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CFD/FEM 에 의한 엔진 배기 매니폴드의 열피로 특성 해석
최복록(Boklok Choi),박재인(Jaein Park),장훈(Hoon Chang),박관흠(Kwanhum Park) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_3
This paper presents a numerical method for the engine exhaust manifold subject to severe cyclic thermomechanical loading. The analyses based on the geometry of the exhaust manifold, temperature dependent material properties as well as nonlinear stress-strain relationship, proper boundary conditions, and temperature distribution data equivalent to the thermal cycles. As a result of nonlinear thermal stress analysis, compressive plastic deformations occurred during heating process since the thermal expansion of the manifold was restricted by less expanded inlet flange and cylinder head. And, tensile stress remained when the manifold was cooled down to the ambient temperature. From these repetitions of heating and cooling, we can obtain the stress-strain hysteresis loop in a critical zone. The estimated plastic strain range was often used as the crack initiation criteria. This method was applied to assess the characteristics of the low cycle thermal futigue for the "A" engine exhaust manifold. The results show a good agreement between numerical analysis and experimental results.
김창현(Changhyun Kim),이강수(Kangsoo Lee),박재인(Jaein Park),백제현(Jehyun Baek) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
Diesel engine injector is used for spraying the fuel into the cylinder chamber. Complex phenomenon like cavitation occurs from small scale of injector nozzle and high pressurized fast flow field. Flow inside the nozzle affects whole engine performance including combustion and exhaust process, therefore understanding the flow inside the injector nozzle is very important. In the injector, the needle moves in vertical direction and controls the injection. Flow field inside the nozzle and nozzle outlet characteristics will be varied from the position of the needle. Because of small nozzle size and complex flow field, experimental approach is difficult. In this study, by using commercial code and mesh deformation technique, unsteady flow inside the nozzle and nozzle outlet characteristics can be analyzed. As a result, the complex flow field is placed inside the nozzle and especially, cavitation occurs at the upper side of nozzle inlet from the pressure drop below the vapor pressure. The characteristics at nozzle inside and outlet are varied as needle moves up and down. Subsequent processes, combustion and exhaust, can be predicted accurately by using the way discussed in this paper and to conclude, whole engine performance can be predicted and improved.
오일갤러리 유동을 고려한 디젤 엔진 피스톤 온도분포 예측
하응지(Eung-Ji Ha),문길민(Kilmin Moon),박재인(Jaein Park) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Control of piston temperature has become one of the important factor for a recent high power and high speed diesel engines. The temperature control for diesel engine piston is commonly achieved by piston cooling jet system with oil gallery flow. However, the oil flow and piston cooling characteristics in the oil gallery have not been understood accurately. Therefore, a numerical procedure has been developed to simulate unsteady oil flow in the piston oil gallery and to predict the piston temperature distribution with oil gallery flow. The predicted piston temperature distribution showed good agreement with measured data Parametric studies were performed to evaluate the influence of oil jet velocity, oil jet nozzle area and oil gallery exit area on the piston temperature. It is found that the average heat transfer coefficient of the oil gallery increased proportional to the amount of oil jet flow. The filling ratio of oil flow and the average piston temperature are converged as the oil flow rate increased.
클러치 내부 오일 유동해석 기법을 통한 오일 공급홀 최적화
김학기(Hakki Kim),송경(Kyoung Song),박재인(JaeIn Park),정연민(YeonMin Cheong),황동환(DongHwan Hwang) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The flow rate and the behavior of the automatic transmission fluid (ATF) from a input shaft to the clutch plates have been simulated as a three-dimensional and transient-state using the free surface method of commercial CFD code STAR-CD. During disengagement of the wet clutch plates, amount of heat energy dissipated by the lubricating oil that flow the nominalgap between the plates which have relative rotating speed. To supply the oil equally into the nominal clearances among the friction plates, a lay out of the lubrication passage hole configuration is very important. Since a hole configuration can be changed by the hole number, shape and the position at the hub, the optimization of the oil hole configuration is necessary. It is difficult to estimate the flow rate of the lubricating oil exactly at each part of the automatic transmission because of its structural complexity under rotating conditions. This paper suggest the oil hole configurations which can distribute the ATF uniformly around the multi-plates with the optimization method. From this result, we can obtain various information about the lubricating state at every part of the plates and can help our judgment of whether lubrication is sufficient
자동변속기 클러치 윤활 및 냉각해석을 통한 오일 홀 최적화
김학기(Hakki Kim),송경(Kyoung Song),박재인(Jaein Park),황동환(Dongwhan Hwang),김현석(Hyunsuk Kim) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
The flow rate of the automatic transmission fluid (ATF) from a input shaft to the clutch plates have been simulated as a three-dimensional and transient-state using the free surface method of commercial CFD code STAR-CCM+. During the disengagement of the wet clutch plates, amount of heat energy dissipated by the lubricating oil that flow the nominal gap between the plates which have relative rotating speed. To supply the oil equally into the nominal clearances among the friction plates, a lay out of the lubrication passage hole configuration is very important. Since the hole configurations can be changed by the hole number, shape and the position at the hub, the optimization of the oil hole configuration is necessary. It is difficult to estimate the flow rate of the lubricating oil exactly at each part of the automatic transmission because of its structural complexity under rotating conditions. This paper suggest the method that can estimate the optimal oil hole configurations which affect the temperature of the plates by using 1D ATF oil circuit simulation and the numerical thermal analysis program “clutchtherm” with the 3D CFD results. From this result, we can obtain various information about the lubricating state at every part of the plates and can help our judgment of whether lubrication is sufficient.
엔진 온도 평가와 열정산을 위한 통합 열전달 해석 기술
김태균(Taegyun Kim),문길민(Kilmin Moon),송경(Kyong Song),박재인(JaeIn Park) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
The increase of power density is limited by engine temperature. Engine component temperatures are an important consideration. because it will affect material strength and lubricating performance, therefore, it is of great importance tor engine designers to estimate component temperature in the early stage of engine development. In the present work, the conjugate heat transfer analysis of calculating heat transfer between head/block solid components and coolants was used. to estimate solid component temperature distribution and heat rejection to coolant. In particular. unsteady heat transfer simulation method of Intake/exhaust valve system were developed. The calculation results were presented and compared with experimental results to confirm the validity of this methodology. It is also applied to optimize engine cooling system through thermal balance.