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3L급 DME 커먼레일 시스템을 위한 인젝터 Seal과 분사 유량 개선
이기수(Geesoo Lee),신윤섭(Yunsub Sin),김현철(Hyunchul Kim),오세두(Sedoo Oh),정수진(Soojin Jeong),표영덕(Youngdug Pyo) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
The study on the improvement of injector seal and injection flow rate for developing a 3L di-methyl Ether(DME) common-rail system were performed. The nozzle flow model was used to design the injector nozzle hole and injection amount and rate were tested by diesel and DME test bench. In order to deliver the same amount of energy that provided by diesel, 160MPa, at low injection pressure of DME, 40㎫, the injector for DME needs larger diameters of nozzle holes and SAC volume at same energizing time. In addition to, the diameter of the orifice at the high pressure side should be increased to keep the minimum flow area ratio. As a result, diameter of nozzle holes and orifice were enlarged by 0.25㎜ and 1.0㎜, respectively. Also, to achieve the reliability an newly designed injector in DME, the solenoid sealing was changed in HNBR. Experimental results showed that the injection amount of the DME injector drastically increased by 191.9% comparison to that of diesel at 40㎫.
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(θs=60°, Ns=4, d/Dh=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.
CFD를 이용한 평형공을 가진 자동차 밀폐형 워터펌프의 축추력 특성에 대한 평가
이기수(Geesoo Lee),허형석(Hyungseok Heo),김현철(Hyunchul Kim),나병철(Byungchul Na),오창복(Changbok Oh) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
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 computed 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.
엔진 룸 해석을 이용한 프런트 엔드 모듈의 냉각 성능 평가
이기수(Geesoo Lee),허형석(Hyungseok Heo),원종필(Jongphil Won),김종철(Jongcheol Kim),권두혁(Duhyuk Kwon) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The objectives of this paper were to investigate the cooling performance of the newly developed front end module(FEM) for 2,000cc SUV by means of under-hood simulations at IDLE, 50 ㎞/h up-hill and 120 ㎞/h ; in particular, to analyze the effect of the additional designs eq., air guide or air duct in order to diminish reverse flows from engine room at IDLE condition. The proposed analysis has been performed by applying the commercial computational fluid dynamics(CFD) code, UH3D solver with heat exchanger and fan model, to the solution of the 3-D turbulent flow field on the under-hood flow field. UH3D represented fans as 3-D momentum sources defined by three source components and heat exchangers were treated as regions of momentum transfer and heat transfer. With regard to the newly developed FEM, it was shown that module feature with air guide was more effective in improving the cooling performance than it with air duct at lower cost, thanks to prevent heated recirculating flows from engine room at IDLE.
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.
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.
유압 비례제어 솔레노이드 밸브의 스풀형상이 응답특성에 미치는 영향
이기수(Geesoo Lee),김대현(Daehyun Kim),김현철(Hyunchul Kim),성형진(Hyungjin Sung),이현우(Hyunwoo Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
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 reliability of the employed analysis was demonstrated by the comparison between numerical results and experimental data. The modeling of the VFS valve and the notch depth of the delay parts of the spool was taken into account in analysis. The effects of varying the oil temperature on the pressure sensitivity curves and the seal leakage flow rates were investigated. The VFS valve was characterized by determining the variation in the equivalent orifice area (EOA)with the spool displacement. The pressure sensitivity curves were found to be precisely controlled by the relation between the depth and the area of the notch in the range of the characteristic length of the valve.