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밸브 닫힘각 변화에 따른 버터플라이밸브의 손실계수 평가
이지근(Jeekeun Lee),노병준(Byungjoon Rho),최희주(Heejoo Choi) 한국항공우주학회 2008 韓國航空宇宙學會誌 Vol.36 No.1
밸브 디스크 직경이 25.4 ㎜ 인 소형 버터플라이밸브의 유동특성이 다양한 밸브 닫힘각에 대해 실험적으로 연구되었다. 밸브 디스크각이 작은 경우 유량조절특성을 향상시키기 위해 주어지는 밸브 닫힘각을 0°, 5°, 10°, 20°, 30°로 변화시켜 밸브 디스크각에 따른 손실계수를 측정하였다. 또한 밸브선단 형상이 손실계수 변화에 미치는 영향을 조사하였다. 밸브 닫힘각이 증가함에 따라 최대손실계수는 감소하며, 밸브 닫힘각 0°~5°에서 가장 큰 감소를 나타냄을 알 수 있었다. 밸브 디스크 형상에 따른 손실계수는 밸브 닫힘각이 0°인 경우 날카로운 모서리를 갖는 디스크가 더 큰 손실계수를 나타낸 반면, 닫힘각 10°의 경우 날카로운 모서리를 갖는 디스크의 경우가 더 낮은 손실계수를 나타냄을 알 수 있었다. In this study, flow characteristics of a small-sized butterfly valve with the valve disk diameter of 25.4 ㎜ have been investigated experimentally for the valve closed angles. In order to examine the flow characteristics of the butterfly valve, loss coefficient (K<SUB>v</SUB>) was obtained at the valve closed angles of 0°, 5°, 10°, 20° and 30°. In addition, the effects of the valve disk edge shape were examined. As the result of the experiment, the maximum loss coefficient (K<SUB>vmax</SUB>) was decreased with the increase of the valve closed angle, and it had the maximum decrease ratio at the valve disk angles of 0°~5°. The valve disk edge shape have an effect on the loss coefficient of the valve around the small valve closed angle.
스마트무인기 연료시스템 연료이송 제트펌프의 성능평가에 관한 실험적 연구
이윤권(Yoonkwon Lee),김의수(Euisoo Kim),박설혜(Sulhye Park),이지근(Jeekeun Lee),이창호(Changho Lee),이수철(Soochul Lee),최희주(Heejoo Choi) 한국항공우주학회 2007 韓國航空宇宙學會誌 Vol.35 No.12
스마트무인기 연료공급시스템에 사용되는 제트펌프의 연료탱크 사이의 연료이송 특성이 실험적으로 조사되었다. 제트펌프의 작동조건은 비행체의 임무에 따른 엔진의 요구사항을 만족하도록 설정되었으며, 주어진 조건에서 제트펌프의 성능을 평가하였다. 제트펌프의 유량비 변화에 따른 압력비 및 효율이 측정되었으며 면적비 변화 등이 고려되었다. 평가 결과로부터 제트펌프는 주어진 압력비보다 큰 범위에서 작동목표인 유량비 2.23을 만족하였다. 효율보다 연료공급량이 중시되는 연료이송 제트펌프의 경우 면적비 변화를 통하여 허용 압력비 범위 내에서 유량비 조절이 가능함을 알 수 있었다. The fuel transfer characteristics of the jet pump between fuel tanks, which is applied in the smart UAV fuel supply system, were experimentally investigated. The operating conditions of the jet pump were setup to meet the engine requirement according to mission profile, and the jet pump performance was evaluated at those conditions. The pressure ratio and the efficiency of the jet pump were measured with the variation of flow ratio. In addition, the area ratio was taken into the consideration to examine the effect on the jet pump performance. From the evaluation results, the jet pump met the fundamental requirement to transfer fuel with the flow ratio of 2.23. In the case of the jet pump that is focused on the fuel transfer quantity rather than its efficiency, the flow ratio would be adjusted through the variation of area ratio of the jet pump within the permitted limit of pressure ratio.
스마트무인기 연료계통 제트펌프의 내부 유동 특성에 관한 실험적 연구
이윤권(Yoonkwon Lee),이지근(Jeekeun Lee),이창호(Changho Lee),최희주(Heejoo Choi) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.2
The jet pumps are widely used to transfer the fuel between the tanks in an aircraft fuel supply system. However detailed design procedures for determining the size of components of the jet pumps are not known so well. In this paper, the flow characteristics of the jet pump, which is applied in the fuel transfer system for the smart UAV (Unmanned Aerial Vehicle), were experimentally investigated using the acrylic jet pump model for the visualization of the internal flow. The pressure distributions within the jet pump were measured, and then the loss coefficients of each part were calculated. The effects of Reynolds number and the distances (S) between the exit of the primary nozzle and the mixing chamber entrance were investigated. In addition, cavitation phenomena were considered through the flow visualization inside the jet pump. As a conclusion from the experiment, the contraction shape of the primary nozzle has a strong effect on the loss coefficient of the nozzle and the cavitation occurrence. Cavitation starts around the nozzle exit, and then it propagates to the full flow fields of the jet pump.
스마트 무인기 연료계통 제트펌프 설계 및 성능예측에 관한 연구
이윤권(Yoonkwon Lee),박설혜(Sulhye Park),이지근(Jeekeun Lee),이창호(Changho Lee),최희주(Heeju Choi),이수철(Soochul Lee),정재헌(Jeahun Jeong) 한국자동차공학회 2007 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
This paper is concerned with the design and performance prediction of jet pumps for fuel system. The jet pump is important component to transfer the fuel between tanks in fuel supply system. However detailed design procedures for sizing the component of the jet pumps are known a little. In this paper the jet pump was designed according to the design procedure based on the theoretical analysis. For verifying the design results from the theoretical approach, the performance of the designed jet pump was predicted using a commercial analysis code and was verified through the experiment for the jet pump sizing with high performance. The flow ratio and pressure ratio were compared with target value and satisfied the demands in fuel supply system. Further research was carried out to obtain more conclusive information from various interference conditions and for improvement in performance.
스마트무인기연료공급시스템 연료이송 제트펌프의 설계 및 성능해석에 관한 연구
박설혜(Sulhye Park),이윤권(Yoonkwon Lee),이지근(Jeekeun Lee),이창호(Changho Lee),이수철(Soochul Lee),최희주(Heejoo Choi) 한국항공우주학회 2007 韓國航空宇宙學會誌 Vol.35 No.11
스마트무인기 연료공급시스템에 사용되는 연료이송 제트펌프의 1차원 유동해석을 통한 설계가 이루어졌으며 성능 검증 및 설계 개선점을 찾고자 상용코드를 이용하여 전산해석이 수행되었다. 해석적 연구 결과로부터 제트펌프는 스마트무인기 연료공급시스템에서 요구하는 유량비 2.23을 만족하는 설계가 이루어졌음이 확인되었다. 구동노즐에 작용하는 압력은 낮게 예측된 손실계수로 인하여 전산해석의 경우가 1차원 유동해석을 통한 설계값보다 더 높은 값을 나타냈다. 결과적으로 제트펌프 구성 요소의 정확한 크기 결정을 위해서는 각 주요부에서의 손실계수에 대한 정확한 데이터가 필요하며, 데이터는 측정위치 및 측정대상의 기하학적 형상 정보와 함께 제공되어져야 한다. Design and performance analysis of the jet pump to transfer fuel between tanks in the smart UAV fuel supply system were carried out through one dimensional flow analysis and the flow analysis using a commercial CFD code. From the analysis results, it was proved that the jet pump was designed with the flow ratio of 2.23 that is the fundamental requirement of the jet pump design. The comparison results showed that the primary nozzle pressure is higher in the CFD analysis than in one dimensional flow analysis, mainly due to the underestimated loss coefficient of the primary nozzles. Consequently, the loss coefficients of the jet pump components should be determined more precisely for the design of the jet pumps with high performance.
Effect of Reynolds Numbers on Counter-rotating Swirling Flow in a Model Gas Turbine Combustor
Sangho Lee(이상호),Yuin Jin(진유인),Gyongwon Ryu(유경원),Jeekeun Lee(이지근) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
The characteristics of swirling flow in a model gas turbine combustor, which is one of the most important phenomenon for efficiency and flame stabilization in gas turbines, were studied in the paper. The gas turbine combustor was modeled as rectangular shape to examine the swirling flow generated by swirler for the experiment. The model combustor consists of counter-rotating axial swirler to generate the swirling flow. A PIV system was used to measure velocity components of the swirling flow. Additionally, the mean and turbulent components were discussed which were calculated by averaging the acquired many seeding particle images. The pure water was used as a working fluid. The characteristics of swirling flow, including the formation of a central recirculation zone, corner vortex, and the wall flow along the model combustor wall, were mainly discussed and investigated with Reynolds numbers.
Urea-SCR 머플러 다공튜브 형상변화에 따른 유동특성 해석
이상규(Sangkyoo Lee),문남수(Namsoo Moon),이지근(Jeekeun Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
This study reports a numerical analysis of the flow characteristics of the Urea-SCR muffler system with the various geometry of the perforated tube. The perforated tube set inside the muffler is generally used to disperse uniformly the Urea-water solution spray and to increase the reaction inside the SCR catalyst, resulting in the reduction of NOx. The steady flow model was simulated with the general-purpose software package "FLUENT", to study the flow characteristics in the muffler. As the working fluid the air at the room temperature was used, instead of the exhaust gas and Urea-water solution spray mixture. The effects of the hole diameter and the blockage ratio on the flow characteristics were investigated for optimal muffler system design that is attained to produce the uniform velocity or pressure distributions in the front of the SCR catalyst. From the analysis results, it was clarified that the flow characteristics inside the muffler are very sensitive to the perforated tube geometry and significantly affected by the blockage ratio.
Urea-SCR 시스템 Urea-Salt 퇴적방지를 위한 믹서하우징 형상변화에 따른 유동제어에 관한 연구
이방욱(Banguk Lee),이지근(Jeekeun Lee) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
The Urea-SCR system commercialized shows a remarkable performance to reduce NOx emission in heavy duty diesel engines. However, Urea-water solution injected upstream a mixer, which is set up inside a exhaust pipe to promote exhaust gas-atomized droplet mixing, bumps up against the wall of a exhaust pipe as the droplets flowing downstream through the exhaust gas. The urea deposited on the wall of the exhaust pipe is changed into the Urea-salt, resulting in the decreased life-time of the SCR catalysts and the increased exhaust emission. For this reason, the development of the urea deposition avoidance technologies is being treated as an important issue of the Urea-SCR system. Analytical study was carried out to investigate the effects of the flow characteristics around the mixer with the variation of the mixer housing surrounding and supporting the mixer, which is designed to increase the wall flow and then to reduce droplet deposition. The flow characteristics was simulated by applying for K-e RNG model, and the vane angles and the position of the mixer were changed : Angle of 0°, 1°, 2°, 3°, and Mixer positions of 0Lh, 0.5Lh, 1Lh. Analytical results were verified by the experimental results using a Hot-wire anemometer system. The wall flow onto the exhaust pipe was improved with changing the angle of the mixer housing, and the wall flow improved more when the position of the mixer was on 0Lh.