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing and in-cylinder charge motion were investigated using the 2-dimensional Mie scattering technique. It was confirmed that in the homogeneous charge mode, the in-cylinder swirl charge motion played a major role in the fuel spray distribution during the induction stroke rather than the tumble flow. But, in the stratified charge mode, the effect of the in-cylinder charge was not so large that the injected spray pattern was nearly maintained and the increase of in-cylinder pressure by the upward moving piston reduced the fuel spray penetration.

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.186-187
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• 2001

No Abstract.See Full-text

• Journal of Power System Engineering
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• v.15 no.1
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• pp.5-10
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• 2011

The spatial fuel vapor distribution of the homogeneous charge by a 6-hole injector was examined in a optically accessed single cylinder direct injection spark ignition(DISI) engine. The effects of in-cylinder charge motion, and fuel injection pressure, and coolant temperature were investigated using a planar LIF (Laser Induced Fluorescence) technique. It was confirmed that the in-cylinder tumble flow played a little more effective role in the spatial fuel vapor distribution than the swirl flow during the compression stroke at 10 mm and 2 mm planes under cylinder head gasket and the increased fuel injection pressure activated spatial distributions of the fuel vapor. In additions, richer mixtures were concentrated around the cylinder wall by the increase of the coolant temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.11
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• pp.878-883
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• 2008

The spray characteristics of a high pressure 6-hole injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing, in-cylinder charge motion, fuel injection pressure and coolant temperature were investigated using the 2-dimensional Mie scattering technique. It was confirmed that the in-cylinder charge motion played a major role in the fuel spray distribution during the induction stroke while the propagation of fuel spray was restrained during the compression stroke by the increasing pressure and the upward moving piston. In additions, it was confirmed that the liquid fuel droplets existing at the sprays edges were vaporized by the increase of the coolant temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.30-39
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• 2001

The direct injection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced by the high pressure injector is of paramount importance in DISI(Direct Injection Spark Ignition) engines in that the primary atomization process must meet the requirement of quick and complete evaporation, mixing with air and combustion especially to prohibit the excessive HC emissions. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the DISI engine. The direct Mie scattered and shadowgraph images presented the macroscopic view of the liquid sprays and vapor fields. The velocity and particle size of fuel droplets were investigated by phase doppler anenometer(PDA) system. The processes of atomization and evaporation with a DISI injector were observed and consequently utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.65-72
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• 2011

In this study, the numbers, sizes of particles from a single cylinder direct injection spark-ignition (DISI) engine fuelled with gasoline and LPG are examined over a wide range of engine operating conditions. Tests are conducted with various engine loads (2~10bar of IMEP) and fuel injection pressures (60, 90, and 120 bar) at the engine speed of 1,500 rpm. Particles are sampled directly from the exhaust pipe using rotating disk thermodiluter. The size distributions are measured using a scanning mobility particle sizer (SMPS) and the particle number concentrations are measured using a condensation particle counter (CPC). The results show that maximum brake torque (MBT) timing for LPG fuel is less sensitive to engine load and its combustion stability is also better than that for gasoline fuel. The total particle number concentration for LPG was lower by a factor of 100 compared to the results of gasoline emission due to the good vaporization characteristic of LPG. Test result presents that LPG for direct injection spark ignition engine help the particle emission level to reduce.