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확산 화염 화염소 모델을 통한 직접 분사식 가솔린 엔진의 배기 배출물 모델링
권혁선(Hyuksun Kwon),김주한(Joohan Kim),김규진(Gyujin Kim),민경덕(Kyoungdoug Min) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
DISI technology is considered to be an effective way for reducing CO2 emissions and improving fuel economy in gasoline engine. However, combustion process and emission characteristics of DISI engine are largely different from those of conventional gasoline engine, and even more resemble those of diesel engine due to the direct injection of the fuel. In this research, the emission production of DISI engine was modeled by combining flamelet models for diffusion flame. The detailed composition of species mass fraction in burnt gas was predicted by a diffusion flamelet model. According to the flamelet library approach, solution sets of steady flamelet equations were obtained at various scalar dissipation rate conditions. The resultant model were performed in three dimensional CFD simulations of practical engine geometry and showed good agreement with experimental data.
LPG 액상 분사 시스탬의 인젝터 노즐 내부 유동 측정과 LPG 분무 모델의 개발
권혁선(Hyuksun Kwon),최회명(Hoimyung Choi),김만식(Manshik Kim),민경덕(Kyounhdoug Min) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
LPG has been well known as a clean alternative fuel for vehicles. Recently, the new Liquid Phase LPG Injection(LPLI) system extends the limits of primitive LPG engine's power and improves load control property.<br/> In this study, internal flow of LPG fuel in visualization nozzles was investigated using back-light method and different flow patterns in each nozzles were examined. A nozzle model was developed assuming that the processes in the nozzle are isentropic and utilized to calculate initial conditions of spray model. Three-dimensional spray simulation was performed using Lagrangian method and the simulation results were compared with the expeimental results. As proportion of butane within the fuel and injection pressure was increased, more LPG fuel was observed in liquid phase. Comparing the results of nozzle model calculation with the images from visualization experiments, developed nozzle model was proved to be fairly<br/> reasonable and useful. Also, three-dimensional simulation results were agreed well wit<br/> experimental results in spray penetration length and velocity.
권혁선(Hyuksun Kwon),최회명(Hoimyung Choi),민경덕(Kyoungdoug Min),손진욱(Jin-Wook Son),김우태(Wootae Kim) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
To analyze the flow characteristics of engine exhaust port, a numerical approach was established. Computational meshes were generated part by part and boundary conditions were matched with the experimental environments. The CFD results agree well with the experimental results. Port geometry was varied by changing of the design parameters and the flow characteristics were observed at several view points. The flow coefficients were evaluated at each shape of exhaust port and the effect of design parameter was investigated. This approach distinguished important port shape parameters and the flow coefficients would be improved by modifying those parameters.
Premixed Combustion Model of SI Engine With Considering Burnt Gas Composition
Hyuksun Kwon(권혁선),Kyoungdoug Min(민경덕) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Conventional combustion models are suitable for predicting flame propagation for a wrinkled flamelet configuration. But they cannot predict the burnt gas composition. This causes the overestimation of burnt gas temperature and pressure. A modified method of combustion simulation was established to calculate the chemical composition and to investigate their ultimate fate in the burnt gas region. In this work, the secondary products of combustion process, like CO and H₂, were considered as important factors. A three-dimensional CFD program was used to simulate the turbulent combustion and a zero dimensional equilibrium code was used to predict the chemical composition of burnt gas. With this simple connection of zero and three dimensional calculation, more reasonable temperature and pressure values approaching the experimental result were predicted without additional time costs.
예혼합 및 확산화염 화염소 모델의 결합을 통한 직분식 가솔린 엔진의 연소 모델링
권혁선(Hyuksun Kwon),민경덕(Kyoungdoug Min) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.41
DISI(Direct Injection Spark Ignitoin) technology is considered to be an effective way for reducing emissions and improving fuel economy of SI engines. However, mixture preparation and combustion process in DISI engines are quite different from conventional PDF engines. In this study, the combustion process of DISI engine was simulated by a flamelet model based on the premixed flame propagation mechanism, but that took the triple-flame structure as a key element of partially premixed situation into account. The primary flame propagation was described by the flame area evolution model, which was modified and expanded for inhomogeneous charge, and a gasoline surrogate fuel and laminar flamelet approach was used to retain the detailed chemistry information. The secondary diffusion flame was modeled by a two-step reaction scheme of CO and H₂. The results of combustion simulations in a two-dimensional planar mesh and sectional engine mesh showed that the triple flame structure was well resolved into the combustion model and the effect of the charge stratification in the engine combustion chamber was effectively considered.
뜨임처리 온도에 따른 고장력강의 피로 및 기계적 물성평가
정연일(Younil Chung),권혁선(Hyuksun Kwon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In this study, after hot press forming and quenching process, the mechanical and fatigue properties of HPF steel produced by POSCO is evaluated precisely according to tempering temperature. Tensile, hardness and fatigue tests were performed at room temperature. As tempering temperature is increasing, the tensile strength and Vickers hardness values are decreasing, while the total elongation value is increasing. The increase rate of elongation between 200℃ and 350℃ tempering temperature is higher than other tempering ranges though the tensile strength decreases similarly. In this study, the HPF steel tempered at 250℃ shows the best result in the low cycle fatigue test.
고장력강 MAG 용접부 피로파손에 영향을 미치는 인자에 관한 연구
정연일(Younil Chung),권혁선(Hyuksun Kwon) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
The automotive chassis components are structural assemblies that support the engine, suspension, and steering components of vehicles. For the development of AHSS chassis components, the weld parts’ durability of them is very important. In this paper, the effect of torch angle, push angle, weld voltage, weld speed and gas is precisely analyzed. Fist of all, through the tensile tests of weld specimens, torch angle, push angle and weld speed are main factors to decide tensile strength. Because the relation between tensile strength and fatigue strength is proportional, it is assumed that torch angle, push angle, weld speed are the main factors to control fatigue life. Next, maintaining the same heat input level, the difference of fatigue life is investigated according to changing torch and push angle. The more torch and push angle are large, the more the fatigue life is long.
자동차용 샤시부품의 용접부 피로수명 향상 방안에 관한 연구
정연일(Younil Chung),권혁선(Hyuksun Kwon) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
The automotive chassis components are structural assemblies that support the engine, suspension, and steering components of vehicles. For the development of AHSS chassis components, the weld parts’durability of them is very important. In this paper, the effect of torch angle, push angle, weld voltage, weld speed and gas is precisely analyzed. Maintaining the same heat input level, the difference of fatigue life is investigated according to changing torch and push angle. The more torch and push angle are large, the more the fatigue life is long. In this study, Hot Spot Stress, HSS, is also measured precisely by using strain gages attached on the fatigue weld specimens. Toe angle is a main factor to control HSS of weld specimen. To enhance weld fatigue life of automotive components, it is necessary to make toe angle large.