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압축천연가스(CNG)용 고압분사 인젝터의 노즐 주위 3차원 충격파 거동 분석
문성준(Seong-Joon Moon),정수진(Soo-Jin Jeong) 한국자동차공학회 2020 한국자동차공학회 지부 학술대회 논문집 Vol.2020 No.6
To improve the air fuel ratio of in-cylinder of manifold port injection for CNG engine, the gaseous fuel should be injected at high pressure gas injector, which allows for sufficient fuel supply and good mixture formation in the cylinder. Nozzle design of the CNG injector are regarded as a critical design factor because they have a direct influence on the amount of fuel supply into cylinder and the jet characteristics around nozzle-exit of CNG injector. In this study to examine the design variables of nozzle tip by using DES based on Eulerian approach. In addition, the analysis results were verified by comparison of penetration length with test result of Schlieren and previous literature [4]. Our computational result is in a good agreement with the experimental results within an accuracy of less than 4.8%. Additionally, this study investigated the effect of size increase of nozzle tip on mass fraction rate by comparing two different phase fuels which the one is gaseous fuel and the other liquid fuel. As a result, when the nozzle-exit size is increased 5 times, the injection rate of liquid fuel is increased 10 times, but the injection rate of gaseous fuel is increased by 1.8 times. On the other hand, the inner stepped nozzle tip show much more strong inhibition effect on occurring mach-disk shock, resulting in good mixture formation even at higher injection pressure of 1.78 times comparing with of flated nozzle tip.
천연가스의 고압 간접 분사에 따른 과소 팽창 제트의 충격파 구조와 천이 거동에 관한 수치적 연구
문성준(Seong-Joon Moon),정수진(Soo-Jin Jeong) 한국자동차공학회 2020 한국 자동차공학회논문집 Vol.28 No.4
To maximize the combustion efficiency of manifold port injection for the CNG(compressed natural gas) engine, the gaseous fuel should be injected at a high pressure using a gas injector, which allows for sufficient fuel supply and good mixture formation in the cylinder. In particular, the increase of the NPR(nozzle pressure ratio) because of the high-pressure injection causes shockwave formation near the nozzle exit as well as a change in the shock patterns in the gas jet. The characteristics of gas jets are regarded as a key design factor because they have a direct influence on the amount of fuel supply into the cylinder and on the mixture formation around the nozzle exit of the gas injector. The experiments for investigating the characteristics of shockwaves, however, are very expensive and time-consuming. Therefore, a three-dimensional numerical model was developed in this study to examine the characteristics of shockwave structures and the change in the shock of the underexpanded gas jet for various injection conditions, using DES(detached eddy simulation) based on the Eulerian approach. In addition, the analysis results were verified by comparing the penetration length with the test results of the previous studies [10]. The obtained computation result is in good agreement with the experimental value, with a less than 5 % difference. It can be found that the normal pattern of repeated barrel shockwaves, the regular reflection pattern with reflection shock added, and the Mach disk pattern with Mach disk shock, are successively generated as the NPR increases. Additionally, this study investigated the effect of geometrical modification on the shock structure by comparing two different geometries: a flattened nozzle exit and an inner-stepped nozzle exit. For the results, Mach disks started to emerge over an NPR of 3.37 in the case of the flattened nozzle exit. On the other hand, in the case of the inner-stepped nozzle exit, Mach disks began to occur when the NPR was over 6. The study results show that the inner-stepped nozzle exit has a much stronger Mach disk inhibition effect, resulting in good mixture formation even at higher NPR conditions compared with the flattened nozzle exit.
신준수(Joon Su Shin),김경순(Kyoung Soon Kim),강경환(Kyoung Hwan Kang),문성준(Seong Joon Moon),이우영(Woo Young Lee),김박광(Bak kwang Kim) 대한약학회 1996 약학회지 Vol.40 No.3
To investigate the antialopecic effect of N-4-salicylomide-2-amino-6-piperidinopyrimidine 3-oxide(SALMI) and its salt on the hair of black mouse (C57BL/6), this study was carried out. When salmi and its salt in ethanol solution were administered to the black mouse (C57BL/6) by route of skin, both of them promoted the growth of hair.
승용차량용 Urea-SCR 시스템 분무 특성에 관한 연구
박광진(Kwang-Jin Park),문성준(Seong-Joon Moon),정수진(Soo-Jin Jeong),오세두(Se-Doo Oh),박성영(Sung-Young Park),서지훈(Jee-Hoon Seo) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
TIER II and EURO-5/6 legislation require a high conversion level for nitrogen oxides to meet the emission levels for diesel engine. Diesel engines are difficult to simultaneously meet nitrogen oxides and particulate matter standards, because NOx and PM have the relation of trade-off in the diesel engine. The Urea-SCR system is a promising device to reduce NOx emissions. In condition of high catalyst temperature, over 90% NOx conversion efficiency is indicated. The key factor to implementation of SCR technology on an automobile is fast thermolysis, uniformity of ammonia and gas, and reducing ammonia slip. This paper investigate the spray characteristics of a urea injector, such as the spray angle, injection quantity, penetration length and SMD. Also Urea-SCR system has been examined in detail under various injection pressures.