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허신(S. Hur),박찬경(C. K. Park),하성도(S. D. Ha),한형석(H. S. Han) 한국철도학회 1998 한국철도학회 학술발표대회논문집 Vol.- No.-
light rail vehicle is modeled as a 2 d. o. f linear system for the design of vertical suspension characteristics and a 4 d.o. f linear system for the design of lateral suspension characteristics. FRA"s class-5-track irregularity is used for the exciting disturbance on track. Suspension stiffness and damping is selected on the basis of the ride quality and suspension stroke trade-off for the bogie of light rail vehicle. The optimum value of primary and secondary suspension characteristics is determined. And the stability of full vehicle model for the LRV is analyzed using the VAMPIRE program and critical speed is determined.
강동민(D. M. Kang),정영래(Y. R. Jung),박원규(W. G. Park),하성도(S. D. Ha) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.4 No.3
This paper describes the flow field analysis of an automobile with crosswind effects of 15˚, 30˚, 45˚ and 60˚ of yaw angles. The governing equations of the 3-D incompressible Navier-Stokes equations are solved by the iterative time marching scheme. The Chimera grid technique has been applied to efficiently simulate the flow around the side-view mirror. The computated surface pressure coefficients have been compared with experimental results and a good agreement has been achieved. The A- and C-pillar vortex and other flow phenomena around the ground vehicle are evidently shown. The variation of aerodynamic coefficients of drag. lift. side force and moments with respect to yaw angle is systematically studied.
강동민(D. M. Kang),정영래(Y. R. Jung),박원규(W. G. Park),하성도(S. D. Ha) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.4 No.3
This paper describes the flow field analysis of an automobile with crosswind effects of 15˚, 30˚, 45˚ and 60˚ of yaw angles. The governing equations of the 3-D incompressible Navier-Stokes equations are solved by the iterative time marching scheme. The Chimera grid technique has been applied to efficiently simulate the flow around the side-view mirror. The computated surface pressure coefficients have been compared with experimental results and a good agreement has been achieved. The A- and C-pillar vortex and other flow phenomena around the ground vehicle are evidently shown. The variation of aerodynamic coefficients of drag. lift. side force and moments with respect to yaw angle is systematically studied.
박영준(Y.J. Park),박원규(W.G. Park),하성도(S.D. Ha) 한국전산유체공학회 1997 한국전산유체공학회 학술대회논문집 Vol.1997 No.-
Two-dimensional unsteady compressible Navier-Stokes equation solver has been applied to solve the flow around the high seed train entering into the tunnel. The numerical scheme of AF+ADI was used to effidently solve Navier-stokes equations in the curvilinear coordinate system. The sliding multiblock technique was implemented to handle the relative motion of the moving train and the stationary tunnel. A H-type Multi-blocked structure grid and elliptic method is used to obtain the minimum computation error. From the present simulation, the compression wave was observed in front of the train in the form of almost a plane wave. The high pressure in the gap between the upper surface of the train and the tummel wall was also found due to the blockage effects. History of the tunnel wall-pressure distribltions and the aerodynamic forces action on the trains are discussed.
측풍영향을 고려한 고속전철 주위의 3차원 난류유동 해석
정영래(Y. R. Jung),박원규(W. G. Park),하성도(S. D. Ha) 한국전산유체공학회 1996 한국전산유체공학회지 Vol.1 No.1
An iterative time marching procedure for solving incompressible turbulent flow has been applied to the flows around a high speed train including cross-wind effects. This procedure solves three-dimensional unsteady incompressible Reynolds-averaged Navier-Stokes equations on a non-orthogonal curvilinear coordinate system using first-order accurate schemes for the time derivatives and third/second-order accurate schemes for the spatial derivatives. Turbulent flows have been modeled by Baldwin-Lomax turbulent model. To validate present procedure, the flow around a high speed train at zero yaw angle was simulated and compared with experimental data. Generally good agreement with experiments was achieved. The flow fields around the high speed train at 9.2˚. 16.7˚ and 45˚ of yaw angle were also simulated.
측풍영향을 고려한 고속전철 주위의 비압축성 점성 유동 해석
정영래(Y.R. Jung),박원규(W.G. Park),김홍원(H.W. Kim),하성도(S.D. Ha) 한국전산유체공학회 1995 한국전산유체공학회 학술대회논문집 Vol.1995 No.-
The flow field around a high-speed train including cross-wind effects has been simulated. This study solves 3-D unsteady incompressible Navier-Stokes equations in the inertial frame using the iterative time marching scheme. The governing equations are <br/> differenced with 1st-order accurate backward difference scheme for the time derivatives. 3th-order accurate QUICk scheme for the convective terms and 2nd-order accurate central difference scheme for the viscous terms. The Marker-and-Cell concept was applied to efficiently solve continuity equation. which is differenced with 2nd-order accurate central difference scheme. The 4th-order artificial damping is added to the continuity equation for numerical stability. A C-H type of elliptic grid system is generated around a high-speed train including ground. The Baldwin-Lomax turbulent model was implemented to simulate the turbulent flows. To validate the present procedure, the flow around a high speed train at constant yaw angle of 45°and 90°has been simulated. The simulation shows 3-D vortex generation in the lee corner. The flow separation is also observed around the rear of the train. It has concluded that the results of present study properly agree with physical flow phenomena.