• Title, Summary, Keyword: Critical Tunnel length

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Theoretical x-t Diagram Analysis on Pressure Waves of High Speed Train in Tunnel (터널에서의 고속철도 압력파에 관한 X-t선도 이론 해석)

  • 남성원;권혁빈
    • Journal of the Korean Society for Railway
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    • v.7 no.3
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    • pp.200-207
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    • 2004
  • Theoretical study has been conducted to clarify pressure characteristics of KTX (Korea Train eXpress) in tunnel. The severe pressure change in tunnel may give rise to the ear-discomfort for passenger and fatigue for car body. Critical tunnel lengths which are induced by x-t diagram analysis can be applied to the experimental results measured by using the running test with atmospheric pressure sensors and portable data acquisition system in previous study. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. We found that there are similar patterns of external pressure change for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity. And, the patterns of pressure wave in tunnel are classified into eight groups.

Theoretical Study on the Characteristics of Pressure Change of High Speed Train in Tunnels (터널통과시 고속 철도 압력 변동 특성에 관한 이론적 연구)

  • Nam, Seong-Won;Kwon, Hyeok-Bin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.9
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    • pp.1042-1050
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    • 2004
  • Theoretical study has been conducted to clarify pressure characteristics of KTX(Korea Train eXpress) in tunnel. The severe pressure change in tunnel may give rise to the ear-discomfort for passenger and fatigue for car body. The external and internal pressure of rolling stock have been measured by using the running test with atmospheric pressure sensors and portable data acquisition system in high speed train. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. We found that there are similar patterns of external pressure change for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity. And, the patterns of pressure wave in tunnel are classified into eight groups.

A Study on the x-t diagram Characteristics of Pressure Change of High Speed Train in Tunnels (터널에서의 고속철도 압력 변화의 x-t선도 특성에 관한 연구)

  • Nam, Seong-Won
    • Proceedings of the KSME Conference
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    • pp.1655-1660
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    • 2004
  • Theoretical study has been conducted to clarify pressure characteristics of KTX(Korea Train eXpress) in tunnel. The external and internal pressure of rolling stock have been measured by using the atmospheric pressure sensors and portable data acquisition system on Seoul-Busan high speed railroad line. These pressure change may give rise to the ear-discomfort for passenger and fatigue for car body. In this study, the tunnels from 200m to 4000m in length have been chosen for the investigation of tunnel length effects. From the results of experiment, the pattern of pressure change generally agrees to RTRI's experimental result for Shinkansen. We found that there are similar patterns of external pressure variation for each critical tunnel length. The critical tunnel lengths are governed by train speed, train length and sonic velocity.

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A Study on the Characteristics of Internal and External Pressure Variation for KTX (KTX차량 내외부의 압력변동 특성에 관한 연구)

  • 남성원
    • Journal of the Korean Society for Railway
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    • v.7 no.1
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    • pp.26-31
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    • 2004
  • A study is conducted to clarify internal and external pressure variation of passenger cabin for KTX. These pressure variation may give rise to the ear-discomfort for passenger and fatigue for carbody. In this study, the pressure variation of interior, gangway and exterior of KTX passenger car is measured by using the atmospheric pressure sensors and portable data acquisition system. The tunnel from 4000m to 200m in length are chosen far the investigation of tunnel length effects. From the results of experiment, the pressure variation of interior per second is under the ear-discomfort limitation in all of tunnel. And, We found that there are similar patterns of exterior pressure variation for each critical tunnel length. These results generally agree to RTRI's experimental result fur Shinkansen.

Experimental Study on the Characteristics of Pressure Variation of KTX Passing Through Tunnel

  • Nam, Seong-Won
    • International Journal of Railway
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    • v.1 no.4
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    • pp.169-174
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    • 2008
  • Experimental study has been conducted to clarify the internal and external pressure variation characteristics for KTX(Korea Train eXpress) passing through tunnel. Abrupt pressure variation gives rise to the ear-discomfort for passenger and fatigue for car body. In this study, the internal and external pressure variation are measured by using KTX real train experiment and on-board portable data acquisition system in Gyeongbu high speed commercial line. The tunnels from 200 m to 4000 m in length are chosen for the investigation of tunnel length effects. From the results of experiment, the internal pressure variation rate for all the test tunnels is lower than the standard criteria of 200 Pa/s. And, the critical tunnel lengths for pressure wave pattern are classified into 7 groups by using the theoretical L-t diagram analysis.

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The Reduced Model Test for the Determination of Ventilation Velocity to Prevent Backflow in Uni-directional Road Tunnel during a Fire Disaster (일방향 도로터널내 화재 발생시 역류를 막는 환기속도결정에 관한 축소모형실험)

  • 유영일;이희근
    • Tunnel and Underground Space
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    • v.8 no.2
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    • pp.107-117
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    • 1998
  • In the case of a fire disaster in a uni-directional road tunnel, it is important to determine the critical ventilation velocity to prevent the backflow travelling toward the tunnel exit where vehicles are stopped. The critical ventilation velocity is horizontal velocity to prevent hot smoke from moving toward the tunnel exit. According to Froude modelling, the model tunnel whcih was 300mm in diameter and 21 m in length was made of acryl tubes. Inner section of acryl tubes was clothed with polycarbonate. 1/20 scaled model vehicles were installed to simulate the situation that vehicles are stopped in the tunnel exit. Methanol in a pool type burner was burned in the middle of tunnel to simulate a fire hazard. In this study, the basis of determining the critical ventilation velocity is the ventilation flow rate that is able to maintain the allowable CO concentration in the tunnel section. We assumed that the allowable CO concentration was backflow dispersion index. Futhermore, We intended to find out CO distribution and temperature distribution according as we changed ventilation velocity. The results of this study were that no backflow happened when ventilation velocity was 0.52 m/s in the case of 5.75 kW. If we adapt these results of a fire disaster releasing 10MW heat capacity in real tunnel which is 400m in length, no backflow happens when ventilation velocity is 2.31m/s. After we figured out dimensionless heat release rate and dimensionless ventilation velocity of model test and those of real test to verify experimental correctness, we tried to find out correlation between experimental results of model tunnel and those of real tunnel.

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The Analysis of Ventilation of Road Tunnel in Fire (도로터널 화재시의 환기분석)

  • Kom, Sung-Joon;Ryu, Jin-Woong
    • Journal of Industrial Technology
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    • v.23 no.A
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    • pp.9-13
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    • 2003
  • Numerical experiments are done by a commercial code, PHOENICS to evaluate the backlayer phenomenon of smoke in case of the road tunnel fire. The independent and dependent variables are ventilation air velocity and the length of backlayer of smoke respectively. Hybrid scheme and ${\kappa}-{\varepsilon}$ turbulence model are adopted in the simulation process and mass residual is used as a convergence criterion. The experimental results say that the length of backlayer is reduced with the increase of ventilating air velocity and that there is a critical air velocity which prevents from the onset of backlayering phenomena. One finds that there is a fresh air region near the bottom of tunnel which could make the passenger escape safely from the polluted region by smoke. These phenomena come from the vertical stratification of the smoke air mixture in the tunnel.

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Analysis of the air tightness for high speed train (고속전철의 기밀 거동 해석)

  • 정병철;염경안;강석택
    • Proceedings of the KSR Conference
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    • pp.220-224
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    • 2002
  • As the train run through the tunnels, especially at high speed, pressure shock developed by the running train gives the influence on the pressure fluctuation inside the tunnel and consequently, inside the car. This pressure changes and pressure gradient is closely related with the tunnel section, train speed, air tightness of the train, length of the tunnel, etc. This study includes the analysis of the pressure behavior at the varied train speed and tunnel length. The results show that train speed affects the pressure gradient inside the car almost linearly, and that there exist the critical tunnel lengths that gives the maximum value of pressure change and pressure gradient, respectively.

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The Change of Backlayer Length with the Ventilation Air Velocity in the Tunnel Fire (터널화재에서 환기속도와 backlayer의 길이변화)

  • 김성준;이민규
    • Fire Science and Engineering
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    • v.17 no.3
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    • pp.50-54
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    • 2003
  • The backlayer phenomena of smoke in the road tunnel is evaluated through numerical experiments. A commercial code, PHOENICS is used to simulate smoke flow in the road tunnel. The independent and dependent variables are ventilation air velocity and the length of backlayer of smoke respectively. Hybrid scheme and $textsc{k}-\varepsilon$ turbulence model is adopted in the simulation process and mass residual is used as a convergence criterion. The experimental results say that the length of backlayer is reduced linearly with the increase of ventilating air velocity and that there is a critical air velocity which prevents from the onset of backlayering phenomena. One finds that there is a fresh air region near the bottom of tunnel which could make the passenger escape from the region polluted by smoke. These phenomena come from the severe vertical stratification of the smoke air mixture in the tunnel.

A Study on the Calculation of Critical Velocity by Fire Intensity (화재강도에 따른 임계풍속산정에 관한 연구)

  • Kim, Jong-Yoon;Lim, Kyung-Bum;Seo, Tae-Beom;Rie, Dong-Ho;Yoo, Ji-Oh
    • Fire Science and Engineering
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    • v.20 no.4
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    • pp.91-97
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    • 2006
  • This study was executed to review feasibility on the calculation of critical velocity with a reduced model of an actual tunnel in order to establish the optimum fire protection system for a fire in road tunnels. In a scaled model about 1/29 of an actual tunnel based on the Froude scaling, critical velocity was calculated by visualizing smoke flow and analyzing correlation with temperature. In the experiment, critical velocities at which smoke backflow length became zero showed a small difference within about 5% compared to results calculated by the Kennedy formula, and the relation between smoke flow and temperature distribution appeared similarly without getting greatly influenced by changes in fire intensity.