• 한국분무공학회지
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• 제5권2호
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• pp.35-42
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• 2000

A number of atomization and droplet breakup models have been developed and used to predict the diesel spray characteristics. Of the many atomization and droplet breakup models based on the breakup mechanism due to aerodynamic liquid and gas interaction, four models classified as mathematical models, such as TAB, modified TAB, DDB, WB and one of the hybrid model based on WB and TAB models were selected for the assessment of prediction ability of diesel spray dynamics. The assessment of these models by using KIVA-II code was performed by comparing with the experimental data of spray tip penetration and sauter mean diameter(SMD) from the literature. It is found that the prediction of spray tip penetration and SMD by the hybrid model was only influenced by the initial parcel number. All the atomization and droplet breakup models considered here was strongly dependent on the grid resolution. Therefore it is important to check the grid resolution to get an acceptable results in selecting the models. At low injection pressure, modified TAB model could only give the good agreement with experimental data of spray tip penetration and both of modified TAB and DDB models were recommendable for the prediction of SMD. At high injection pressure, hybrid model could only give the good agreement with the experimental data of spray tip penetration and the prediction of all of the selected models did not match the experimental data. Spray tip penetration was increased with the increase the $B_1$ and the increase of $B_1$ did not affected the prediction of SMD.

• Journal of Advanced Marine Engineering and Technology
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• 제22권6호
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• pp.827-835
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• 1998

The effects of recirculated exhaust gas on the wear of cylinder liner piston and piston rings have been investigated by the experiment with a two-cylinder four cycle indirect injection diesel engine operating at 75% load and 1600 rpm speed For the purpose of comparison between the rates of two cylinders with and without EGR the recirculated exhaust gas is sucked into one of two cylinders after the soot among exhaust emissions is removed by an intntionally designed cylinder-type scrubber equipped with 6 water injectors(A water injector has 144 nozzles of 1.0 mm diame-ter) while only the fresh air into another cylinder. These experiments are carried out on the fuel injection at a fixed $15.3^{\circ}$ BTDC timing. It is found that firstly the mean wear amount of cylinder liner with EGR is more increased in the measurement positions of the second half than of the first half and the mean wear amount without EGR is almost uniform regardless of measurement posi-tions secondly the wear rates of the first and second piston ring(compression ring)thickness with EGR are more than twice but the wear rate of oil ring thickness without EGR is more increased than that with EGR and finally the wear rate of piston skirt with EGR is a little bit increased but the piston hed diameter is rather increased owing to soot adhesion and corrosion wear and espe-cially larger with EGR.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.4729-4735
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• 2014

적극적인 환경보호를 위해 그동안 상대적으로 소홀하였던 오프로드 엔진에 대한 배기가스 배출 규제가 강화되고 있다. 본 연구에서는 NOx와 PM 배출물 특성을 고려하여 오프로드 디젤 엔진의 강건 설계를 수행하였다. 이를 위하여 실험계획법에 따라 배출물 NOx와 PM의 측정 실험을 수행하고 다구찌 기법으로 망소 SN 비를 산출하고 분산 분석을 수행하였다. NOx와 PM 배출량에 영향을 미치는 제어 인잘로 인젝터 홀 수, 연료 분사 시기, EGR 율을 선택하였으며 각 제어 인자에 대하여 2 또는 3 수준을 고려하여 직교 배열표를 작성하였고, 이에 근거하여 실험을 수행하였다. 망소 SN 비를 산출하고 델타 통계량을 계산하였다. 저부하 운전 조건에서는 분사 시기가 NOx 배출량에 가장 큰 영향을 미치며, EGR 율이 PM 배출량에 가장 큰 영향을 미치는 결과를 얻었다. 제어 인자들에 대한 신뢰수준은 90% 이상이었다.

• 한국분무공학회지
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• 제25권3호
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• pp.111-118
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• 2020

This paper describes the effect of DME, biodiesel blended fuels on the macroscopic spray characteristics in a high pressure diesel injection system using Background Oriented Schlieren (BOS) method. The BOS method for visualization of impingement evaporation sprays to analyze macroscopic spray properties and evolutionary processes. In this work, the blending ratio of DME in the blended fuel are 0, 50, 100% by weight ratio. In order to investigate the macroscopic impinged spray characteristics under the various injection parameters and blending ratio. In this work, a mini-sac type single-hole nozzle injector with nozzle hole was length 0.7 mm and diameter of 0.3 mm was used. According to the result, the spray area of the collision wall increased as the DME mixing ratio increased, and the evolutionary pattern showed a stepwise increase due to the collision effect of the wall. Also, results of impinged spray area were increased according to increasing injection pressure.

• 한국연소학회지
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• 제15권4호
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• pp.53-57
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• 2010

The purpose of the present work is to investigate the effect of gasoline-premixing on a combustion and emissions characteristics in a compression ignition engine. For studying combustion characteristics, a combustion pressure and rate of heat release (ROHR) were measured using a single-cylinder DI compression ignition engine with a common-rail injection system and premixed fuel injection system. In addition, exhaust emissions characteristics were studied using emission analyzers and smoke meter. The experimental results showed that the case of gasoline-premixing had longer ignition delay and lower combustion pressure compared to the cases of diesel direct injection. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of ROHR.

• 한국분무공학회지
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• 제3권2호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.946-951
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• 2001

This experimental study is to investigate the intermittent spray characteristics of a pintle nozzle. High speed camera used in this expreiment with 9000fps. The factor, which controls the diesel spray, is the Injection pressure, ambient pressure and ambient temperature. In this paper, experiments were conducted free spray for the ambient pressure(3, 4, 5Mpa), nozzle Injection pressure(10, 14, 18MPa) and ambient temperature(293, 473K). With the higher opening pressure, the spray tip velocity and spray penetration increases while the spray angle decreases, On the other hand, With the higher ambient pressure, the spray angle increase while the spray tip penetration and spray tip velocity decrease. also, With the higher ambient temperature, the spray penetration decrease while the spray angle decrease.

• Journal of Advanced Marine Engineering and Technology
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• 제16권1호
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• pp.35-46
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• 1992

In this study, we calculated gas flow fields and distribution of fuel droplet and mass fraction using the CONCHAS-SPRAY code which modified to execute in IBM PC and changed three important factors, injection rate pattern (BASIC, I, II, III), different bowl shape and spray type. Especially vortices which be influenced by fuel-air mixing process, evaporation and flame propagation are generated more strongly in the bowl-piston type combustion chamber than in the flat-piston type. As the spray type changes, it is found that conical type produced large and strong vortices and fuel droplets are effictively diffused into the entire combustion chamber. As the injection rate pattern changes I, II, III based on BASIC type, we confirmed that End-of-Injection Effect strongly influence on droplets life time.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.1-7
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• 2001

Recently, several LPG engines for heavy-duty vehicles have been developed, which can replace some diesel engines that are one of a main source for air pollution in urban area. As a preliminary study on the liquid phase LPG injection (hereafter LPLI) system applicable to a heavy duty LPG engine, the engine output and combustion performance were investigated with various combustion chambers and fuel compositions using a single cylinder engine equipped. Experimental results revealed that ellipse, double ellipse and nebula type combustion chamber made a more advantage in breaking swirl flow into small turbulence scale than bathtub type. Especially, performance of nebula type showed most highest efficiency and engine output under lean mixture conditions. An investigation fur various LPG fuel compositions was also carried out, and revealed that the case with 40% propane and 60% butane shows the lowest efficiency at stoichiometry, however, as the mixture became leaner its efficiency increased and became even higher for 100% propane case.

• 오토저널
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• 제13권5호
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• pp.81-88
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• 1991

Combustion characteristic, concentration of NOx and exhaust smoke opacity was experimentally tested, according to fuel injection timing, mixing ratio of water and methanol for the driving condition of 2000 rpm of engine revolution and constant load(7.5kg/cm$^{2}$) using emulsified fuel of gas oil-water methanol. The result obtained was as following. Thermal efficiency indicated highly 0.4-2.7% for emulsified fuel then gas oil, and injection timing when maximum thermal efficiency, slicily risen then gas oil. For constant fuel injection timing ignition lag was increased, combustion duration decreased, maximum heat release rate indicated high, and concentration of NOx and exhaust smoke opacity is decreased, as function of water and methanol content y was higher.