• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.2040-2052
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• 2005

The present paper centers on the establishment of a quantified relationship between the macroscopic visual parameters of a Diesel spray and its most influential factors. The factors considered are the ambient gas density, as an external condition relative to the injection system, and nozzle hole diameter and injection pressure as internal ones. The main purpose of this work is to validate and extend the different correlations available in the literature to the present state of the Diesel engine, i.e. high injection pressure, small nozzle holes, severe cavitating conditions, etc. Five mono-orifice, axi-symmetrical nozzles with different diameters have been studied in two different test rigs from which one can reproduce solely the real engine in-cylinder air density, and the other, both the density and the pressure. A parametric study was carried out and it enabled the spray tip penetration to be expressed as a function of nozzle hole diameter, injection pressure and environment gas density. The temporal synchronization of the penetration and injection rate data revealed a possible explanation for the discontinuity observed as well by other authors in the spray's penetration law. The experimental results obtained from both test rigs have shown good agreement with the theoretical analysis. There have been observed small but consistent differences between the two test rigs regarding the spray penetration and cone angle, and thus an analysis of the possible causes for these differences has also been included.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.438-444
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• 2010

Crossflow에 미치는 영향을 최소화하면서 liquid Jet의 미립화 및 혼합특성을 향상시키기 위한 JICF의 분무 특성에 대해 실험적으로 연구하였다. Crossflow의 온도, 속도, 압력과 liquid Jet의 속도, 압력을 변화시키면서 crossflow와 liquid jet의 momentum ratio(q)의 변화에 따른 spray boundary (outer boundary, inner boundary)를 측정하고 실험식을 유도하여 선행연구자의 결과와 비교하였다. 특히, injector의 형상에 따른 jet penetration를 측정하여 dual orifice injector의 경우 전단 오리피스의 영향으로 후단 오리피스에서의 jet penetration은 single orifice injector 분사노즐과 비교할 때 약 18% ($L_h$=4 mm) 증가하는 것을 확인하였다.

• 한국분무공학회지
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• 제5권2호
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• pp.68-74
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• 2000

A this experimental study is executed to analyze spray characteristics for air-shrouded injector and 4hole 2spray type injector used in a gasoline engine. Since spray parameters including spray penetration and angle, SMD, and atomization characteristics are very important to increase the engine performance, the image processing algorithm for measuring the non-spherical spray diameter is developed. Spray characteristics of the air-shrouded injector(2hole 2spray) and 4hole-2spray injector are analyzed respectively by this digital image processing method. Effective spray characteristics to injectors is derived from this experimentation and obtained the design guide for gasoline injector.

• 한국분무공학회지
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• 제9권1호
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• pp.30-36
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• 2004

The purpose of this study was to investigate the fuel spray characteristics that made most important at an homogeneous air fuel mixture, in a common rail direct injection type HCCI engine. As a study conducted relation which a back pressure and injection pressure are influenced to air fuel mixture characteristics, we tried to offer date even through we select suitable to a HCCI engine running condition of the fuel injection condition. To accomplish the study, to measure a injection rate of common rail type injector and to visualize and simulate a fuel spray was conducted. From the result of injection rate, a common rail injector was confirmed to appear a initial delay of 0.3msec and a latter period delay of 0.7msec. Therefore, real injection duration was determined by about 0.5msec increasing. From the result of fuel spray, the spray penetration was proportional to 1/4 exponent of atmosphere pressure. An experimental equation was deduced from the spray penetration of spray visualization experiment and the relation of injection duration and penetration was estimated in HCCI engine using an experimental equation.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.137-146
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• 1997

Spray characteristics of high pressure injectors for diesel engines have been experimentally studied with special emphasis on the effect of swirl. A constant volume chamber was rotated in order to generate a continuous swirl having the flow field of a solid body rotation, resulting in the linear dependance of the swirl number on the rotating speed of the chamber. Emulsified fuel is injected into the chamber and the developing process of fuel sprays is visualized. The fuel spray developing process in D.I. diesel engine was investigated by this liquid injection technique. The effect of swirl on the spray tip penetration is quantified through modelling. Results show that the spray tip penetration is qualitatively different for low and high pressure injections. For high pressure injection case, a good agreement is achieved between the experimental results and the modeling accounting the effect of swirl. For low pressure injection, a reasonable agreement is obtained. It is found that excessive swirl may cause adverse effect on spray dispersion during the initial combustion period since the spray can not be impinged on chamber wall.

• International Journal of Automotive Technology
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• 제6권3호
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• pp.215-219
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• 2005

Liquefied petroleum gas (LPG) has been used as motor fuel due to its low emissions and low cost. A liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray injecting from single hole injector. Two different test conditions are given, which are a fully developed spray case with various injection pressures and a developing spray case with ambient pressure variation. The LPG spray photographs are compared with the sprays of gasoline and diesel fuel at the same conditions, and the spray angles and penetration lengths are also compared, and then the spray behavior is analyzed. The LPG spray photos show that the dispersion characteristic depends very sensitively on the ambient pressure soon after injection. The spray angle is very wide in a low ambient pressure condition until the saturated pressure, but the angle is quickly reduced at the condition over the pressure. However, the down stream of the LPG spray shows much wider dispersion and less penetration than those of gasoline and diesel sprays regardless ambient pressure condition.

• 한국분무공학회지
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• 제12권2호
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• pp.101-107
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• 2007

The purpose of this study is to analyze spray and evaporation characteristics of DME fuel at the high pressure and temperature. For the numerical analysis of dimethyl ether(DME) fuel spray characteristics, hybrid breakup model was applied to the DME spray and its breakup process. In order to obtain experimental results for comparison with the predicted ones, the visualization of the spray evolution process was executed by using a Nd:YAG laser. Also, the numerical investigation was conducted by the two hybrid models for primary and secondary breakup of the DME spray. The primary breakup model was used the Kelvin-Helmholtz(KH) breakup model. In the secondary breakup process, Rayleigh-Taylor(RT) and Drop Deformation Breakup(DDB) model was applied. The results of this study provide the macroscopic characteristics of the spray such as spray tip penetration and cone angle, and prediction accuracy of the two hybrid model.

• 한국분무공학회지
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• 제10권1호
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• pp.35-42
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• 2005

The present study has numerically and experimentally investigated the spray behavior of liquid jet injected in subsonic cross-flow. The corresponding spray characteristics are correlated with jet operating parameters. The spray dynamics are known to be distinctly different in the three regimes: the column, the ligament and the droplet regimes. The behaviors of column, penetration and breakup of liquid jet have been studied. Numerical and physical models are base on a modified KIVA code. The primary atomization is represented by a wave model base on the KH(Kelvin-Helmholtz) instability that is generated by a high interface relative velocity between the liquid and gas flows. In odor to capture the spray trajectory, CCD camera has been utilized. Numerical and experimental results indicate that the breakup point is delayed by increasing gas momentum ratio and the penetration decreases by increasing Weber number.

• 한국자동차공학회논문집
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• 제5권6호
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• pp.120-127
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• 1997

A diesel engine is one of the major prime movers owing to its high thermal efficiency. But due to the recent attention for the environmental pollution, the emissions of diesel engine became a important problem. So it is needed to understand the characteristics of diesel spray injected into a combustion chamber. Because the diesel combustion is strongly controlled by a fuel spray injected into a combustion chamber. This study provides the informations for the diesel spray with the atmospere condition in combustion chamber by PMAS. As the result, the spray tip penetration and angle is increased with the increase of spray pressure and nozzle diameter. And the comparisions between the measured outline of the free-spray and the calculated model have been conducted and obtained the resonable results.

• 한국분무공학회지
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• 제17권4호
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• pp.178-184
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• 2012

The aim of this study was to compare the spray characteristics of a typical fuel (100% diesel, DME) and diesel-DME blended fuel in a constant volume combustion chamber (CVCC). The typical fuel (100% diesel, DME) and diesel-DME blended fuel spray characteristics were investigated at various ambient pressures (pressurized nitrogen) and fuel injection pressures using a common rail fuel injection system when the fuel mixture ratio was varied. The fuel injection quantity and spray characteristics were measured including spray shape, penetration length, and spray angle. Common types of injectors were used.