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가솔린엔진의 흡기유량계수와 포트설계인자의 상관성에 관한 연구
이시훈(Sihun Lee),손진옥(Jin-Wook Son),곽영홍(Young-Hong Kwak),한봉훈(Bonghoon Han),김우태(Wootae Kim) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
An Intake Port of SI engines plays a key role on improving engine performance by maximizing full load volumetric efficiency or by optimizing in-cylinder air motion. However, designing an intake port has been usually performed based on port experts' experience and know-how, which means that analytical analyses are relatively insufficient. In this paper, port design parameters which decide an overall port shape were defined in order to correlate them relevantly with flow test results accumulated so far. This was expected to be one of the analytical approaches for future port development.<br/> Test species were composed of all twenty eight SI engines which cover major engine displacements from 1,000cc to 4,000cc. First, they were tested on a steady state flow test rig to find out their flow coefficients. Secondly, those flow coefficients were analyzed based on the port design parameters measured form the engines. The port design parameters were chosen to be measured easily in the real cylinder head, and then re-arranged to be non-dimensional<br/> parameters for further correlation analyses. The most effective parameters are valve height, valve head diameter, and the ratio of port size and cylinder bore diameter. The final correlation equation could predict flow coefficients within 2% deviation.
Ionization Probe를 이용한 S.I.엔진의 Knock 발생 부위 측정
이시훈(Sihun Lee),이수룡(Suryong Lee),이경환(Kyung-Hwan Lee) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_2
The knock in a spark ignition engine has been investigated for many years to avoid the damage to the engine and unpleasant feeling caused by the pressure waves propagating across the combustion chamber. In this research. knock intensity and knock onset angle were defined as a peak to peak value of the band pass filtered combustion pressure and the crank angle at which this signal exceeded the threshold on each cycle. The determination of DBL was investigated with the standard deviation of knock intensity and the location of autoignition was examined by ionization probes in the gasket region in a four valve single cylinder engine which was modified to install the pressure transducer and 8 ionization probes in the specially designed PCB (Printed Circuit Board) cylinder head gasket.<br/>
우주 발사체의 포고현상 예측을 위한 공급/추진계의 파이프 압력모드 해석 기법 제안
이상구(SangGu Lee),이시훈(SiHun Lee),신상준(SangJoon Shin) 한국추진공학회 2017 한국추진공학회 학술대회논문집 Vol.2017 No.5
액체 추진제를 사용하는 우주발사체의 설계 단계에서 고려되는 사항 중 축방향 동적 불안정성인 포고현상에 관한 연구를 진행하였다. 포고 현상이란 발사체 구조계의 축방향 진동이 공급/추진계의 압력 및 유량의 변화를 유발하고, 이러한 변화가 구조계를 다시 가진하는 닫힌계를 구성하여 발사체의 진동을 점차적으로 증가시키는 불안정성을 말한다. 본 논문에서는 포고 현상 중 발사체 공급/추진계에서 발생하는 압력 및 유량의 변화에 대한 동적해석에 초점을 맞추었다. 우주왕복선의 연구사례를 바탕으로 공급/추진계의 음향모드 해석을 수행하여 구조계의 불안정성을 유발하는 공급라인의 모드를 예측하고자 하였다. Among the factors considered in the design stage of a space launch vehicle using liquid propellant, research has been focused out on the pogo phenomenon, longitudinal dynamic instability. The pogo phenomenon refers to the instability that the longitudinal vibration of the launch vehicle structure causes a change in the pressure and flow rate of the fluids in propulsion system, and this change re-excites the fuselage structure. This mechanism constitutes a closed system to gradually increase the vibration of the launch vehicle. This paper specifically focuses on the dynamic analysis of pressure and flow changes in the propulsion system. Based on the example study of the space shuttle, the acoustic modal analysis of the propulsion system is performed to predict the modes of the supply line causing instability of the fuselage.