터널을 통과하는 열차의 객실 내 압력 변동 해석

권혁빈(H.B. Kwon),윤수환(S.H. Yun),남성원(S.W. Nam) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.1

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 9km long tunnel of Wonju-Kangneung line at the speed of 250km/h assuming that the train is satisfying the train specification for airtightness required by the regulation.

터널을 통과하는 열차의 객실 내 압력 변동 해석

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.

전산유체역학을 이용한 고속열차 공기저항 평가

권혁빈(H.B. Kwon),김영남(Y.N. Kim) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11

A series of aerodynamic studies have been conducted to assess and reduce the aerodynamic drag of the HEMU-430X train, the next generation high-speed train with maximum speed of 430km/h including Computational Fluid Dynamics based on 3-dimensional Navier-Stokes equation. Various meshes and numerical methods have been tested to find best way to predict aerodynamic drag of high-speed train. The numerical solutions have been compared with wind tunnel measurements and validated. In addition, Reynolds number effect and moving ground effect have been investigated which can easily be applied to numerical analysis. The contributions of pressure drag and skin friction drag at each cars have been analyzed to assess the composition of aerodynamic drag quantitatively.

승객 이명감 기준을 만족하는 고속철도 터널 최소 단면적에 대한 연구

권혁빈(H.B. Kwon) 한국전산유체공학회 2015 한국전산유체공학회지 Vol.20 No.3

Pressure change inside cabin as well as in tunnel has been calculated to assess the passenger pressure comfort of high-speed train. C-STA<SUP>TM</SUP> , a CFD program based on axi-symmetric Navier-Stokes equation and Roes FDS has been used to simulate the pressure change in tunnel during a high-speed train passing through it. To present the relative motion between the train and the tunnel, a modified patched grid scheme based on the structured grid system has been employed. The simulation program has been validated by comparing the simulation results with field measurements. Extensive parametric study has been conducted for various train speed, tunnel cross-sectional area and tunnel length to the pressure change in cabin. KTX-Sancheon(KTX2) high-speed train has been chosen for simulation and the train speed have been varied from 200 km/h to 375 km/h. The tunnel length has been varied from 300 m to 7.5 km and tunnel area from 50 m<SUP>2</SUP> to 120 m<SUP>2</SUP>. Total 504 simulations have been conducted varying the parameters. Based on the database produced from the parametric simulations, minimum tunnel cross-sectional area has been surveyed for various train speeds based on Korean regulation on pressure change in cabin.

압축기 적용 고속열차의 터널 통과 시 공기력 저감 효과 연구

박희범(H.B. Park),김영매(Y.M. Jin),권혁빈(H.B. Kwon),이웅현(W.H. Lee) 한국전산유체공학회 2020 한국전산유체공학회지 Vol.25 No.1

A series of CFD simulation have been conducted to evaluate the effect of the Hyperloop-type compressor adapted to a high-speed train to reduce the aerodynamic drag, the pressure transient and the micro-pressure during tunnel passage. Unsteady axi-symmetric Navier-Stokes equation has been employed to calculate the unsteady flow field induced by the KTX-Shancheon train through the Honam high-speed line tunnel. By comparing the calculation results with and without compressor, the effect of compressor to the reduction of tunnel transient forces has been analyzed. It is concluded that the adaption of compressor of 30% inlet area relative to the train cross-sectional area reduces the mean aerodynamic drag to 15.9%, the pressure change in the cabin up to 24.9%, and the micro-pressure wave to 40.3%.

차세대 고속철도 판토그래프의 공력특성 해석

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.

고속 열차의 터널 교행에 따른 팬터그래프의 접촉력 안정성 평가

강형민(H.M. Kang),권혁빈(H.B. Kwon) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.1

The stability of the contact force of CX pantograph was analyzed when HEMU-430Xs, the next generation high speed trains, were crossed in Tunnel. For this, three dimensional unsteady flow simulations were performed during the HEMU-430Xs’ crossing in Honam tunnel with the speeds of 250 km/h and 400 km/h. Then, relative flow velocity fluctuation was computed in front of the pantograph and the standard deviation of the contact force of CX pantograph was obtained according to the train’s velocity. It was confirmed that trains’ crossing in tunnel originated the frequent velocity fluctuation into the pantograph; in X-t diagram, the compression and expansion waves from crossing trains were propagated inside the tunnel and caused the frequent pressure fluctuation near the train. They accelerated or decelerated the flow velocity into the pantograph. Then, the velocity exceeded the speed limit of CX pantograph for stable contact of the pantograph and catenary system when the train velocity was 400 km/h; the train’s velocity should be lowered below 400 km/h when the trains were crossed in the tunnel.

전산유체역학을 이용한 지하터널을 주행하는 다수 차량의 공기저항에 관한 연구

김부선(B.S. Kim),박희범(H.B. Park),김영매(Y.M. Jin),권혁빈(H.B. Kwon) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.1

In order to analyze effects of various parameters on aerodynamic drag of an underground freight system and to suggest a plan for reducing aerodynamic drag, a three-dimensional simulation using computational fluid dynamics has been made and aerodynamic drags respectively for a single vehicle running and a platooning in which a group of two or more aligned vehicles run have been calculated. A concept design of an underground freight system has been made to obtain two concept designs, i.e., a pallet-exclusive transportation design and a vehicle-compatible transportation design. ANSYS FluentTM has been used for modeling, meshing and numerical analysis for respective designs. It can be known from the analysis that aerodynamic drag significantly increases in an underground tube compared to an open space and the amount of an increase of aerodynamic drag is considerably affected by the sectional area ratio between the tube and the capsule. In addition, the aerodynamic drag in the platooning is reduced by up to 10% compared to the single running depending on the number of the capsules and the distance between the capsules.

HEMU-430X 열차 터널 주행 시 CX 팬터그래프의 접촉력 안정성 평가

강형민(H.M. Kang),권혁빈(H.B. Kwon) 한국전산유체공학회 2018 한국전산유체공학회지 Vol.23 No.1

The stability of the contact force of CX pantograph was assessed when HEMU-430X, the next generation high speed train, was running in Tunnel. For this, three dimensional unsteady flow simulations were performed during the HEMU-430X’s running in Kyung-Bu tunnel with the speeds of 250㎞/h and 400㎞/h. From the calculations, flow velocity fluctuation in front of the pantograph was calculated according to the train velocity. Then, the stability of the contact force of CX Pantograph was assessed according to the train’s velocity based on the standard deviation of the contact force of CX pantograph. From the analyses, it was confirmed that the compression wave to tunnel exit or expansion wave to tunnel entrance decelerated the air velocity into pantograph, which enhanced the stability of contact between CX pantograph and catenary system. Concerning the train velocity, if the train’s velocity was 400㎞/h, the CX pantograph were statistically deviated from the catenary system in most of the tunnels; the train’s velocity should be lowered below 400㎞/h for stable contact of CX pantograph and catenary system.

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.