• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.25-31
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• 2004

Two-dimensional laser visualization methods have been used in the study of breakup and atomization processes of non-evaporating diesel sprays. A single-hole spray injected into a quiescent atmospheric environment was visualized by the LIF(Laser Induced Fluorescence) and scattering technique. The LIF technique could be implemented to take the images which are magnified enough to show the shape of liquid ligaments and small droplets. The spontaneous scattering and fluorescent images of sprays were also taken to investigate the atomization of droplets. In the tip and periphery of a spray. the scattering light is bright and the ratio of fluorescent/scattering intensity is lower. This characteristics indicate the very high number density of small droplets which are well atomized.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.22-28
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• 1999

The injected liquid does not break-up instantly after injection for diesel engine. There is some unbroken portion, which is the liquid core(The length of liquid core is called the break-up length) in the spray. If the liquid core is longer than the depth of the bowl in the small DI diesel engine, the liquid core impinges on the surface of the piston. Once the liquid core impinges on the surface, it cannot ignite or burn rapidly and thus prolongs burning time with a degradation in thermal efficiency. The break-up length of a diesel spray in a compressure vessel was measured by an electric resistance method, A voltage was applied between the nozzle and screen, bar, needle electrode inserted at various axial and radial positions into atomizing sprays. As a result, a current flows not only in the region of liquid core but also through the droplets of the spray. It is found that the break-up length measured with screen electrode is overestimated. The break-up length of the spray is found to be proportional to the square root of the density ratio of fuel and surrounding gas. The break-up length of the spray decreases as the injection pressure and the back pressure increase.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.9
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• pp.763-771
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• 2014

As a preliminary study on the spray behavior characteristics of emulsified fuel, the fuel properties (viscosity, surface tension, and density) and evaporation characteristics of a fuel droplet were investigated. The emulsified fuel was made by mixing diesel and $H_2O_2$. In addition, the macroscopic spray behavior characteristics such as the spray penetrations and spray angles of the emulsified and diesel fuels were compared. The stirring condition of the emulsified fuel was a 9:1 mixture of the diesel fuel and the surfactant span 80. The mixing ratios for the hydrogen peroxide were set at EF2, EF12, EF22, EF32, EF42, EF52, EF62, EF72, EF82, and EF92. The injection pressures were set at 400, 600, 800, and 1000 bar. We found that as the mixing ratio of the hydrogen peroxide was increased from EF2 to EF52, the viscosity of the emulsified fuel increased. However, afterward, the viscosity of the emulsified fuel gradually decreased and approached the viscosity value of the diesel fuel. Therefore, generally oil-in-water emulsions were used for the hydrogen peroxide mixing ratios up to 52 (EF52), and water-in-oil emulsions were used for the hydrogen peroxide mixing ratios above 52. Finally, the spray behavior characteristics (spray penetration and spray angle) of the emulsified fuel were found to be almost independent of the mixing ratio.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.745-752
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• 2012

Diesel engines are most suitable for biodiesel fuel because diesel fuel has a higher cetane number compared to gasoline and diesel engines have no spark ignition system; hence, engine conversion is easy and cost effective. For these reasons, in this study, the spray behavior characteristics of vegetable palm oil were analyzed by using a common-rail injection system of a commercial diesel engine, and the results were compared with those obtained for the diesel fuel. The injection pressures and blend ratios of palm oil and diesel fuel (BD3, BD5, BD20, BD30, BD50, and BD100) were the main parameters. The experiments were conducted for different injection pressures-500 bar, 1000 bar, 1500 bar, and 1600 bar-by setting the injection duration at $500{\mu}s$. We determined there is no significant difference in the macro characteristics of the spray behavior (spray penetration and spray angle) in response to any change in the blend ratio of palm oil and diesel fuel at a fixed injection pressure. In particular, all experiments showed a spray angle of approximately $15^{\circ}$.

• Journal of ILASS-Korea
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• v.1 no.2
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• pp.1-7
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• 1996

• Journal of ILASS-Korea
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• v.1 no.3
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• pp.6-19
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• 1996

• Journal of ILASS-Korea
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• v.1 no.3
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• pp.1-5
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• 1996

• Journal of ILASS-Korea
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• v.20 no.3
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• pp.187-194
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• 2015

In this study, three visualization methods, Schlieren, Shadowgraph, and Mie-scattering, were applied to compare diesel and gasoline spray structures. Fuels were injected into a high pressure/high temperature constant volume chamber under the same ambient pressure and temperature condition of low load in gasoline direct injection compression ignition (GDCI) engine. Two injection pressures (40 and 80 MPa), two ambient pressures (4.2 and 1.7 MPa), and two ambient temperatures (908 and 677 K) were use. The images from the different methods were overlapped to show liquid and vapor phases more clearly. It was found that the gasoline fuel is more appropriate to form a lean mixture.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.812-817
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• 2001

Impinging spray characteristics were investigated to find suitable injection pressure by using high pressure injection system. Spray radius and spray height were increased continuously until 2,500bar but the rate of enhancement was decreased suddenly over this injection pressure region. It is expected that the maximum suitable injection pressure of impinging spray exists at around 2,500bar.

• Journal of ILASS-Korea
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• v.25 no.1
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• pp.15-20
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• 2020

This study aims to investigate injection rate and microscopic spray characteristics of diesel fuel containing fine air bubble (FBD). fine bubble was generated by cavitation theory using bubble generator. Fuel spray was injected into constant volume chamber and visualized by high speed camera. The injection rate data was acquired with bosch tube method. Injection rate of finebubble diesel was very similar with that of diesel. It showed slightly faster injection start by 5 ㎲ attributed to the low viscosity characteristics. In microscopic spray visualization, fine bubble diesel spray showed unsymmetric spray shape compared with diesel spray. It also showed very vigorous spray atomization performance during initial spray development. Improved atomization was also attributed to the low viscosity and surface tension of finebubble diesel fuel.