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최동석,김덕줄,고장권,Choi, Dong-Seok,Kim, Duck-Jool,Ko, Chang-Kwon 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.8
The disintegration process of initial spray from high-pressure swirl injector was investigated at different injection pressures. The transient breakup phenomena that were difficult to observe at high injection pressure were easily observed at the low injection pressure of 0.4MPa. The effect of fuel remained inside a nozzle hole volume on the penetration of initial spray was also investigated. The disintegration process of initial spray could be classified four regions: the formation of mushroom shape, the first collision, the second collision, and the development of spray, The liquid film of cup shape was particularly found in the second collision region, and the growth ratio of its length and width at low and high injection pressures were compared.
강동완,황순철,김덕줄,Kang, Dong-Wan,Hwang, Chul-Soon,Kim, Duck-Jool 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.12
The purpose of this study is to obtain the information about the development process of GDI spray. To acquire the characteristics of GDI spray, the computational study of hollow cone spray for high-pressure swirl injectors was performed. Several hybrid models using the modified KIVA code have been introduced and compared. WB model and LISA model were used for the primary breakup, and DDB and APTAB models were used for secondary breakup. To compare with the calculated results, the experimental results such as cross-sectional images and SMD distribution were acquired by laser Mie scattering technique and Phase Doppler Analyzer respectively. The results show that LISA+APTAB hybrid model has the best prediction for spray formation process.
디젤연소실에서 새로운 충돌분무 형성에 대한 수치적 고찰
류성목,차건종,김덕줄,박권하,Ryoo, Sung-Mok,Cha, Keun-Jong,Kim, Duck-Jool,Park, Kweonha 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.11
The objective of this study is to establish geometric guidelines for design of impaction parts prepared for removing undesirable effects of fuel deposition on a wall in small direct-injection diesel engines. In order to get the guidelines a new wall geometry is introduced and assessed, which has a flat top and a slant edge. The size of the flat top and the angle of the slant edge are varied and tested in same chamber condition, then their effects on spray dispersions and drop sizes are discussed. The results show that the case of 3.0mm flat top and $60^{\circ}$ edge angle gives the best spray characteristics for a small combustion chamber in the test conditions chosen in this paper.
정지원,차건종,김덕줄,Jung, Ji-Won,Cha, Keun-Jong,Kim, Duck-Jool 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.10
The objectives of this study was to investigate the spray characteristics of single spray and twin spray in the overlap region such as mean axial velocity, mean radial velocity, mean droplet size and probability density function of droplet size. A phase doppler anemometer was used as the measurement system for droplet size and velocity. In case of single spray, injection pressure was varied from 0.2MPa to 0.7MPa. Mean axial velocity, mean radial velocity and droplet size were decreased as the distance below nozzle tip was increased. In case of twin spray, the spray characteristics were measured by varying the distance between two nozzles from 127mm to 155mm. In the overlap region, the boundary of the overlap region was determined by obtaining the distribution of mean axial and radial velocity. Droplet size was increased as the distance from nozzle tip was increased. It was found that the distribution of droplet size for twin spray in the overlap region was different to single spray.
송홍종,차건종,김덕줄,Song, Hong-Jong,Cha, Keun-Jong,Kim, Duck-Jool 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.6
The emission in the exhaust gas from diesel engine is effected by the fuel spray characteristics. The spray of D.I. diesel engine impinges on a piston cavity and a cylinder wall. It is very important to know exactly the distribution and behavior of the spray inside cylinder. The objective of this study is to develop more accurate evaporation model. The EPISO code was used to analyze the flow characteristics in the engine. The Wakil model and the Faeth model are applied to the EPISO code to analyze the behavior of impinging spray. And also experimental and numerical analysis were carried out. The spray behavior characteristics were investigated by changing injection pressure, ambient pressure and temperature. The behavior of impinging spray was strongly effected by the change of ambient pressure and temperature. The effects of evaporation and rebounding droplet should be considered.
분위기 온도에 따른 충돌 분무의 거동에 대한 실험 및 수치적 연구
심영삼,최경민,김덕줄,Shim, Young-Sam,Choi, Gyung-Min,Kim, Duck-Jool 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.4
The numerical study on behavior of impinging spray from high-pressure swirl injector under various ambient temperatures was performed by using spray vaporization model and spray-wall impingement model implemented in modified KIVA code, and these spray models were estimated by comparison with experimental results. To compute the spray-wall impingement process, the Gosman model, which is based on the droplet behavior after impingement determined by experimental correlations, was used. The modified Abramzon and Sirignano model, that includes the effects of variable thermodynamic properties and non-unitary Lewis number in the gas film, was adapted for spray vaporization process. The exciplex fluorescence measurements were also conducted for comparison. The experimental and numerical analysis were carried out at the ambient pressures of 0.1 MPa and at the ambient temperature of 293 K and 473 K, and the spray characteristics, such as spray-wall impingement process, gas velocity field, SMD and vapor concentration, were acquired. It was found that the impinging spray develops active and SMD is small at vaporization conditions.
최동석,류경훈,차건종,김덕줄,Choi, Dong-Seok,Ryu, Kyung-Hoon,Cha, Keun-Jong,Kim, Duck-Jool 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.10
High-pressure swirl injectors have usually been employed in Gasoline direct injection engines due to their spray characteristics and the feasibility of their control. Thus the microscopic characteristics of high-pressure swirl spray were investigated by PDA. The correlation between axial and radial velocities and the correlation between droplet size and axial velocity were examined with different axial and radial positions. Two dimensional droplet velocity and its number distribution with size-classified droplets were illustrated. The mean droplet velocity and its SMD were also analyzed at the center of spray, the position having maximum mean axial velocity, and the spray periphery using time dividing method. Finally, the structure of high-pressure swirl spray was presented with the size distribution and velocity profile of droplets.
분사시기와 피스톤 형상에 의한 연료 증기상의 공간분포에 관한 연구
강정중(Jeong-jung Kang),김덕줄(Duck-jool Kim) 한국자동차공학회 2002 한국자동차공학회 지부 학술대회 논문집 Vol.2002 No.3
This work is to investigate the spatial distribution of fuel vapor phase with different injection timing and piston cavity in a optically accessible engine. Two dimensional spray fluorescence image of fuel vapor phase was captured under the motoring condition using LIEF method. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. To generate swirl motion of intake flow, mask was installed at the inlet of the intake port. Three different piston types, F, Band R-type were used. Four injection timings were set at BTDC 90˚, 80˚ ,70˚ , and 60˚ . At a fuel injection timing of BTDC 90˚ , fuel-rich mixture level in the center region was highest in a B-type piston, while fuel vapor was transported to the exhaust valve by swirl flow in F, R-type pistons. At a fuel injection timing of BTDC 60˚ , R-type piston was better in stratification than the others. It is found that R-type piston was suitable under enhanced swirl ratio condition.
DI 가솔린 기관에서 분무의 충돌 거리가 연료의 증발 거동에 미치는 영향
김동욱(Dong-Wook Kim),강정중(Jeong-Jung Kang),최경민(Kyung-Min Choi),김덕줄(Duck-Jool Kim) 한국자동차공학회 2004 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
This study was performed to investigate the effect of behavior of liquid and vapor phase of fuel mixtures with different impingement distance in a optically accessible chamber. The images of liquid and vapor phase were measured under motoring and non-motoring condition. Exciplex fluorescence method were used. Experiment was performed under non-motoring condition. This results were compared with a motoring condition at the same time of injection. Two dimensional spray fluorescence images of liquid and vapor phase were acquired to analyze spray evaporative behavior and fuel distribution of cylinder. The images of liquid and vapor distributions are compared with impaction distance. Two impaction distance were Z=46.7mm and Z=70mm. At impaction distance of Z=46.7, fuel-rich mixture exist in the cavity center region. The concentration of fuel was richer at the Z=46.7mm than the Z=70mm.