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OHV형 밸브트레인의 동특성 해석 및 최적 캠 형상 설계에 관한 연구
윤수환(S.H.Yoon),김도중(D.J.Kim),박병구(B.G.Park),신범식(B.S.Shin) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The objective of this study is to understand the dynamic characterictics of OHV type valve trains and to design optimal cam profile which will improve engine performance. A numerical model for valve train dynamics is presented, which aims at both accuracy and computational efficiency. The lumped mass model and distributed parameter model were used to describe the valve train dynamics. Nonlinear characterictics in the valve spring behavior were included in the model. Comprehensive experiments were carried out concerning the valve train dynamics, and the model was tuned based on the test results. The dynamic model was used in designing an optimal cam profile. Because the objective function has many local minima, a conventional local optimizer cannot be used to find an optimal solution. A modified adaptive random search method is successfully employed to solve the problem. Cam lobe area could be increased up to 7.3% without any penalties in kinematic and dynamic behaviors of the valve train.<br/>
강형민(H.M. Kang),조태환(T.H. Cho),김철완(C.W. Kim),윤수환(S.H. Yoon),권혁빈(H.B. Kwon),박춘수(C.S. Park) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
The aerodynamic performance of the pantograph of the next generation high speed train is analyzed. The calculation of the flow around pantograph is carried out by FLUENT; by the steady state flow calculation with κ-ω SST turbulence model, the lift force of the pantograph is computed. For the verification of the numerical schemes and grid systems, flow calculations are performed with the pantograph shape which was used at the experiments performed at Railway Technical Research Institute (RTRI) in Japan. Then, the difference of lift force between numerical and experimental results is about 10%. Therefore, selected numerical schemes and the current grid system is adequate for the analysis and prediction of the aerodynamic performance of pantograph system. Based on these numerical schemes and grid systems, the flow around a pantograph of the next generation high speed train is calculated and the lift force of the pantograph is predicted; the lift force of the pantograph is about 146N.
권혁빈(H.B. Kwon),윤수환(S.H. Yoon),남성원(S.W. Nam) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.5
The pressure transient inside the passenger cabin of high-speed train has been simulated using computational fluid dynamics(CFD) based on the axi-symmetric Navier-Stokes equation. The pressure change inside a train have been calculated using first order difference approximation based on a linear equation between the pressure change ratio inside a train and the pressure difference of inside and outside of the train. The numerical results have been assessed for the KTX train passing through a 9㎞ long tunnel of Wonju-Kangneung line at the speed of 250㎞/h assuming that the train is satisfying the train specification for airtightness required by the regulation.
커버 형상을 고려한 고속전철 팬터그래프 공력특성의 수치해석적 연구
강형민(H.M. Kang),김철완(C.W. Kim),조태환(T.H. Cho),김동하(D.H. Kim),윤수환(S.H. Yoon),권혁빈(H.B. Kwon) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.3
The aerodynamic performance of the pantograph on a high speed train was compared for different pantograph covers which are designed to block the aero-acoustic noise from the pantograph. For the study, two types of cover are designed: wedge and cone types. The lift force of pantograph with cover was compared with the force of pantograph only. The comparison clarified that the cone type cover increases the sideslip angle of the flow and decreases the lift force considerably. However, the wedge type cover changes the flow direction upward and increases the lift force of the pan head. This increment of lift force compensates the decrement of lift force caused by the blocking of the flow into the pantograph lower frame due to cover. Therefore, in case of the wedge type cover, the overall lift force changes slightly compared with the cone type cover.
강형민(H.M. Kang),김철완(C.W. Kim),조태환(T.H. Cho),김동하(D.H. Kim),윤수환(S.H. Yoon),권혁빈(H.B. Kwon) 한국전산유체공학회 2011 한국전산유체공학회 학술대회논문집 Vol.2011 No.11
The aero-acoustic analysis around a pantograph of a high speed train is performed. For the grid system, the real shape of the pantograph is utilized and FLUENT is used for the computation of the unsteady flow around the pantograph. Here, large eddy simulation (LES) model is applied for the calculation of the turbulence and aero-acoustic features of the pantograph are estimated by the Ffowcs Williams-Hawkings (FW-H) model. These numerical results are compared with those of experimental results; the aero-acoustic characteristics of the numerical analysis is similar to those of the experimental results and the difference of noise level is about 8dB(A).
3차원 형상을 고려한 고속철도에 의한 터널내 압력파 전파의 CFD 해석
신대용(D.Y. Shin),이상건(S.G. Lee),오현주(H.J. Oh),김홍근(H.G. Kim),윤수환(S.H. Yoon),김찬중(C.J. Kim) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.4
Research has importance in proposing the design of a tunnel with a vertical vent to secure passengers in a comfortable environment and safe against pressure. Using several analysis methods, the magnitude of the pressure induced by the vertical vent in the tunnel can be analyzed. In addition to the 3-dimensional method, the 2-dimensional method and the 2-dimensional axis-symmetric method are also used to analyze the strong and weak points of each so that the optimum analysis method can be obtained. As a result, it appears that the 2-dimensional axis-symmetric method is the most suitable in analyzing tunnel pressure consider to accuracy and time effective aspect. Also, the 3-dimensional method is disadvantageous in that it takes longer in calculating results, but is more effective in predicting phenomena around the vertical vent in the tunnel.