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직접분사식 가솔린엔진에서 피스톤 캐비티 형상이 연료 분무의 충돌과 거동에 미치는 영향
김동욱(Dongwook Kim),최경민(Gyungmin Choi),김덕줄(Duckjool Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This study was carried out to investigate the effects of piston cavity geometry on the spatial and temporal development of injected fuel sprays in a DI gasoline engine. The impingement and behavior of impinged spray is affected the stratification of fuel mixture. Thus, it is informative to understand in detail the behavior and distribution of fuel mixture after impingement in the cavity. Two dimensional spray fluorescence images of liquid and vapor phase were acquired to analyze the behavior and distribution of fuel mixtures inside cylinder by exciplex fluorescence method. To clarify the wall effect of the piston cavity, cavity wall angle were set to 30, 60 and 90 degrees, respectively. The results show that In the case of 30 degrees, the rolling-up moved from the impinging location to the round and fuel-rich mixture distributed at periphery of cylinder. In the case of 60 and 90 degrees, the rolling-up recircurated and accumulated in the cavity and fuel mixtures concentrated at center region. High concentrated fuel vapor phase was observed in the cavity with 90 degrees. From present study, it was found that the desirable piston geometry affected the fuel mixture stratification in a DI gasoline engine.
이젝터형 희석장치와 SMPS 시스템을 사용한 디젤 입자상 배출 물질의 크기분포 측정에 관한 연구
황순철(Soonchul Hwang),김덕줄(Duckjool Kim),윤성한(Sunghan Yun),한방우(Bangwoo Han),김용진(Yongjin Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
This study presents the characteristics of particle number and size distributions from the diesel exhaust. These were measured for various load and speed conditions of two different engines using ejector-type diluter sampling system. The sampled exhausts were analyzed by scanning mobility particle sizer(SMPS). Because the dilution leads to the particle transformations of nucleation and condensation when exhaust particles are cooled and diluted, to fine the effect of dilution temperature on the particle number and size distribution, the additional measurements under various dilution temperatures were performed. As a result of this study, it is found the ultrafine particle is very sensitive to the exhaust and dilution temperatures.
중공 원추형 연료 분무의 미립화 및 벽 충돌 과정에 대한 연구
심영삼(Youngsam Shim),최경민(Gyungmin Choi),김덕줄(Duckjool Kim) 한국자동차공학회 2006 한국 자동차공학회논문집 Vol.14 No.4
Numerical analysis about atomization and wall impingement process of hollow-cone fuel spray is performed by a modified KIVA code with hybrid model. The atomization process is modeled by using hybrid breakup model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model. The Gosman model, which is based on the droplet behaviors after impingement determined by experimental correlations, is used for spray-wall impingement process. The LIEF technique was used to compare the results with those of experiment. The calculations and experiments are carried out at the ambient pressures of 0.1 ㎫ and 0.5 ㎫ and the ambient temperature of 293K. It was found that the calculated results show satisfactory agreement with experimental ones.
GDI 분무의 벽 충돌 과정에 대한 실험 및 수치적 연구
심영삼(Youngsam Shim),최경민(Gyungmin Choi),김덕줄(Duckjool Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Experimental and numerical analysis about atomization and wall impingement process of hollow-cone fuel spray is performed by hybrid model and wall impingement model. The atomization process is modeled by using hybrid breakup model that is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model. The Gosman model, which is based on the droplet behaviors after impingement determined by experimental correlations, is used for spray-wall impingement process. The LIEF technique was used to compare the results with those of experiment. The calculations and experiments are carried out at the ambient pressures of 0.1㎫ and 0.5㎫ and the ambient temperature of 293K.
GDI 엔진용 고압 스월 인젝터의 초기 및 주 분무에 대한 수치적 연구
심영삼(Youngsam Shim),최경민(Gyungmin Choi),김덕줄(Duckjool Kim) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
The objective of this study is to analyze the pre spray and the main pray ofa high pressure swirl injector for GDI injector by using a hybrid breakup model. The hybrid breakup model is composed of Linearized Instability Sheet Atomization (LISA) model and Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model. The LISA model was used for primary breakup process and the APTAB model was used for secondary breakup process. The spray model was incorporated in three-dimensional computational fluid dynamic code (KIVA code). The exciplex fluorescence method was used for comparing the calculated results with the experimental ones. The experiment and the calculation were performed at the ambient pressures of 0.1 ㎫ and 0.5 ㎫ and the ambient temperature of 293K.
증발 조건에서 벽면 형상에 따른 충돌 분무 거동의 수치적 연구
심영삼(Youngsam Shim),김동욱(Dongwook Kim),최경민(Gyungmin Choi),김덕줄(Duckjool Kim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Numerical study on a spray-wall impingement process was performed under vaporization condition, and the effect of the ambient temperature on the film formation of wall was investigated. A detailed understanding of this process will help in designing injection systems and controlling the strategies to improve engine performance and exhaust emissions. The improved Abramzon model was used for vaporization process of the spray and the Gosman model was adopted for modeling of spray-wall impingement process. These model was implemented in the KIVA code. The calculated results of spray-wall impingement process was compared with experimental results. The ambient velocity field, the Sauter Mean Diameter and the generated fuel film on the wall, which are difficult to obtain by the experimental methods, were also calculated and discussed. It was found that the numerical results show good agreement with the experimental ones.