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Wind Pressure Transients in the Tunnel inside a Station Caused by a Passing High Speed Train
Nahmkeon Hur,Sa-Ryang Kim,Wook Kim,Sangyeul Lee 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.9
When a High Speed Train (HST) passes through a station with no stop, effects of wind pressure transients caused by this passing train have to be considered for the safety of passengers on the platform and for the possible structural safety problems as well. In Gwangmyeong and Daejeon stations of the Korean high speed railroad, tunnels inside stations for the passing train are proposed to reduce the noise and wind pressure transients to the passengers on the platform. In the present study, transient 3-D full Navier-Stokes solutions with moving mesh to implement train movement are obtained and compared with the results obtained by the towing tank experiment. Investigations on flow phenomena for various train speeds and design modifications are also performed.
허남건(Nahmkeon Hur),원찬식(Chan-Shik Won),유홍선(Hong-Sun Ryou),손기헌(Gihun Son),김사량(Sa Ryang Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
A general purpose CFD program NUFLEX has been developed, which is capable of analyzing laminar/turbulent flows in complex geometries with various physics models. The flow physics implemented in the program include internal tracking, cavitation, melting/solidification, spray, etc. In the present paper, a brief introduction of the program will go given and some application of the program will be demonstrated.
허남건(Nahmkeon Hur),김욱(Wook Kim) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.4 No.1
Drag reduction on vehicles are the main concern for the body shape designers in order to lower the fuel consumption rate and to aid the driving stability. The drag of bluff bodies like transportation vehicles is mostly pressure drag due to the flow separation, which can be minimized by controlling the location and size of the separation bubble. In the present study, the TURBO-3D code is incorporated with optimal algorithm based on analytical approximation method to obtain an optimal after body shape of the MIRA Model corresponding to the lowest drag coefficient. For this purpose three mutually independent afterbody angles are chosen as design variables, while the drag coefficient is chosen as an objective function. It is demonstrated in the present study that an optimal body shape having the lowest drag coefficient which is about 6% lower than that of the original shape has been successfully obtained within number of iterations of the optima] design loop.
허남건(Nahmkeon Hur),김성원(Seongwon Kim) 한국전산유체공학회 1999 한국전산유체공학회지 Vol.4 No.1
Spiral tube heat exchangers can find numerous applications in many engineering fields. Flow in spiral tubes is interest to engineers due to occurrence of secondary flow which enhances the cross-sectional mixing and the heat transfer rate. In the present study, an incompressible viscous 3-D flow in spiral tubes with rectangular cross-section of various torsion rate and Reynolds number is studied by using a finite volume method. It is shown that the axial velocity profile is affected by the secondary flow motion. Because there is some difference from correlation proposed by Hur et al, a lot of analysis and arrangement of experimental results are needed. This study showed the results of variation of hydrodynamic entry length for torsion and Re numbers.