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김덕줄,최동석,황순철 釜山大學校生産技術硏究所 1999 生産技術硏究所論文集 Vol.56 No.-
가솔린 와류형 고압 인젝터로부터 분사된 연료의 증발 거동을 exciplex 형광법을 사용하여 조사하였다. exciplex 형광법을 적용하기 위해 용매로 헥산, 참가제로 플루오로벤젠과 DEMA를 체적비로 각각 89%, 2%, 9% 혼합하였다. 결과로서 증발조건과 비증발조건에서 액상과증기상의 신호를 확인하였고, 분사후 경과시간에 따라 각각의 상의 공간분포의 변화를 측정하였다. 분무의 축방향으로의 증발보다는 분무반경방향으로의 증발이 더 활발히 진행되었다. 또한 순수한 증기상만이 차지하는 면적은 분사기간의 1/3지점에서 액상의 면적과 같아졌으며 그 이후는 급격히 증가하였다. This work was performed to provide qualitative information on the vaporization of fuel using exciplex fluorescence method in a spray from high-pressure swirl injector. Dopants used were 2% fluorobenzene and 9% DEMA(diethyl-methyl-amine) in 89% solution of hexane by volume respectively. As a result, liquid and vapor phases were compared under both evaporating and non-evaporating conditions, and each phase was illustrated with time after injection. Vaporization along the radial direction had larger activity than along the axial direction. The area of only vapor phase was approximated to that of liquid phase at about 1/3 of injection duration time, and after that time, it was greatly incrased.
A New Flame-Stabilization Technology for Lean Mixtures
Kim, Duck-Jool,Choi, Gyung-Min The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.4
The development of a low-pollution burner is important for saving energy and preserving the environment. A low-pollution burner can be produced by lean-mixture combustion and general combustion technology. The flammable limit of premixed flame is narrower than that of diffusion flame. Producing a lean mixture of fuel results in an effective combustion condition, which in turn produces high load and low pollution. In this study, it was found that the influx of $Q_2$ had an effect on extending the lean flammable limits and flame stabilization in a doubled jet burner. And the flame, consisting of small eddies, can be stabilized by the nozzle neck phenomena.
Choi, Dong-Seok,Kim, Duck-Jool,Hwang, Soon-Chul The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.10
The effects of ambient conditions on vaporizing sprays from a high-pressure swirl injector were investigated by an exciplex fluorescence method. Dopants used were 2% fluorobenzene and 9% DEMA (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to examine the behavior of liquid and vapor phases inside of vaporizing sprays, ambient temperatures and pressures similar to engine atmospheres were set. It was found that the ambient pressure had a significant effect on the axial growth of spray, while ambient temperature had a great influence on the radial growth. The spatial distribution of vapor phase at temperatures above 473K became wider than that of liquid phase after half of injection duration. From the analysis of the area ratio for each phase, the middle part (region II) in the divided region was the region which liquid and vapor phases intersect. For liquid phase, fluorescence-intensity ratio was greatly changed at lms after the start of injection. However, the ratio of vapor phase was nearly uniform in each divided region throughout the injection.
Effects of Piston Shapes and Intake Flow on the Behavior of Fuel Mixtures in a GDI Engine
Jeong-Jung Kang,Duck-Jool Kim 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.12
The purpose of this study is to investigate the stratification of fuel vapor with different in-cylinder flow, piston cavity and injection timings in an optically accessible engine. Three different piston shapes that are F (Flat), B (Bowl) and R (Re-entrance) types were used. The images of liquid and vapor fuel were captured under the motoring condition using Laser Induced Exciplex Fluorescence technique. As a result, at early injection timing of 270° BTDC, liquid fuel was evaporated faster by tumble flow than swirl flow, where most of fuel vapor were transported by tumble flow to the lower region and both sides of cylinder for the F-type piston. At late injection timing of 90° BTDC, tumble flow appears to be moving the fuel vapor to the intake side of the cylinder, while swirl flow convects the fuel vapor to the exhaust side. The concentration of mixture in the center region was highest in the B-type piston, while fuel vapor was transported to the exhaust side by swirl flow in F and R-type pistons. At the injection timing of 60° BTDC, the R -type piston was better for stratification due to a relatively smaller bowl diameter than the others.
Effects of Piston Shapes and Intake Flow on the Behavior of Fuel Mixtures in a GDI Engine
Kang, Jeong-Jung,Kim, Duck-Jool The Korean Society of Mechanical Engineers 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.12
The purpose of this study is to investigate the stratification of fuel vapor with different in-cylinder flow, piston cavity and injection timings in an optically accessible engine. Three different piston shapes that are F(Flat), B(Bowl) and R(Re-entrance) types were used. The images of liquid and vapor fuel were captured under the motoring condition using Laser Induced Exciplex Fluorescence technique. As a result, at early injection timing of 270 BTDC, liquid fuel was evaporated faster by tumble flow than swirl flow, where most of fuel vapor were transported by tumble flow to the lower region and both sides of cylinder for the F-type piston. At late injection timing of 90 BTDC, tumble flow appears to be moving the fuel vapor to the intake side of the cylinder, while swirl flow convects the fuel vapor to the exhaust side. The concentration of mixture in the center region was highest in the B-type piston, while fuel vapor was transported to the exhaust side by swirl flow in F and R-type pistons. At the injection timing of 60 BTDC, the R-type piston was better for stratification due to a relatively smaller bowl diameter than the others.
Application of DFB Diode Laser Sensor to Reacting Flow (Ⅰ)
Gyung-Min Choi,Masashi Katsuki,Duck-Jool Kim 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.11
Diode laser sensor for measuring gas temperature and species concentration in combustion chamber was developed using 2.0 μm distributed feed back lasers. To evaluate the measurement sensitivity of diode laser sensor system, CO₂ survey spectra near 2.0 μm were measured and compared with the calculated one. This diode laser absorption sensor was applied to measure gas temperatures in a premixed flat flame of CH₄-air mixture. Experimental results were in good agreement with the values by an R-type thermocouple within 6.12%. In addition, successful demonstration of measurement of gas temperature and species concentration in a soot flame showed the promising possibility of diode laser absorption sensors for practical combustion system with non-intrusive method.
Experimental Study on Spray Etching Process in Micro Fabrication of Lead Frame
Ji-Won Jung,Gyung-Min Choi,Duck-Jool Kim 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.12
The objective of this study is to obtain detailed information for the micro fabrication of lead frames by applying spray technology to wet etching process. Wet etching experiments were performed with different etching parameters such as injection pressure, distance from nozzle tip to etched substrate, nozzle pitch and etchant temperature. The characteristics of single and twin spray were measured to investigate the correlation between the spray characteristics and the etching characteristics. Drop size and velocity were measured by Phase- Doppler Anemometer<br/> (PDA). Four liquids of different viscosity were used to reveal the effects of viscosity on the spray characteristics. The results indicated that the shorter the distance from nozzle tip and the nozzle pitch, the larger etching factor became. The average etching factor had good positive correlation with average axial velocity and impact force. It was found that the etching characteristics depended strongly on the spray characteristics.<br/>