The authors examine the
effects of natural wind in tunnels on fire smoke diffusion characteristics,
with the aim of providing a scientific basis for optimizing tunnel fire
ventilation and smoke exhaust systems. The natural wind conditions in the
Yunshan extra-long highway tunnel are
monitored on site to determine its distribution pattern. In addition, a three-dimensional fire dynamics model is developed through a numerical
simulation to evaluate the temperature and smoke fields under the influence of
smoke exhaust through a shaft, where the effects of natural wind blowing from
both the same and opposite directions are analyzed. Key findings include: (1)
The ambient temperature in the tunnel maintains a substantial and stable
thermal potential difference between the inside and outside, promoting the
formation of natural wind, with a maximum speed exceeding 5.0 m/s. (2) At a
longitudinal wind speed of 3.0 m/s, natural wind from the same direction increases the range of
temperature rise within the tunnel while lowering the temperature in the lower
section between the fire source and exhaust outlet. (3) The natural wind from
opposite directions inhibits the diffusion of the high-temperature
field, with temperatures between the fire source and smoke outlet rising as
natural wind speed increases. (4) When the natural wind speed from the same
direction does not exceed 2.5 m/s, smoke concentration peaks between the fire source and the smoke
outlet, with higher concentrations in the upper part of the tunnel as compared
to the lower part. (5) At wind speeds exceeding 3.5 m/s from the same
direction, the stratification of downstream flue gas is disrupted, leading to a
more uniform distribution of flue gas. (6) Natural wind from opposite
directions helps to limit the downstream spread of smoke from the exhaust port:
as wind speed increases, the distance that smoke spreads downstream decreases
and approaches a constant value. (7) Both natural wind from the same and
opposite directions reduce smoke exhaust efficiency. Specifically, at a wind
speed of 4.0 m/s, the smoke exhaust efficiency of the shaft decreases by 22.43%
and 21.55%, respectively, compared to conditions without natural wind. The
effects of natural wind from the same direction on the smoke exhaust efficiency
are greater than those of wind from opposite directions.
CHEN Li
,
LIU Bing
,
CAO Zhi
,
CHEN Jiajia
,
ZHANG Heng
,
ZHANG Zhiqiang
. Influence of Natural Wind
on Fire Smoke Diffusion Characteristics Through
Shafts in Extra-Long Highway Tunnels[J]. Tunnel Construction, 2025
, 45(2)
: 315
-323
.
DOI: 10.3973/j.issn.2096-4498.2025.02.007
