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윤욱현(Wook-Hyeon Yoon),박종일(Jong-Il Park),정성수(Sung-Soo Jung),김대웅(Dae-Woong Kim),하은(Eun Ha) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Numerical studies on optimal design of combustion system for high-speed diesel engine, which is mainly used for power generation or ship propulsion, have been carried out to meet the target value of fuel oil consumption and IMO(International Maritime Organization) Tier2 NOx regulations. The spray visualization experiment was performed in the constant-volume high-pressure chamber to clarify the numerical results on the spray characteristics of the spray angle and penetration for medium-speed diesel engine having the same bore size. The intake/exhaust valve timing and turbocharger specifications were determined from the results of 1-D performance analysis. The nozzle configurations of the unit injector, fuel injection rate, piston bowl shape and compression ratio were determined from the results of 3-D in-cylinder combustion analysis. The intake swirl port geometry was developed from the results of 3-D flow analysis to improve the rate of fuel-air mixing and the velocity of diffusion flame for the reduction of fuel oil consumption. Finally, engine performance of the combustion system designed by numerical analysis was verified from the experimental results.
대형 디젤 엔진의 연료 노즐에 따른 3차원 연소특성 연구
윤욱현(Wook-Hyeon Yoon),김기두(Ki-Doo Kim),하지수(Ji-Soo Ha),강상립(Sang-Lip Kang) 한국마린엔지니어링학회 2004 한국마린엔지니어링학회 학술대회 논문집 Vol.2004 No.-
Numerical simulations have been carried out to investigate the effect of fuel spray angle on the combustion characteristics of the large diesel engine, 6S90MC-C. Spray and combustion phenomena were examined numerically using FIRE code. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation processes. Predictions on the cylinder peak pressure and NOx emission were first verified with the experimental data to confirm the reliability of numerical calculations. The comparison results showed good agreements within the range of 2 bar and 4.2% respectively. Finally, the effects of fuel spray angle on the engine performance were investigated numerically to find the optimum spray angle considering fuel consumption, NOx emission and heat flux of the combustion chamber wall. It was concluded that the case of the only one injector hole having the opposite direction from swirl was the best one for engine performance.
1.7 MW급 PPS(Packaged Power Station)에 대한 환기유동 해석
윤욱현(Wook-Hyeon Yoon),하지수(Ji-Soo Ha),이영식(Young-Sik Lee) 한국마린엔지니어링학회 2003 한국마린엔지니어링학회 학술대회 논문집 Vol.2003 No.-
The computational study of ventilation air flow in 1.7 MW PPS(Packaged Power Station) is carried out to validate the characteristics of heat transfer and flow in container box. To blow the open air into the PPS, four ventilation fans are located in the axial direction and to stop out the noise of a engine and generator, ventilation holes are pierced at the lower part of the inside wall and at the upper part of the outside wall of the container box. The releasing heat sources in container box are generator and engine block. To measure the surface temperature of engine block, infrared camera was used and the temperature of it was applied to boundary conditions. To approximate the heat pickup from the radiator core surface, the heat flux inside the radiator is calculated and added to the energy equation as an energy source terms. Instead of geometrically modeling the fan blades, the momentum generated by the fan is derived and added to the momentum equation as source terms. We analyzed three computational cases with the direction of air flow and recommend case 3 in this study. Also, experiment for case 1 has been carried out and the results are compared with the computational results. Reasonable agreement was found, which suggested that the employed numerical model had its credibility in actual PPS ventilation air flow.
연료분사 노즐 형상이 선박용 중형 디젤 엔진의 NOx에 미치는 영향 연구
윤욱현(Wook-Hyeon Yoon),김병석(Byong-Seok Kim),류승협(Sung-Hyup Ryu),김기두(Ki-Doo Kim),하지수(Ji-Soo Ha) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-
Multi-dimensional combustion analysis and experiment has been carried out to investigate the effects of the injector nozzle hole diameter and number on the NOx formation and fuel consumption in HYUNDAI HiMSEN engine. The behavior of spray and combustion phenomena in diesel engine was examined by FIRE code. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation. Wallfilm model suggested by Mundo, et al. and auto-ignition model suggested by Theobald and Cheng were adopted to investigate the spray-wall interaction characteristics and ignition delay. The information of spray angle and spray tip penetration length was extracted from fuel spray visualization experiment and the fuel injection rate profile was extracted from fuel injection system experiment as an input and verification data for the combustion analysis. Next, the nine different nozzle configurations were simulated to evaluate the effect of injector hole diameter and number on the NOx formation and fuel consumption.
단일 영역 모델 열발생율 계산 방법의 개선에 관한 연구
김기두,윤욱현,하지수,류승협,Kim Ki-Doo,Yoon Wook-Hyeon,Ha Ji-Soo,Ryu Seung-Hyup 한국마린엔지니어링학회 2004 한국마린엔지니어링학회지 Vol.28 No.7
Accurate heat release analysis of cylinder pressure data is important for evaluating performance in the development of diesel engine However, traditional single zone first law heat release model(SZM) has significant limitations due to the simplified assumption of uniform charge and neglecting local temperature inside cylinder during combustion process. In this study. heat release rate based on single zone heat release model has been evaluated by comparison with computational analysis results using Fire code which is based on multi-dimensional model(MDM). To overcome limitations due to simplicity of single zone assumption. especially the influence of specific heat ratio on gross heat release has been esteemed and newly suggested were the equation $\gamma$= $\gamma$(${T/T}_{max}$) which describes the variations of gases thermodynamic properties with mean temperature and maximum mean temperature inside cylinder Single zone heat release model applied with this equation is shown to give very good results over whole range of operating conditions when compared with computational analysis results based on multi-dimensional model.
대형 디젤 엔진의 연료 분사 노즐 형상이 NOx 발생량 및 연료소비율에 미치는 영향 연구
김기두,하지수,윤욱현,Kim Ki-Doo,Ha Ji-Soo,Yoon Wook-Hyeon 한국마린엔지니어링학회 2004 한국마린엔지니어링학회지 Vol.28 No.7
Numerical simulations have been carried out to investigate the effect of nozzle hole geometry on the combustion characteristics of the large diesel engine. 6S90MC-C. Spray and combustion phenomena were examined numerically using FIRE code. Wane breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation processes. Predictions on the cylinder peak pressure and NOx emission were first verified with the experimental data to confirm the reliability of numerical calculations. The comparison results showed good agreements within the range of 0.64% and 4.6% respectively. Finally, the effects of fuel spray angle and diameter on the engine performance were investigated numerically to find the optimum nozzle hole geometry considering fuel consumption, NOx emission and heat flux of the combustion chamber wall. It was concluded that the combustion gas recirculation in cylinder by changing fuel injection direction is an effective method to reduce NOx emission by about 10% with increasing fuel oil consumption, 1.4% in a large diesel engine.
디젤 기관 단일 영역 모델 열발생율 계산의 오차 보상에 관한 연구
류승협,김기두,윤욱현,하지수,Ryu Seung-Hyup,Kim Ki-Doo,Yoon Wook-Hyeon,Ha Ji-Soo 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.5
Accurate heat release analysis based on the cylinder pressure trace is important for evaluating combustion process of diesel engines. However, traditional single-zone heat release models (SZM) have significant limitations due mainly to their simplified assumptions of uniform charge and homogeneity while neglecting local temperature distribution inside cylinder during combustion process. In this study, a heat release analysis based on single-zone model has been evaluated by comparison with computational simulation result using Fire-code, which is based on multidimensional model (MDM). The limitations of the single-zone assumption have been estimated, To overcome these limitations, an improved model that includes the effects of spatial non-uniformity has been applied. From this improved single-zone heat release model (Improved-SZM), two effective values of specific heat ratios, denoted by ${\gamma}_V$ and ${\gamma}_H$ in this study, have been introduced. These values are formulated as the function of charge temperature changing rate and overall equivalence ratio. Also, it is applied that each equation of ${\gamma}_V$ and ${\gamma}_H$ has respectively different slopes according to several meaningful periods during combustion progress. The heat release analysis results based on improved single-zone model gives a good agreement with FIRE-code results over the whole range of operating conditions of target engine, Hyundai HiMSEN H21/32.
A Study of Optimization of NOx and SFOC on Medium Speed Diesel Engines
김기두(Ki Doo Kim),윤욱현(Wook Hyeon Yoon),하지수(Ji Soo Ha),김종석(Jong Suk Kim) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
An engine performance and combustion simulation has been carried out to investigate effective methods for NOx and specific fuel oil consumption(SFOC) reduction on medium speed diesel engines. The simulation results show that lowering the charge air temperature by 10℃, will decrease the NOx emissions by 10%. Also, Miller cycle is evaluated by performance simulation to reduce NOx emissions and SFOC at the same time. The fuel injection nozzle hole diameter, number and injection angle have been optimized to reduce NOx emissions through combustion simulation. The engine measurements have been performed to verify the performance and combustion results and to investigate the effects of the selected parameters on engine performance. The results of measurement indicate that Miller cycle and lower charge air temperature reduce 2.8% SFOC and 10% NOx emission. Fuel injection nozzle diameter 0.34㎜ results in 16.6% lower NOx emission than that of previous specification, 0.32㎜, slightly increasing SFOC, 1.3%.