• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.80-87
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• 2010

The purpose of this paper is to analyze the effects of ethanol blending ratio and fuel temperature in diesel-ethanol blended fuel on the spray-atomization characteristics in a high pressure common-rail injection system. In this work, a diesel fuel and three blended fuels were used as test fuels. Blended fuels were made by blending ethanol with a purity 99.9% to diesel fuel, from 0% to 30%. In order to keep diesel-ethanol blending stability, 5% of biodiesel fuel as volumetric ratio was added into test fuels. The fuel temperature was controled in steps with 40K, from 290K to 370K. Macroscopic spray characteristics were investigated by analyzing the spray tip penetration and spray cone angle through spray images obtained from visualization system. In addition, in order to study microscopic spray characteristics of ethanol blended fuels, the droplet diameter, was analyzed using the droplet measuring system. It is revealed that the spray tip penetration is similar regardless of ethanol blending ratio. As ethanol blending ratio is increased, the spray cone angle becomes wider. It is shown that the spray cone angle is affected by low viscosity and density of ethanol. As the fuel temperature increases, the spray tip penetration and spray cone angle become shorter and narrower respectively. The SMD of ethanol blending fuels is smaller than that of diesel fuel because of low viscosity and surface tension of ethanol.

• Journal of ILASS-Korea
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• v.16 no.1
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• pp.15-26
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• 2011

In this article, spray characteristics in CI engines fuelled with vegetable oils and its derivatives will be reviewed. Of edible vegetable oils, soybean oil and rapeseed oil were mainly investigated. Of inedible vegetable oils, jatropha oil and used frying oil were main concern on the research on the spray characteristics in CI engine. Spray angle and spray penetration were mainly examined among the macroscopic spray characteristics and Sauter mean diameter was only investigated among the microscopic spray characteristics. There exist six different definitions of spray angle which should be examined. Neat vegetable oil and biodiesel fuels show smaller spray angle than diesel fuel. Biodiesel fuel and vegetable oils and its blend have a longer spray penetration than diesel fuel. However, biodiesel blends with diesel shows the similar spray penetration with diesel fuel. SMDs in the biodiesel spray, vegetable oils and its blends spray are higher than that in the diesel spray.

• Journal of ILASS-Korea
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• v.2 no.2
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• pp.43-50
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• 1997

The purpose of this investigation is to carry out, the influence factor on the fuel spray characteristics for improve the engine combustion performance and exhaust omission in direct injection type diesel engine. The fuel properties, fuel spray structure and the shape or the piston surface of diesel engine play an important role of engine combustion process and exhaust emission. In order to obtain the effect of using auxiliary chamber and emulsified fuel on the fuel spray characteristics the experiment un conduct with single cylinder direct injection type diesel engine to examine the engine performance and gas emission. The results of this investigation showed that the increase auxiliary chamber volume and emulsified fuel give an effect on the fuel spray characteristics by reduced the concentration of nitric oxide emission in the combustion chamber. Also it can improve the combustion characteristics such as cylinder pressure, rate of pressure rise and rate of heat release.

• Journal of ILASS-Korea
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• v.6 no.3
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• pp.23-31
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• 2001

An experimental study was carried out to understand the spray characteristics of three kinds(kerosene, heating oil & diesel) of hydrocarbon-fuels. Fuel temperature and injection pressure were main variables in the experiment. Fuel Temperature was changed to obtain various levels of fuel viscosity. Spray angle and spray length were measured by using LVS(Laser Vapor Screen) photographs. 1D PDPA system was used to measure droplet size & droplet velocity. In room temperature, spray characteristics of three kinds of fuels were good, especially in case the fuel injection pressure was more than $6Kgf/cm^2$ It was also found that spray characteristics were poor in case fuel kinematic viscosity was more than 5cSt.

• Journal of ILASS-Korea
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• v.3 no.2
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• pp.24-33
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• 1998

The characteristics of liquefied butane spray are expected to be different from conventional diesel fuel spray, because a kind of flash boiling spray is expected when the back pressure is below the saturation vapor pressure of the butane(0.23MPa at $25^{\circ}C$). An accumulator type pintle injector and its fuel delivery system has been simulated in ruder to give injection pressure, needle lift and rate of fuel injected. The governing equation were solved by finite difference metho. The injection duration was controlled by solenoid valve. Spray behaviors such as a transient spray tip penetration, spray angle and SMD were calculated based on the empirical correlations in case that the back pressure is both above the vapor pressure of the butane and below that of butane. When the back preassure is below the vapor pressure of the fuel, conventional correlation is modified to represent the effect of flash boiling.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.128-136
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• 1997

Spray characteristics of a fuel injector have an important effect upon engine power and emission. Thus this study was investigated the spray characteristics of the intermittent injection using a gasoline fuel injector. Image processing system and PDA system were utilized for visualization of a spray behavior and measurements of a droplet size and velocity, respectively. Fuel injection duration was fixed with 3ms and injection pressure was varied such as 250kPa, 300kPa, 350kPa. for a high fuel injection pressure, spray tip arrival time was fluctuated at a vigorously disintegrated cross section. Axial velocity was linear correlated with fuel droplet size in the time interval of an injected main spray at spray downstream.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.194-201
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• 2000

This paper is intended to analyze the macroscopic behavior and transient atomization characteristics of the high-pressure gasoline injector in direct-injection gasoline engine. The global spray behavior of fuel injector was visualized by shadowgraph technique. Time-resolved droplet axial and radial velocity components and droplet diameter were measured at many probe positions in both axial and radial directions by a two-component phase Doppler particle analyzer (PDPA). In order to obtain the influence of fuel injection pressure, the macroscopic visualization and experiment of particle measurement on the fuel spray were investigated at 3,5 and 7 MPa of injection pressure under different surrounding pressure in the spray chamber. The results of this work show that the fuel injection pressure of gasoline injector in GDI engine has influence upon the mean droplet diameter, mean velocity of spray droplet, the spray tip penetration, and spray width under the elevated ambient pressure.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.5
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• pp.76-84
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• 1990

To study diesel fuel spray behavior, an experimental study was undertaken to investigate injection characteristics in vary ing back pressure and atomization mechanism in a non-evaporating diesel spray. Generally, injection characteristics is the curve of fuel flow plotted against time. The area under this curve is equal to the total quantity of fuel discharged for one injection. The method that measures rate of injection is long tube-type fuel rate indicator. Diesel spray injected into a quiescent gaseous environment under high pressure is observed by taking high speed camera by the focused shadow photographs. The results show that, at the start of injection, as the injected fuel rushes into the quiescent atmosphere the spray angle becomes large. Finally the spray stabilizes at a constant cone angle. Spray penetration length increases with the injection pressure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.187-194
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• 2001

Spray impingement and fuel film formation models were developed and incorporated into the computational fluid dynamics code. STAR-CD. The spray/wall interaction process was modeled by considering the change of behaviour with surface temperature conditions and the fuel film formation. We divided the behaviour of fuel droplets after impingement into rebound, spread and splash using the Weber number and the parameter K. The Spray impingement model accounts for mass conservation, energy conservation and heat transfer to the impinging droplets. The fuel film formation model was developed by integrating the continuity, Navier-Stokes and energy equations along the direction of fuel film thickness. Validation of the models was conducted using previous diesel spray experimental data and the present experimental results for the gasoline spray impingement. In all the cases, the prediction compared reasonably well with the experimental results. The spray impingement and fuel film formation models have been applied to the spray/wall impingement in high speed direct injection diesel engines.

• Journal of ILASS-Korea
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• v.11 no.2
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• pp.81-88
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• 2006

The spray characteristics of the rotating fuel injection system were investigated. The special test rig was devised to get the spatial and momentary droplet information. This experimental apparatus consists of a high-speed motor, a shaft, a rotating fuel nozzle and an acrylic case. Spray droplet size and velocity were measured by PDPA(Phase Doppler Particle Analyzer) and instantaneous velocity field was measured by 1'IV (Particle Image Velocimetry) system. At the same time, spray visualization was performed by using ND-YAG laser-based flash photography. From these two different laser diagnostic techniques, we could get spatial and instantaneous spray information fur rotating fuel injection system. The results presented in this paper indicate that spray characteristics such as droplet size, velocity and spray pattern were strongly influenced by rotational speed.