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Numerical Studies on Thermally-Induced Air Flow in Sloping Tunnels with Experimental Scale Modelling Justifications

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Abstract

Study of smoke movement or air flow due to fire in sloping tunnels is important in designing smoke control systems. In contrast to a horizontal tunnel, there is an acceleration along the longitudinal axis due to smoke buoyancy. This phenomenon together with thermal radiation would lead to a complicated heat transfer mechanism of the ceiling jet in sloping tunnels. In the present work, thermally induced air flow arising from fire in sloping tunnels was studied via numerical simulations using the Computational Fluid Dynamics code FLUENT. Prior to the application of FLUENT in simulating the air flow under different conditions, scale model experiments were carried out and the results were compared with simulation results, to establish the reliability of FLUENT in simulating fires in sloping tunnels. For this purpose, a tunnel section model of length 3 m, width 0.8 m and height 1 m was constructed, with a 1.5 kW electrical heating source to model fire. Hot air movement pattern driven by the electric heater was studied with the tunnel inclined at 0°, 10°, 20° and 30° to the horizontal. Four cases of the same configuration as the scale tunnel experiments were simulated using FLUENT, with predicted results agreeing well with experimental results. Having established the suitability of FLUENT in simulating air flow due to fire in sloping tunnels, numerical simulations were carried out to study air flow in sloping tunnels with different scenarios, that is, for tunnels with different gradients and with fire located at different positions in the tunnel. Macroscopic number on heat transfer, including the Rayleigh number Ra, the average and local Nusselt number Nuave for sloping tunnels were also studied from the measured results. The correlation between Nuave and Ra, which shows the effect of hydrodynamic properties on relative dominance of heat transfer in tunnel fire, was also discussed.

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Abbreviations

\( C_{\varepsilon 1} \) :

Model constant, 1.44

\( C_{\varepsilon 2} \) :

Model constant, 1.92

\( C_{\varepsilon 3} \) :

Model constant, \( C_{\varepsilon 3} = \tanh \left| {\frac{v}{u}} \right| \)

\( G_{b} \) :

Generation of turbulent kinetic energy due to buoyancy [kg/(m s3)]

\( G_{k} \) :

Generation of turbulent kinetic energy due to the mean velocity gradients [kg/(m s3)]

h :

Convective heat transfer coefficient [W/(m2 °C)]

H :

Height of the tunnel (m)

I :

Radiant intensity [W/(m2 sr)]

\( k \) :

Turbulent kinetic energy (m2/s2); conductivity [W/(m K)]

L :

Length of the tunnel (m)

\( L_{\text{m}} \) :

Length of model geometry (m)

\( L_{\text{real}} \) :

Length of real geometry (m)

Nu :

Nusselt number

\( \dot{Q}_{\text{m}} \) :

Heat release rate of model fire (kW)

\( \dot{Q}_{\text{real}} \) :

Heat release rate of real fire (kW)

Ra :

Rayleigh Number

s :

Radiation path length (m)

T :

Gas temperature (°C); surface temperature (K)

W :

Width of the tunnel (m)

y :

Non-dimensional distance

α :

Gas absorption coefficient (1/m)

\( \varepsilon \) :

Rate of dissipation of turbulence kinetic energy (m2/s3)

\( \rho \) :

Gas density (kg/m3)

\( \mu \) :

Dynamic viscosity (Pa s)

\( \sigma_{k} \) :

Model constant, 1.0

\( \sigma_{\varepsilon } \) :

Model constant, 1.3

θ :

Tunnel angle (°)

Θ :

Non-dimensional temperature

κ :

Stefan–Boltzmann constant, \( \kappa = 5.672\, \times \,10^{ - 8} \,{\text{Wm}}^{ - 2} {\text{K}}^{ - 4} \)

\( \beta \) :

Compression coefficient

0:

Ambient condition

ave:

Average value

i, j:

ith or jth direction

t:

Turbulent

wall:

Wall properties

fluid:

Fluid properties

w:

Near wall region

h:

Hot

c:

Cold

References

  1. Chow WK, Wong KY, Chung WY (2010) Longitudinal ventilation for smoke control in a tilted tunnel by scale modeling. Tunn Undergr Space Technol 25(2):122–128

    Article  Google Scholar 

  2. Zou JF, Gao Y, Dong H, Chow WK (2010) Scale model studies on heater-induced hot air layer in a tilted duct. In: Paper presented at sixth international seminar on fire and explosion hazards, 11–16 Apr 2010, Weetwood Hall, Leeds, UK

  3. Chow WK, Chan HK, Tso CY (2012) Application of scale models in designing smoke control systems in big buildings. In: Paper presented at 2nd international high performance buildings conference, 16–19 July 2012, Purdue University, West Lafayette, Indiana, USA

  4. Apple Daily (2007) West rail fire. 15 Feb 2007 (in Chinese)

  5. Ingason H, Lönnermark A (2005) Heat release rates from heavy goods vehicle trailer fires in tunnels. Fire Saf J 40(7):646–668

    Article  Google Scholar 

  6. NFPA (2011) NFPA 502-2011 standard for road tunnels, bridges, and other limited access highways. National Fire Protection Association, New York

    Google Scholar 

  7. Fire Services Department (2005) Code of practice for minimum fire service installations and equipment and inspection, testing and maintenance of installations and equipment. Hong Kong Special Administrative Region

  8. Ministry of Housing and Urban-Rural Development of the People’s Republic of China (2014) GB 50016-2014, code for fire protection design of buildings. China Planning Press, Beijing

  9. Ministry of Communications of China (2000) JTJ 026.1-1999, specification for design of ventilation and lighting of highway tunnel. China Communication Press, Beijing

  10. Japan Road Association (2008) Road tunnel technical standards, Ventilation edn. Japan Road Association, Tokyo

    Google Scholar 

  11. Chow WK (1998) On smoke control for tunnels by longitudinal ventilation. Tunn Undergr Space Technol 13(3):271–275

    Article  Google Scholar 

  12. Thomas PH (1985) The movement of buoyant fluid against a stream and the venting of underground fires. Fire research note 351, Fire Research Station, Borehamwood, UK

  13. Ip AKY, Luo MC (2005) Smoke control in pedestrian subway. In: Proceedings of the Hubei—Hong Kong joint symposium 2005, Wuhan, Hubei, China, 30 June–3 July 2005, pp 70–79

  14. Zou JF, Gao Y, Chow WK (2012) Numerical studies on laminar natural convective air flow in inclined channels. J Fluid Therm Sci 1(2):157–177

    Google Scholar 

  15. Chow WK (2007) Design fire size for vehicular tunnels and potential problems in operating longitudinal ventilation system. Fire Safety Reform and Development Forum, Kunming, Yunnan, China

  16. Zukoski EE (1995) Properties of fire plumes. In: Cox G (ed) Combustion fundamentals of fire. Academic Press, London, pp 184–189

    Google Scholar 

  17. Drysdale DD, Macmillan AJR, Shilitto D (1992) The King’s cross fire: experimental verification of the ‘Trench effect’. Fire Saf J 18(1):75–82

    Article  Google Scholar 

  18. Oka Y, Atkinson GT (1995) Control of smoke flow in tunnel fires. Fire Saf J 25:305–322

    Article  Google Scholar 

  19. Atkinson GT, Wu Y (1996) Smoke control in sloping tunnel. Fire Saf J 27:335–341.

    Article  Google Scholar 

  20. Wu Y, Xing HJ, Atkinson GT (2000) Interaction of fire plume with inclined surface. Fire Saf J 35:391–403

    Article  Google Scholar 

  21. Hwang CC, Edwards JC (2005) The critical ventilation velocity in tunnel fires—a computer simulation. Fire Saf J 40:213–244

    Article  Google Scholar 

  22. Ballesteros-Tajadura R, Santolaria-Morros C, Blanco-Marigorta E (2006) Influence of the slope in the ventilation semi-transversal system of an urban tunnel. Tunn Undergr Space Technol 21:21–28

    Article  Google Scholar 

  23. Kim SR, Bae SY, Ryou HS, Kim NI, Lee SH (2007) Slope effect on critical velocity in tunnel fires. In: Poster paper in annual fire conference 4–5 April 2007. Building and Fire Research Laboratory, National Institute of Standards and Technology

  24. Ko GH, Kim SR, Ryou HS (2010) An experimental study on the effect of slope on the critical velocity in tunnel fires. J Fire Sci 28:27–47

    Article  Google Scholar 

  25. Hu LH, Chen LF, Wu L, Li YF, Zhang JY, Meng N (2013) An experimental investigation and correlation on buoyant gas temperature below ceiling in a slopping tunnel fire. Appl Therm Eng 51:246–254

    Article  Google Scholar 

  26. Oka Y, Kakae N, Imazeki O, Inagaki K (2013) Temperature property of ceiling jet in an inclined tunnel. In: Proceedings of the 9th Asia-Oceania symposium on fire science and technology, procedia engineering, vol 62, pp 234–241

  27. ANSYS FLUENT http://www.ansys.com/Products/Fluids/ANSYS-Fluent

  28. Lin P, Lo SM, Li T (2014) Numerical study on the impact of gradient on semi-transverse smoke control system in tunnel. Tunn Undergr Space Technol 44:68–79

    Article  Google Scholar 

  29. Memorial Tunnel Fire Ventilation Test Program (MTFVTP) (1995) Test report. Technical report. Massachusetts Highway Department and Federal Highway Administration

  30. Yang D, Hu LH, Huo R, Jiang YQ, Liu S, Tang F (2010) Experimental study on buoyant flow stratification induced by a fire in a horizontal channel. Appl Therm Eng 30:872–878

    Article  Google Scholar 

  31. Oka Y, Imazeki O (2014) Temperature and velocity distributions of a ceiling jet along an inclined ceiling—part 1: approximation with exponential function. Fire Saf J 65:41–52

    Article  Google Scholar 

  32. Oka Y, Imazeki O (2015) Temperature distribution within a ceiling jet propagating in an inclined flat-ceilinged tunnel with natural ventilation. Fire Saf J 71:20–33

    Article  Google Scholar 

  33. Huo Y, Gao Y, Chow WK (2015) A study on ceiling jet characteristics in an inclined tunnel. Tunn Undergr Space Technol 50:32–46

    Article  Google Scholar 

  34. Byram GM (1966) Scaling laws for modeling mass fires. Pyrodynamics 4:271–284

    Google Scholar 

  35. Quintiere JG (1989) Scaling applications in fire research. Fire Saf J 15: 3–29

    Article  Google Scholar 

  36. Satoh K (1991) Modeling of fire detection in air-conditioning rooms. In: Proceedings of 12th joint panel meeting of the UJNR panel on fire research and safety, Oct 27–Nov 2, 1991, Tsukuba, Ibaraki, Japan

  37. Lui GCH, Chow WK (2003) A short note on experimental verification of zone models with an electric heater. Int J Eng Perform Based Fire Codes 5(2):30–32

    Google Scholar 

  38. Wilcox DC (1994) Turbulence modeling for CFD. DCW Industries, Inc., La Cañada Flintridge

    Google Scholar 

  39. Launder BE, Spalding DB (1972) Lectures in mathematical models of turbulence. Academic Press, London

    MATH  Google Scholar 

  40. Henkes RAWM, van der Flugt FF, Hoogendoorn CJ (1991) Natural convection flow in a square cavity calculated with low-Reynolds-number turbulence models. Int J Heat Mass Transf 34:1543–1557

    Article  Google Scholar 

  41. Carvalho MG, Farias T, Fontes P (1991) Predicting radiative heat transfer in absorbing, emitting, and scattering media using the discrete transfer method. Fundam Radiat Heat Transf 160:17–26

    Google Scholar 

  42. Fire Dynamics Simulator https://pages.nist.gov/fds-smv/

  43. Dixit HN, Babu V (2006) Simulation of high Rayleigh number natural convection in a square cavity using the lattice Boltzmann method. Int J Heat Mass Transf 49(3–4):727–739

    Article  MATH  Google Scholar 

  44. Herbert OJ (2004) Prandtl’s essentials of fluid mechanics, 2nd edn. Springer, New York

    Google Scholar 

  45. Amano R, Izushi Y, Kurioka H, Kuwana H, Tsuruda T, Suzuki T, Ogawa Y (2005) Water screen as partitioning technology. In: Poster presentation, 8th IAFSS 2005—the 8th international symposium on fire safety science, 18–23 Sep 2005, Tsinghua University, Beijing

  46. Fang Z (2013) Selection of fire suppression system for urban tunnels and the effect on smoke movement. In: A talk at the 4th fire education and science technology development forum, Southwest Jiaotong University, Chengdu, Sichuan, China, 25–26 July 2013

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Acknowledgements

The work described in this paper was supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China for the Theme-Based Research Scheme Project “Safety, Reliability, and Disruption Management of High Speed Rail and Metro Systems” (Project Number: T32-101/15-R).

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Authors and Affiliations

  1. Department of Building Services Engineering, Research Centre for Fire Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

    W. K. Chow

  2. College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin, Heilongjiang, China

    Y. Gao, J. F. Zou & Q. K. Liu

  3. Department of Architecture and Civil Engineering, City University of Hong Kong, Kowloon, Hong Kong, China

    C. L. Chow & L. Miao

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  1. W. K. Chow
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Correspondence to W. K. Chow.

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Chow, W.K., Gao, Y., Zou, J.F. et al. Numerical Studies on Thermally-Induced Air Flow in Sloping Tunnels with Experimental Scale Modelling Justifications. Fire Technol 54, 867–892 (2018). https://doi.org/10.1007/s10694-018-0713-3

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