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研究了多竖井城市公路隧道自然通风条件下的火灾烟气扩散规律.在某真实隧道内实施了全尺寸燃烧试验,试验过程中顶棚下方烟气温度沿纵向朝出口快速衰减,火源附近存在明显的烟气分层现象,大量烟气从竖井排出,下游排烟竖井个数多于上游.使用FDS火灾软件开展基于计算流体动力学的大涡模拟,火源区网格尺寸为0.083 m.采用并行计算技术,模拟得到的顶棚下方烟气温度、烟气前锋、竖井进/排烟均与试验数据吻合较好.进一步的数值模拟结果表明:降低环境温度或竖井组间距有助于降低顶棚下方烟气温度,同时提高竖井出口的排烟质量流量.本研究为该类隧道的设计与修建提供了理论与技术支持.
The diffusion rules of fire smoke under natural ventilation in multi-shaft urban road tunnels were studied.The full-scale combustion test was carried out in a real tunnel with the flue gas temperature below the ceiling rapidly decaying towards the outlet in the longitudinal direction and the obvious near the fire source Of flue gas stratification, a large number of flue gas discharged from the shaft, the downstream exhaust shaft more than the upstream.Using FDS fire software to carry out large-eddy simulation based on computational fluid dynamics, the ignition source zone grid size of 0.083 m. The simulation results show that the flue gas temperature below the ceiling, the flue gas front and the shaft inlet / exhaust smoke are in good agreement with the experimental data.Further numerical simulation results show that reducing the ambient temperature or the spacing of the shaft groups can help to lower the ceiling Flue gas temperature, and at the same time improve the quality of exhaust flow at the shaft exit.The research provided theoretical and technical support for the design and construction of such tunnels.