Journal of the Korea Academia-Industrial cooperation Society (한국산학기술학회논문지)

The Korea Academia-Industrial cooperation Society (한국산학기술학회)
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Experimental Study on the Effect of the Area Ratio between Shaft and Tunnel and Heat Release Rate on the Plug-holing Phenomena in Shallow Underground Tunnels

저심도 도로터널에서 터널과 수직환기구의 단면적 비와 열방출률이 Plug-holing 현상에 미치는 영향에 관한 실험연구

  • Hong, Kibea (Department of Automotive Engineering, Korea National University of Transportation) ;
  • Na, Junyoung (Department of Mechanical System Engineering, Chung-Ang University) ;
  • Ryou, Hong Sun (Department of Mechanical System Engineering, Chung-Ang University)
  • 홍기배 (한국교통대학교 기계자동차항공공학부 자동차공학전공) ;
  • 나준영 (중앙대학교 기계시스템엔지니어링학과) ;
  • 유홍선 (중앙대학교 기계시스템엔지니어링학과)
  • Received : 2019.02.14
  • Accepted : 2019.04.05
  • Published : 2019.04.30
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Abstract

It is difficult to design because of the plug-holing phenomenon in which the amount of smoke discharged from the vertical vent is smaller than the designed amount of smoke. In this study, the effect of cross-sectional area ratio of tunnel and natural ventilation and heat release rate of fire source on plug-holing phenomenon occurring in natural ventilation system was experimentally analyzed. In the experiment model reduced to 1/20 size, the aspect ratio of the tunnel and the vertical vent was fixed, and the influence on the plug-holing phenomenon was confirmed by varying the sectional area ratio of the tunnel and the vertical vent. Experimental results show that the plug-holing phenomenon is caused by the comparison of the smoke boundary layer temperature with the temperature in the vertical vents, and the flow and temperature distribution characteristics under the vertical vents are changed as the cross-sectional area ratio of the tunnel and vertical vents increases. The plug-holing phenomenon is affected by the cross-sectional area ratio between the tunnel and the vertical ventilation. The greater the cross-sectional area ratio, the greater the probability of plug-holing.

저심도 터널에서는 온도차에 의한 부력을 이용한 자연배기시스템이 많이 사용되고 있지만 이는 연기배출을 인위적으로 조절할 수 없다. 그러므로 자연배기시스템에서는 수직환기구에서 연기 배출량이 설계된 연기 배출량보다 적어지는 Plug-holing 현상을 고려한 설계가 필수적이다. Plug-holing 현상은 터널과 수직환기구의 형상 위치, 화원의 위치와 발열량 등에 영향을 받는다. 본 연구에서는 터널과 자연 환기구의 단면적 비와 화원의 열방출률이 자연배기시스템에서 발생하는 Plug-holing 현상에 미치는 영향에 대하여 실험적으로 분석하였다. 1/20 크기로 축소시킨 실험모델에서 터널과 수직환기구의 종횡비는 고정시키고 터널과 수직환기구의 단면적 비를 달리하여 Plug-holing 현상에 미치는 영향을 확인하였다. 화원의 열방출율은 0.55 kW, 0.98 kW, 1.67 kW로 고정시켰다. 실험결과, 연기 경계층온도와 수직환기구 내의 온도와의 비교를 통한 Plug-holing 발생을 판단하였고, 터널과 수직환기구의 단면적 비가 증가함에 따라서 수직환기구 하부의 유동과 온도분포 특성이 변함을 확인하였다. 터널 화재 시 Plug-holing 현상은 터널과 수직환기구의 단면적 비에 영향을 받으며 단면적 비가 클수록 Plug-holing 발생 가능성이 증가하였다.

Keywords

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Fig. 1. The schematic of the reduced tunnel.

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Fig. 2. Top view of tunnel and shafts in all cases[Unit : mm].

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Fig. 3. Transverse temperature distribution in tunnel. (Pool area 20.25 cm²)

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Fig. 4. Longitudinal temperature distribution in shaft (a) Pool area 6.25 cm² (b) Pool area 12.25 cm² (c) Pool area 20.25 cm²

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Fig. 5. The visualization under the shaft in small scale tunnel fire in Pool area : 20.25 cm² (a) Area ratio 0.054, (b) Area ratio 0.054 (c) Area ratio 0.090, (d) Area ratio 0.110

Table 1. Calculated heat release rate(HRR).

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Table 2. The judgment of plug-holing in all case.

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References

  1. P. L. Hinkley, "The flow of hot gases along an enclosed shopping mall a tentative theory", Fire Safety Science 807, FIRE research station, UK, pp.5-15.
  2. D. Spratt, A. Heselden, "Efficient extraction of smoke from a thin layer under a ceiling", Fire Safety Science 1001, Fire Safety Science, FIRE research station, UK, pp.5-11.
  3. J. Ji, Z.H. Gao, C.G. Fan, W. Zhong, J.H. Sun, "A study of the effect of plug-holing and boundary layer separation on natural ventilation with vertical shaft in urban road Tunnel fires" International Journal of Heat and Mass Transfer, 55, 21-22, pp.6032-6041, 2012. DOI: https://doi.org/10.1016/j.ijheatmasstransfer.2012.06.014
  4. Morgan J. Hurley, SFPE handbook of fire protection engineering, 3493, Springer, pp429-454, 2015.
  5. Quintiere, J.G., Principles of Fire Behavior, 437, Delmar, 437, 1998. DOI: https://doi.org/10.1201/9781315369655
  6. J. Ji, Z.H. Gao, J.H. Sun, "Large Eddy Simulation of stack effect on natural smoke exhausting effect in urban road Tunnel fires", International Journal of Heat and Mass Transfer, 66, pp531-542, 2013. DOI: https://doi.org/10.1016/j.ijheatmasstransfer.2013.07.057
  7. National Fire Protection Association, "NFPA 92: standard for smoke control systems", USA, 2011.
  8. Cooper, L.Y., Harkleroad, M., Quintiere, J., Rinkinen, W. "An Experimental Study of Upper Hot layer Stratification in Full-Scale Multiroom Fire Scenarios", J. Heat Transfer, 1982. DOI: https://doi.org/10.1115/1.3245194
  9. Janssens, M., Tran, H.C., "Data Reduction of Room Tests for Zone Model Validation", J. Fire Sci., 10, 528-555, 1992. DOI: https://doi.org/10.1177/073490419201000604
  10. S. Zhang, K. He, Y. Yao, M. Peng, H. Yang, J. Wang, X. Cheng, "Investigation on the critical shaft height of plug-holing in the natural ventilated tunnel fire", International Journal of Thermal Sciences, 132, pp517-533, 2018. DOI: https://doi.org/10.1016/j.ijthermalsci.2018.06.018
  11. J.G. Quintiere, "Scaling applications in fire research." Fire Safety Journal, 15.1, pp3-29, 1989 DOI: https://doi.org/10.1016/0379-7112(89)90045-3
  12. F. Mei, F. Tang, X. Ling, J. Yu, "Evolution characteristics of fire smoke layer thickness in a mechanical ventilation tunnel with multiple point extraction" Applied Thermal Engineering, 111, pp248-256, 2017. DOI: https://doi.org/10.1016/j.applthermaleng.2016.09.064
  13. C. G. Fan, J. Ji, Z. H. Gao, J. Y. Han, J. H. Sun, "Experimental study of air entrainment mode with natural ventilation using shafts in road tunnel fires", International Journal of Heat and Mass Transfer, 56.1-2, pp750-757, 2013. DOI: https://doi.org/10.1016/j.jhazmat.2009.12.019
  14. A. Hamins, T. Kashiwagi, R.R. Buch, "Characteristics of Pool Fire Burning" Fire Resistance of Industrial Fluids, American Resistance of Industrial Fluids, IN, pp.19-24. DOI: https://doi.org/10.1520/STP16278S