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하이브리드 차량용 배터리계 냉각시스템의 풍량 개선에 관한 연구
이기수(Geesoo Lee),김현철(Hyunchul Kim),허형석(Hyungseok Heo),김성철(Sungchul Kim),원종필(Jongphil Won),권대복(Daebok Kwon) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The aim of this paper was to investigate fluid dynamic behavior characteristics, and effectively to design of air flow rate of the BAT/INV for hybrid electric vehicles (HEV). The BAT/INV for HEV installed in the luggage space of the vehicle and controlled by the battery monitoring system should operated in suitable thermal environmental conditions by means of air supply system. The analysis of the BAT/lNV cooling system has been peformed by applying the computational fluid dynamics (CFD) code, Fluent, to the solution of the 3-D turbulent flow fields. As a results, at design operating condition, air flow rate of the BAT/INV cooling system with the enhanced blower model increased by 30.8%, Q=162. 7 ㎥/h, comparison to it with the base blower model and the efficiency of the blower motor was predicted about 69.0%. In addition to, to minimize pressure loss of the system, the design of the air duct between the BAT/INV was improved.
자동차 워터펌프 밸런스 홀 직경이 수력성능 및 축추력에 미치는 영향
이기수(Geesoo Lee),허형석(Hyungseok Heo),김현철(Hyunchul Kim),오창복(Changbok Oh) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.3
The aim of this paper was to investigate the fluid dynamic behavior of the automotive closed type water pump with balance hole in order to evaluate and justify its overall hydraulic performance and, in particular to analyze the effects of the balance hole on the reduction of hydraulic flow force of it. The analysis has been peformed by applying the commercial computational fluid dynamics (CFD) code, Fluent, to the solution of the 3-D turbulent flow fields of automotive closed type water pump. The reliability of the employed analysis was demonstrated by the comparison between numerical result and experimental data. Although, hydraulic head of the closed type water pump with 3㎜ diameter of balance hole decreased by 1.1%, axial flow force was effectively reduced by 13.3%, comparison of it with no hole at design point.
다단 자동변속기용 유압 비례제어 솔레노이드 밸브의 CFD 해석
이기수(Geesoo Lee),김현철(Hyunchul Kim),성형진(Hyungjin Sung),허형석(Hyungseok Heo),이현우(Hyunwoo Lee) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
Three-dimensional numerical simulations were carried out to investigate the flow dynamic behavior and pressure characteristics of a variable force solenoid (VFS) valve used in automatic transmissions. To visualize the dynamic movement of the spool, a moving mesh with dynamic layering meshes for varying boundary conditions was employed. The motional direction and the speed of the spool were taken into account in the modeling of the VFS valve. The results of Model D, which takes into account both leakage and notches, indicate that there is a linear pressure response in the range of valve overlap and that there are smooth pressure control characteristics in the range of the two notches. Although the effects of magnetic materials were not included, the VFS with a spool was shown to have an unavoidable and unique hysteresis. This hysteresis can be minimized or maintained at low levels by adjusting the relation between the notch depth and the characteristic length.
사각 웨이브 형상을 갖는 판형 플라스틱 챠지에어쿨러의 방열성능 설계
이기수(Geesoo Lee),허형석(Hyungseok Heo),김현철(Hyunchul Kim),이승주(Seungjoo Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This study had dealt with the heat transfer characteristics of the automotive charge air cooler which had tubes of rectangular wave form. This study compared and investigated the characteristics as the number of tubes, the pitch and depth of the wave form of the tube on the basis of same core size. The proposed analysis was performed by applying the commercial fluid dynamics(CFD) code, Fluent 6.2, to the solution of 3-D turbulent flows of the plastic charge air cooler. It was found out that both heat transfer characteristics and charge air side pressure drop were linearly increased by severity factor for one step of plastic plate charge air cooler. In addition to, heat transfer performance of the plastic plate charge air cooler assembly with 36 steps of tubes was achieved by 6,850㎉/h at design point.
1-D Nozzle Flow Model을 이용한 DME 인젝터 노즐 홀 설계
이기수(Geesoo Lee),김대현(Daehyun Kim),김현철(Hyunchul Kim),정수진(Soojin Jung) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
The 1-D nozzle flow model was used to design the injector nozzle holes and to obtain the initial spray conditions for di-methyl Ether(DME) in a 3L diesel common-rail system. In order to deliver the same amount of energy to that provided by diesel at low injection pressure, 40 ㎫, the injector for DME needs larger diameters of nozzle holes and SAC volume at same injection period. In addition to, the lift of a needle should be increased, and the diameter should be increased to keep the minimum flow area ratio. Although the vapor pressure of DME is lower than that of diesel, the condition of cavitation inception for DME was delayed due to the decreased injection pressure. DME showed higher discharge coefficients and effective nozzle exit diameters in comparison with diesel owing to low injection pressure and expanded nozzle diameters. Finally, the spray simulations were performed to investigate spray characteristics of the injection for diesel and DME.
5속 A/T용 자동변속기 토크컨버터 댐퍼클러치 슬립제어가 슬립율과 연비에 미치는 영향
이기수(Geesoo Lee),김덕중(Deokjung Kim),김현철(Hyunchul Kim),나병철(Byungchul Na),허형석(Hyungseok Heo),이호길(Hogil Lee),장재덕(Jaeduk Jang) 한국자동차공학회 2009 한국 자동차공학회논문집 Vol.17 No.3
The objective of this paper was to investigate the slip rate and the slip frequency number of damper clutch of torque converter in 2.4L passenger vehicle with 5-speed A/T and analyze the effect of slip control and control strategy on driving characteristics and the fuel economy. The newly developed torque converter with the more durable wet friction material and the slip-controlled damper clutch system, the DCC system, was installed, which was easily compatible and amendable of the lock-up clutch of the base system. The vehicle has been tested on the fuel economy modes such as FTP-75, HWFET and NEDC (ECE15+EUDC) driving cycle at chassis dynamometer. The DCC mode (Ⅱ), of which the control strategy had both the lock-up and the slip-controlled clutch, and the DCC mode (Ⅰ) with full slip-controlled clutch were compared with the base system with only the lock-up clutch. As the research result, comparison to base system, the fuel consumption of the vehicle with the DCC control (Ⅱ) was effectively improved by 6.6% and 7.7% on FTP-75 and NEDC mode.
이기수(Geesoo Lee),허형석(Hyungseok Heo),김현철(Hyunchul Kim) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
This paper presents the design of shell and tube heat exchangers with round tubes and spiral enhanced tubes considering a pumping power. Since the pumping power was considered as a design requirement, the more pressure drop, the smaller the mass flow rate from the relation of it. Therefore, the performance of heat exchanger could be optimized under a given condition. The design was carried out to determine friction drop and heat transfer characteristics of spirally enhanced tubes, which have various geometrical parameters, including a spiral number and a spiral angle. The results showd that overall heat transfer coefficient of the spiral tubes(θ<SUB>s</SUB>=60°, N<SUB>s</SUB>=4, d/D<SUB>h</SUB>=1/6) was 3 times more than that of the round tubes in the turbulent flow. Heat transfer rate of the heat exchanger with the spiral tubes of 12 was 443.4W and about 3 times more than that with the round tubes.