• 한국항공운항학회지
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• 제15권4호
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• pp.1-8
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• 2007

Spray characteristics of a unlike triplet injector were investigated experimentally. Spray images and SMD of droplet were measured to evaluate the spray characteristics injected by liquid/gas combinations. G-L-G(Gas-Liquid-Gas), L-G-L(Liquid-Gas-Liquid) type of injector were used by changing the gas and liquid feed lines. The SMD graph shows that the droplet sizes decrease in the out of radial direction at a fixed gas Reynolds number. The SMD value of decreasing tendency shows that the more ethyl alcohol ratio increase, the more SMD value decrease.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.119-126
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• 2001

The effects of injection pressure and the distance between injectors on the droplet distribution characteristics of liquid spray for dual orifice type swirl injectors were experimentally investigated. The SMD distributions, volume concentration and Rosin- Rammler variation N of liquid spray droplets for water and a fuel were measured by using the laser diffraction particle sizer. The results of present study show that SMD decreases and spray angle increases as the injection pressure increases. The interaction of sprays from two injectors gives more uniform SMD distribution in the radial direction. As the distance between two injectors increases, SMD that is measured in the interacting region increases. The effect of viscosity on the droplet distribution in the interacting region is greater than the that of surface tension of liquid.

• 한국분무공학회지
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• 제19권4호
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• pp.167-173
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• 2014

The spray characteristics of Gas-Centered Swirl Coaxial Injector was investigated that there were different characteristics with or without gas flow. As gas flow was accelerated, the momentum of gas was transferred to the momentum of liquid in the low liquid Reynolds number. Therefore, the axial velocity of liquid was increased and the measured value was smaller than without gas flow. However, in the high momentum flux ratio, the momentum transfer hardly occurred and the results had constant values. As the recess length was increased, the mixing area of gas and liquid also was increased, the results were decreased.

• 한국분무공학회지
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• 제7권1호
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• pp.36-42
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• 2002

The objective of this investigation was to obtain an excellent spray at the low injection pressure. When cavitation occurred in the nozzle hole the atomization of the liquid jet enhanced considerably. In this experiments, a acrylic nozzle which was installed the gap and installed the bypass in the nozzle hole was used to enhance the atomization of the liquid jet at the few injection pressure. The liquid flow in the nozzle hole was photographed by a transmitted light using a micro flash. The spray angle was measured by macroscope images of PMAS and the Sauter mean diameter was measured by PDA system. The pressure of the notate hole was measured by pressure transducer. It was found that enhanced atomization of the liquid jet at the low injection pressure was obtained by installing the gap and the bypass at the single hole nozzle.

• 한국분무공학회지
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• 제4권3호
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• pp.15-23
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• 1999

The use of LPG as clean fuel for Diesel engine is very attractive way to reduce soot and NOx emission. In this study, a numerical study has been done to know the transient behavior of LPG fuel in chamber pressures which is held at a pressure above (0.37MPa)and below(0.15MPa)the fuel vapor pressure. Results show that the vortex formed within the start of injection at the leading edge of the spray cone and was most apparent for 0.15MPa chamber pressure case. The high speed photographs and model results showed a narrower cone angle during the quasi-steady spray period at the 0.37MPa chamber pressure compared to the 0.15MPa case. And it can be shown that more realistic vaporization process is necessary to predict the spray length well.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.288-291
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• 2004

본 논문은 고압조건에서 동축 와류형 분사기의 분무특성 파악을 위한 연구로서 3종류의 분사기가 사용되었으며, 함몰길이와 연료 분사기의 형태에 따른 분무특성을 확인하였다. 또한, 실제 연소기에 서 발생되는 연소압력과 수류 실험에서의 압력 상사조건을 계산하여 실험을 수행하여 분사압에 따른 유량변화, 분무각, 질량분포, 평균 액적크기 등의 분무특성이 측정되었다.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.1-7
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• 2020

In orchard or crop-growing environments, pesticides are sprayed using various nozzles to prevent pests and improve productivity. Nozzles currently in use are restricted for use in multi-purpose environments, thus, it is necessary to develop new nozzles. In this study, new two-phase nozzles are proposed to improve the performance of the nozzle (flow rate, spray angle, spray particle size). The performance of the two-phase nozzles are predicted through the CFD analysis and the performance of the nozzles is compared with the experiment. The experimental results showed that the proposed two-phase nozzles are available at relatively low operating pressure condition and are capable of extensive spray particle size control. Thus, the proposed nozzles are expected to be available in various orchard environments.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.89-95
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• 2001

Recently GDI(Gasoline Direct Injection) engine is spotlighted to achieve higher thermal efficiency under partial loads and better performance at full loads. To realize this system, it is essential to make both stratified combustion and homogeneous combustion. When compared to PFI(Port Fuel Injection) engine, GDI engine needs more complicated control and optimal design with injection system. In addition, spray pattern must be optimized according to injection timing because ambient pressure in combustion chamber is also varied. Thus spray structure should be analyzed in details to meet various conditions. In this experimental study, two types of visualization system were developed to simulate compression stroke and intake stroke, respectively. With an increase of the ambient pressure, the penetration length tends to decrease due to rising resistance caused by the drag force of the ambient air. Spray characteristics impinged on the piston has a significant effect on mixture stratification around the spark plug. These results provide the information on macroscopic spray structure and design factors far developing GDI injector.

• 대한기계학회논문집
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• 제17권12호
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• pp.3179-3186
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• 1993

The study on the spray characteristics of TBI(Throttle Body Injection) injector has been carried out in this paper. The objective of this study is to improve the performance of TBI injector. The increase in the injection pressure and the utilization of assisted air are considered. The spray patten of TBI injector take the hollow-cone shape with $60^{\circ}~70^{\circ}$ spray angle regardless of injection pressure and injection pulse width. SAMD(Sauter Mean Diameter) of water in TBI injector are 510-$550{\mu}m$ and 310-$370{\mu}m$ respectively when injection pressures are $0.75 kgf/cm^{2}$ and $2.8 kgf/cm^{2}$. Then SMD of gasoline is estimated 380~$410{\mu}m$ and 230~$280{\mu}m$ respectively. The improvement of spray characteristics in TBI injector can be obtained with assisted air. If $W_{A}/W_{L}$ was over 0.2, SMD of water can be made under $50{\mu}m$.

• Journal of Mechanical Science and Technology
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• 제16권2호
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• pp.235-245
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• 2002

The present article aims to perform numerical calculations for inter-spray impingement of two diesel sprays under a high injection pressure and to propose a new hybrid model for droplet collision on the basis of literature findings. The hybrid model is compared with the original O'Rourke's model, which has been widely used for spray calculations. The main difference between the hybrid model and the O'Rourke's model is mainly in determination of the collision threshold condition, in which the preferred directional effect of droplets and a critical collision radius are included. The Wave model involving the cavitation effect inside a nozzle is used for predictions of atomization processes. Numerical results are reported for different impingement angles of 60°and 90°in order to show the influence of the impinging angle on spray characteristics and also compared with experimental data. It is found that the hybrid model shows slightly better agreement with experimental data than the O'Rourke's model.