In this paper, FDS (Fire Dynamics Simulator) is used to study the smoke flow structure of large tunnel fires at high altitude under natural ventilation conditions. The results of the study show that in a naturally ventilated tunnel, there is a "critical point" of smoke flow related to the distance from the fire source, and the thickness of the smoke layer and the mass flow rate of the smoke increase along the distance from the fire source before the "critical point", and increase along the distance from the fire source after the "critical point".As the altitude of the tunnel increases, the smoke mass flow rate decreases, the thickness of the smoke layer increases, and the location of the "critical point" is closer to the fire source. The analyses show that the altitude promotes the settling of smoke and hinders the longitudinal flow of smoke. Furthermore, it has been demonstrated that the rate of heat release rate from the fire source is a significant factor in determining the role of altitude. The critical distance associated with the "critical point" in the process of smoke flow is further defined, and the prediction model for the change of dimensionless critical distance with altitude is given, and the results are in good agreement.
Zhang Yao
,
Yin Yimeng
,
Guo Qinghua
,
Yan Zhiguo
. Characteristics of Fire Smoke Flow in High-Altitude Long Tunnel[J]. Chinese Journal of Underground Space and Engineering, 2024
, 20(S2)
: 907
-915
.
DOI: 10.20174/j.JUSE.2024.S2.46
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