• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.50-59
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• 2003

It was known that high pressure injection is an effective method to enhance thermal efficiency and decrease exhaust emissions in diesel engines. If injection pressure becomes ultra high, it is predicted that there may be a suitable injection pressure which the enhancement rate of spray characteristics is moderate. Also, there may be a limit injection pressure which spray characteristics is reversed and get worse. But these are unknown. To investigate a suitable injection pressure and a limit injection pressure, ultra high pressure injection equipment(UHPIE), which can realize the injection pressure of 3,200bar, was developed. UHPIE is a basic apparatus of single shot injection, and ultra high pressure was achieved by second stage rapid compression in short time. From the evaluation of UHPIE, a injection curve like a conventional diesel engine(jerk type) was realized. Also, it was proved that repetition of experiment was excellent. Therefore it was found that there was no problem to perform the study on the ultra high pressure injection with UHPIE. Consequently, the foundation of the study on ultra high pressure injection could be established.

• Journal of ILASS-Korea
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• v.7 no.4
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• pp.16-22
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• 2002

The characteristics of free spray with ultra injection pressure was analyzed to clear the limit pressure of diesel engine. To obtain final goal, ultra high pressure injection equipment was developed, spray patterns were visualized under various ultra injection pressures. Spray penetration and spray width, volume and entrained air mass were increased with the increase of injection pressure. Sauter mean diameter and injection durstion wert decreased. But over 3,000bar of ultra injection pressure region the rates of increase show almost similar and finally the reversed tendencies at 4,140bar.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.6
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• pp.7-12
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• 2005

In order to analyze the microscopic spray characteristics of free spray in ultra high pressure region, the droplets size and velocity of free spray injected under atmosphere condition were measured by PDPA. As injection pressure became ultra high pressure, the droplets size was decreased continuously due to the increase of mutual reaction between droplets and air. But the decreasing rate became moderate. The velocity was increased until 250 MPa, and then decreased over that of injection pressure. It was seemed that the droplet size was similar in range of $280\~350\;MPa$, but increased in 414 MPa, even though injection pressure was increased. The microscopic spray characteristics of free spray got worse in 414 MPa.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.131-137
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• 2005

Ultra high pressure injection equipment was developed to estimate and analyze the spray characteristics in ultra high pressure injection. Spray patterns were visualized by schlieren method and analyzed in ultra high pressure. Spray tip penetration, spray thickness, spray volume, and entrained air mass increased with the increase of the injection pressure. But over 2,800 bars of the injection pressure region, it was shown that the rate of improvement was not increased remarkably ,and the spray characteristics such as spray penetration, volume, and entrained air mass were reversed and got worse at 4,140 bars.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.442-447
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• 2003

The characteristics of instantaneous wall-surface temperature of impinging plate in case of ultra high pressure injection have been measured and analyzed by using thin film instantaneous temperature probe and ultra high pressure injection equipment. The decreasing rate of temperature was greater in case of higher temperature of impinging plate. Temperature drop was largest at center of piston and it was slight for others. Instantaneous temperature decreases rapidly with increasing injection pressure. But above 2,500bar of injection pressure, the decreasing rates are slightly affected by increasing injection pressure.

• Journal of ILASS-Korea
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• v.8 no.1
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• pp.29-36
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• 2003

Spray characteristics on diesel- water emulsion are analyzed in high pressure injection for several variables such as water content, injection pressure. Spray Patterns were visualized under various water content and injection pressures. Spray tip penetration was increased and spray angle decreased in accordance with increasing of water content. But these characteristics were enhanced with increase of injection pressure to high pressure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.3 s.234
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• pp.402-408
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• 2005

The instantaneous temperature behaviors on impinging plate in case of ultra high pressure have been measured and analyzed by using the instantaneous temperature probe and ultra high pressure injection equipment. The temperature drop was largest at P1 which is center of impinging spray and decreased with propagation of spray to the radius direction. The temperature drop was bigger in case of higher temperature of impinging plate. The temperature drop decreased with increase of injection pressure. But decreasing rate of temperature drop was slight over 2,500 bars. Therefore, it was predicted that the fuel evaporation versus the increase of injection pressure was maximum at around 2,500 bars.