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자동차 엔진 방열기의 냉각 성능 및 방열 면적 예측에 관한 연구
박찬국(C. G. Park),이종범(J. B. Lee),엄호룡(H. R. Eom),정우인(W. I. Chung) 한국자동차공학회 1997 한국 자동차공학회논문집 Vol.5 No.3
To maintain the reasonable temperature in the engine is very important to keep the steady com, bustion state of engine and to prevent increasing of lubricant consumption, deteriorating of lubri-cant, shortening of the life time of engine and decreasing of material strength.<br/> The method of energy balance for devided elements of radiator is considered to analyse the performance of radiator. The data of engine test and vehicle cooling tunnel test are applied to pro-gram for calculation of radiator outlet temperature, and this result is compared with outlet temperature of vehicle cooling tunnel test.<br/> As a result, the radiator outlet temperature by numerical analysis agrees well with that by experiment. It is concluded that this simulation program is available in developing the cooling system for a new car.<br/>
협착부가 존재하는 혈관의 유동 특성에 관한 수치 해석적 연구
정훈(H. Jung),박찬국(C. G Park) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Hemodynamics behavior of the blood flow is influenced by the presence of the arterial stenosis. If stenosis is present in an artery, normal blood flow is disturbed. In the present study, characteristics of steady and pulsatile flow of non-Newtonian fluid, the effects of stenosised geometry are analyzed by numerical simulation. One interesting point is that non-symmetric solutions were obtained at severity stenosis, although the stenosis and the boundary condition were all axisymmetric.
홍보영(B. Y. Hong),박찬국(C. G. Park) 한국전산유체공학회 2001 한국전산유체공학회지 Vol.6 No.4
Wind flow perturbations, recirculations and turbulence generated by buildings often dominate air pollutant distributions around buildings. This paper describes dispersion of contaminants in the vicinity of a building by solving the concentration equation based on previously simulated wind flow field. Turbulence closure is achieved by using the standard k-ε two-equation model. The paper shows application of the CIP method for solving a species concentration equation of contaminant gas around a rectangular building for two different sources under conditions of neutral atmospheric stratification. Results have been compared to the experimental data and the previous numerical results by hybrid scheme. The computational results of concentration profiles by the CIP method agree well with experimental data.
자연흡기식 디젤 기관의 연소와 매연 배출 특성에 관한 실험적 연구
정우인(W. I. Chung),박찬국(C. G. Park) 한국자동차공학회 1997 한국 자동차공학회논문집 Vol.5 No.4
We made a selection of engine operating conditions in the natural aspiration type diesel engine as load and speed. The effects on the power, smoke emission and cylinder pressure characteristics of these variations in operating conditions were observed experimentally.<br/> Also, the smoke emission was predicted by using the An-henius equation and empirical equation of the smoke emission was made. At the same time, the correlations between the combustion and smoke emission characteristic were examined.<br/> From the above results, it is clear that to prevent power dropping and to decrease exhaust fume when the conditions are changed, one should improve the intake system. To do this, the best way is to lower the air-fuel mixing ratio.<br/> We found that the parameters of the indicated mean effective pressure, maximum pressure and its location and combustion duration, etc. change the motion in accordance with the conditions described above. Also, we found that the variation of the pressure cycle comes from an amplified variation of the early part of process.<br/> From the analysis of comparing combustion and exhaust fume, the exhaust fume is produced at the latter time of combustion and decreased when the combustion ratio is higher. Also, we developed a special formula which can predict the exhaust fume value according to the engine load and speed.<br/>
가스와 입자가 혼합된 2상 유동에 관한 수치해석적 연구
정훈(H. Jung),최종욱(J. W. Choi),박찬국(C. G Park) 한국전산유체공학회 2001 한국전산유체공학회지 Vol.6 No.4
The phenomena of two-phase suspension flows appear widely in nature and industrial processes. Hence, it is of great importance to understand the mechanism of the gas-solid two-phase flows. In the present study, the numerical simulation has been approached by utilizing the Eulerian-Lagrangian methodology for describing the characteristics of the fluid and particulate phases in a vertical pipe and a 90° square-sectioned bend. The continuous phase(gas phase) is described by the Eulerian formulation and a K-ε turbulence model is employed to find mean and turbulent properties of the gas phase. The particle properties( velocity and trajectory) are then described by a Lagrangian approach and computed using the mean velocity and turbulent fluctuating velocity of the gas phase. The predictions are compared with measurements by laser-Doppler velocimeter for the validation. As a result, the calculated results show good agreements.
[디젤엔진부문] 분사각 및 스월 변화에 따른 디젤분무의 특성에 관한 수치 해석
정훈(H.Jung),차경세(K.S.Cha),박찬국(C.G.Park) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1999 No.11_1
In high-pressure diesel engine, the injected fuel spray impinges on the piston cavity surface due to the short distance between the injection nozzle and the cavity wall. The behavior of the impinging spray has the great influence on the dispersion of fuel, the evaporatioin, and the mixture formation process. In this study, the numerical simulation using the GTT code was performed to study the gas flows, the spray behaviors, and the fuel vapor distributions in the combustion of a OJ engine for variation of spray angle and swirl ratio.
분사각 및 스월 변화에 따른 디젤분무의 특성에 관한 수치 해석
정훈(H. Jung),차경세(K. S. Cha),박찬국(C. G. Park) 한국전산유체공학회 2000 한국전산유체공학회지 Vol.5 No.3
In high-pressure diesel engine, the injected fuel spray impinges on the piston cavity surface due to the short distance between the injection nozzle and the cavity wall. The behavior of the impinging spray has the great influence on the dispersion of fuel, the evaporatioin, and the mixture formation process. In this study, the numerical simulation using the GTT code was performed to study the gas flows, the spray behaviors, and the fuel vapor distributions in the combustion of a D.I engine for variation of spray angle and swirl ratio.