• 한국전산유체공학회지
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• 제20권3호
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• pp.62-69
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• 2015

Pressure change inside cabin as well as in tunnel has been calculated to assess the passenger pressure comfort of high-speed train. $C-STA^{TM}$, a CFD program based on axi-symmetric Navier-Stokes equation and Roe's 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 $50m^2$ to $120m^2$. 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.

• 한국유체기계학회 논문집
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• 제17권5호
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• pp.54-59
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• 2014

The new high speed combi train prototype project was developed which named HSB. It runs over the speed of 330km/h. As the speed of the train exceeds over 300km/h, due to pressure change in tunnel, aerodynamic problems such as sudden drag increase, severe acoustic noise, passenger discomfort and tunnel pressure sonic boom were occurred. This aerodynamic characteristics in tunnel should be reviewed in early design state to enhance the performance and driving quality of new high speed train. In this paper, the aerodynamic characteristics in tunnel for HSB such as pressure waves in tunnel, a rate of pressure change in cabin and micro pressure wave that cause sonic boom outside tunnel are analyzed by 2D axisymmetric CFD simulations. The results are also compared with the value for ordinary high speed train like the KTX-Sancheon. It is helpful how to design the configuration of HSB train. Finally it shows that the HSB train was well designed in tunnel condition because all values fulfill the criterions on UIC code and Korean national regulations.

• 소음진동
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• 제7권6호
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• pp.959-966
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• 1997

In general, the booming noise intensity at tunnel exit is strongly related to the gradient of the compression wave front created by high speed train entering the tunnel. This paper presents some results in relation with the compression wave front produced when the high speed train enters a tunnel. Four kinds of tunnel entrance shape with real dimensions were studied to investigate the formation of compression wave front inside tunnel by train entering tunnel. Computations were carried out using three-dimensional compressible Euler equation with vanishing viscosity and conductivity of fluid. According to the results, the flow disturbances occured at tunnel entrance were eliminated by tunnel hood with same cross sectional area. The compression wave front is formed completely at 30-40m from tunnel entrance. The maximum pressure gradient of compression wave front is reduced by 29.8% for the inclined tunnel hood and reduced by 21.5% for the tunnel hood with holes at the top face with tunnel without hood. The length of the inclined hood is 15m and the length of the hood with holes is 20m.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.627-635
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• 1997

In general, the booming noise intensity at tunnel exit is strongly related to the gradient of the compression wave front created by high speed train entering the tunnel. This paper presents some results in relation with the compression wave front produced when the high speed train enters a tunnel. Four kinds of tunnel entrance shape with real dimensions were studied to investigate the formation of compression wave front inside tunnel by train entering tunnel. Computations were carried out using three-dimensional compressible Euler equation with vanishing viscosity and conductivity of fluid. According to the reslts, the flow disturbance occured at tunnel entrance were eliminated by tunnel hood with same cross sectional area. The compression wave front is formed completely at 30-40m from tunnel entrance. The maximum pressure gradient of compression wave front is reduced by 29.8% for the inclined tunnel hood and reduced by 21.5% for the tunnel hood with holes at the top face with tunnel without hood. The length of the inclined hood is 15m and the length of the hood with holes is 20m.

• 한국작물학회지
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• 제31권1호
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• pp.84-90
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• 1986

단옥수수 품종 Great Bell을 3월 5일, 15일, 25일과 4월 4일에 파종하고, 파종기마다 투명 P.E. 필름의 Tunnel, Tunnel slit 및 Mulch가 기온, 지온 및 단옥수수의 생육과 수량에 미치는 영향은 다음과 같다. 1. 최고최저기온과 최고최저지온 모두 Tunnel>Tunnel slit> Mulch의 순으로 높았으며 P.E. 필름 처리간 온도차이는 최고기온 및 지온은 컸으나 최저기온 및 지온은 적었다. 2. 4월 하경에 Tunnel내 기온이 4$0^{\circ}C$가 넘어 필름을 열면 Tunnel구의 기온은 Mulch에서와 같으나 지온은 낮았다. Tunnel slit는 필름을 열지 않고 slit수를 증가시켜 고온장해를 피할 수 있었다. 3. 옥수수 유묘기의 저온피해는 Mulch에서는 지상부가 고사하였으나 재생되었고, Tunnel slit에서는 잎의 일부가 피해를 입었으나 Tunnel에서는 피해가없었다. 4. 3월 5일 및 15일 파종에서 Tunnel은 Tunnel slit나 Mulch보다 초기생육과 출사를 촉진시켰으나 고온으로 낮에 필름을 열었던 3월 25일 및 4월 4일 파종에서는 오히 려 지연시켰다. 5. 파종이 늦을수록 파종에서 출사까지 일수가 단축되어 3월 25일 파종에 비하여 3월 5일 및 15일 파종은 출사가 2~3일 빨랐으며 4월 4일 파종은 6~9일 늦었다. 6. 적조위축병은 한기파종에서 이병율이 높았으며, 3월 25 일 및 4월 4 일 파종의 Tunnel slit에서는 생육초기에 필름을 열지 않아 적조위축병 이병율이 Tunnel 이나 Mulch보다 낮았다. 7. 상품성 있는 웅수수는 적조위축병이 심했던 3월 5일 파종의 Mulch를 제외하면 모든 처리간에 차이가 없었다. 조수입은 상품가치가 큰 웅수가 많았던 3월 25일 파종의 Tunnel 및 Tunnel slit와 가격이 높고 웅수가 많았던 3월 5 일 파종의 Tunnel과 Tunnel slit에서 높았다.

• Wind and Structures
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• 제28권4호
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• pp.203-213
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• 2019

The topography and geomorphology are complex and changeable in western China, so the railway transition section is common. To investigate the aerodynamic effect of the subgrade-tunnel transition section, including a cutting-tunnel transition section, an embankment-tunnel transition section and two typical scenarios for rail infrastructures, is selected as research objects. In this paper, models of standard cutting, embankment and CRH2 high-speed train with the scale of 1:20 were established in wind tunnel tests. The wind speed profiles above the railway and the aerodynamic forces of the vehicles at different positions along the railway were measured by using Cobra probe and dynamometric balance respectively. The test results show: The influence range of cutting-tunnel transition section is larger than that of the embankment-tunnel transition section, and the maximum impact height exceeds 320mm (corresponding to 6.4m in full scale). The wind speed profile at the railway junction is greatly affected by the tunnel. Under the condition of the double track, the side force coefficient on the leeward side is negative. For embankment-tunnel transition section, the lift force coefficient of the vehicle is positive which is unsafe for operation when the vehicle is at the railway line junction.

• 한국철도학회논문집
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• 제3권4호
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• pp.229-236
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• 2000

In this study, the unsteady flow field induced by a high-speed train passing through a tunnel is numerically simulated by using an axi-symmetric Euler Equation. The modified patched grid scheme applied to a structured grid system was used to handle the relative motion of a train. The hybrid-dimensional approach which mixed 1D and axi-symmetric dimension was used to reduce the computation time and memory storage. By employing the hybrid-dimensional approach, a long tunnel as much as 5 km was able to be simulated efficiently. The results show that the maximum pressure rise in the tunnel by the entrance of the train is a function of both train speed and train-tunnel cross-sectional area ratio. The unsteady pressure fluctuation in the tunnel and around the train was also investigated in the real condition; Korean high-speed train on the Seoul-Pusan line.

• 대한기계학회논문집B
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• 제23권2호
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• pp.234-242
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• 1999

Flow phenomena such as the pressure transients Inside a high-speed railway tunnel and the Impulsive waves at the exit of the tunnel are closely associated with the characteristics of the entry compression wave, which is generated by a train entering the tunnel. Tunnel entrance hood may be an effective means for alleviating the Impulsive waves and pressure transients. The objective of the current work is to explore the effects of the train nose shape and the entrance hood on the characteristics of the entry compression wave. Numerical calculations using the method of characteristics were applied to one-dimensional, unsteady, compressible flow field with respect to high-speed railway/tunnel systems. Two types of the entrance hoods and various train nose shapes were employed to reveal their influences on the entry compression wave for a wide range of train speeds. The results showed that the entry compression wave length increases as the train nose becomes longer and the train speed becomes lower. The entry compression wave length in the tunnel with hood becomes longer than that of no hood. Maximum pressure gradient in the compression wavefront reduces by the entrance hood. The results of the current work provide useful data for the design of tunnel entrance hood.

• 한국가시화정보학회지
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• 제16권3호
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• pp.8-15
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• 2018

Recently, as the high speed railway becomes more common, new environmental problems such as noise around tunnels are appearing. When a high speed train enters a tunnel, a compression wave in the tunnel is generated and propagated toward the tunnel exit at a sonic speed. When it reaches the tunnel exit, a part of compression wave radiates as a pulse typed impulse wave to the outside of tunnel. The impulse wave has an explosive noise. When the impulse wave is propagated around a village, it induces a serious noise or other problems to the resident. In order to solve these engineering problems, it is important to investigate the radiation characteristics of the impulse wave radiated from the tunnel exit. In this study, the effect of the length and angle of the baffle plate at the tunnel exit on the impulse wave radiated from the tunnel exit was investigated by numerical analysis. As a results, the baffle plate greatly affected the propagation of impulse wave.

• 조명전기설비학회논문지
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• 제25권2호
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• pp.32-42
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• 2011

In this paper to compare the economical efficiency of light sources for a tunnel lighting, we define a model tunnel and design tunnel lighting. And to examine economical efficiency of various tunnel lightings we compare the lighting expenses of tunnels. The results shows high pressure sodium lamps are more economical than fluorescent lamps.