Abstract
Combustion efficiency in tunnel fires was measured using a 1:20 scale model tunnel with a 0.25-m height, H, while varying the length of the model tunnel, L, as the experimental parameter. A series of fire experiments was conducted to confirm whether combustion efficiency was affected by the tunnel length, L. A dimensionless tunnel length defined as L* = L/H was selected as L* = 8, 16, 24, 32, 40, and 48, corresponding 40–240 m in full scale. The results showed that combustion efficiency was not affected by the dimensionless tunnel length ranging from L* = 8–32, and its average value was 90%. However, when the dimensionless tunnel length was L* = 40 or more, part of the smoke flowing under the ceiling of the model tunnel descended to the floor, and the smoke descent phenomenon dramatically changed the flow dynamics of the smoke. As a result, the flame on the gas burner became unstable, and ultimately the ghosting flame phenomenon was observed close to the fire source. We qualitatively discussed the cause of the ghosting flame phenomenon, in addition to combustion efficiency.
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Abbreviations
- B :
-
Bias limit
- C p :
-
Specific heat at constant pressure (kJ/kg K)
- E′ :
-
Net heat of combustion of oxygen consumed (E′ = 17.2 MJ/m3)
- E″ :
-
Net heat of combustion of oxygen consumed in the burning of carbon monoxide (E″ = 23.1 MJ/m3)
- f :
-
Fraction of depleted oxygen going into the formation of carbon monoxide (–)
- g :
-
Gravitational acceleration (m/s2)
- H :
-
Tunnel height (m)
- ΔHT:
-
Lower calorific value of propane gas (ΔHT = 46 × 103 kJ/kg)
- L :
-
Tunnel length (m), length (m)
- \( \dot{m} \) :
-
Mass flow rate of the propane gas (kg/s)
- Q :
-
Heat release rate (kW)
- Q ch :
-
Chemical heat release rate (kW)
- Q T :
-
Heat release rate for complete combustion (kW)
- \( S\bar{x} \) :
-
Precision index of average
- t :
-
Student’s t value (–), time (s)
- T :
-
Temperature (K)
- ΔT:
-
Rise in temperature (K)
- U :
-
Measurement uncertainty with a 95% confidence level
- V :
-
Velocity (m/s)
- V A :
-
Volume flow rate air referred to standard conditions (m3/s)
- x :
-
X-coordinate (m)
- X i :
-
Volume fraction of gas species i (–)
- χ :
-
Combustion efficiency (–)
- \( \phi \) :
-
Fraction of oxygen-depleted (–)
- γ :
-
Scale ratio (–)
- θ i :
-
Sensitivity coefficient for a chemical heat release rate of a parameter i (e.g. θT = ∂Qch/∂T)
- * :
-
Dimensionless value
- 0:
-
Ambient condition
References
Tewarson, A. (2002). Generation of heat and chemical compounds in fires. In P. J. DiNenno, et al. (Eds.), SFPE handbook of fire protection engineering (3rd ed., Vol. 3, pp. 82–161). Gaithersburg: Society of Fire Protection Engineers.
Hu, L. H., Huo, R., Wang, H. B., Li, Y. Z., & Yang, R. X. (2007). Experimental studies on fire-induced buoyant smoke temperature distribution along tunnel ceiling. Building and Environment, 42, 3905–3915.
Takeuchi, S., Aoki, T., Tanaka, F., & Moinuddin, K. A. M. (2017). Modeling for predicting the temperature distribution of smoke during a fire in an underground road tunnel with vertical shafts. Fire Safety Journal, 91, 312–319.
Gao, Z. H., Ji, J., Fan, C. G., & Sun, J. H. (2016). Determination of smoke layer interface height of medium scale tunnel fire scenarios. Tunnelling and Underground Space Technology, 56, 118–124.
Zukoski, E. E., Kubota, T., & Cetegen, B. (1980). Entrainment in fire plumes. Fire Safety Journal, 3, 107–121.
Parker, W. J. (1982). Calculations of the heat release rate by oxygen consumption for various applications, NBSIR 81-2427-1. Gaithersburg: National Bureau of Standards (U.S.).
Ingason, H., Li, Y. Z., & Lönnermark, A. (2015). Tunnel fire dynamics (pp. 485–488). Berlin: Springer.
Vauquelin, O., & Telle, D. (2005). Definition and experimental evaluation of the smoke “confinement velocity” in tunnel fires. Fire Safety Journal, 40, 320–330.
Tanaka, F., Takezawa, K., Hashimoto, Y., & Moinuddin, K. A. M. (2018). Critical velocity and backlayering distance in tunnel fires with longitudinal ventilation taking thermal properties of wall materials into consideration. Tunnelling and Underground Space Technology, 75, 36–42.
American Society of Mechanical Engineers. (1985). ASME Performance Test Codes, Supplement on Instruments and Apparatus, Part 1, Measurement Uncertainty, PTC19.1-1985.
Audouin, L., Such, J. M., Malet, J. C., & Casselman, C. (1997). A real scenario for a ghosting flame. Fire Safety Science, 5, 1261–1272.
He, Q., Li, C., Lu, S., Wang, C., & Zhang, J. (2015). Pool fires in a corner ceiling vented cabin: ghosting flame and corresponding fire parameters. Fire Technology, 51, 537–552.
Acknowledgements
This work was supported by JSPS KAKENHI Grant Number JP17K01292. The authors appreciate the support of JSPS.
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Ishikawa, T., Kasumi, K., Tanaka, F. (2020). Effects of Tunnel Length on Combustion Efficiency in Tunnel Fires. In: Wu, GY., Tsai, KC., Chow, W.K. (eds) The Proceedings of 11th Asia-Oceania Symposium on Fire Science and Technology. AOSFST 2018. Springer, Singapore. https://doi.org/10.1007/978-981-32-9139-3_77
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DOI: https://doi.org/10.1007/978-981-32-9139-3_77
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