地铁隧道活塞风演化规律及其对通风安全的影响

Evolution Law of Piston Wind in Subway Tunnel and Its Influence on Ventilation Safety

由于地铁隧道的环境相对狭长封闭,列车行驶形成的活塞风会对隧道内流场产生显著的影响,从而影响地铁隧道通风安全。以单洞单线类矩形区间隧道内行驶的B型地铁列车为研究对象,采用Fluent动网格方法对地铁隧道内匀速直线行驶列车形成的活塞风演化规律进行数值模拟,着重分析了不同阻塞比下隧道内行驶列车导致的隧道整体流场变化以及列车经过隧道某断面处流场变化,并与数学模型预测结果进行对比。结果表明:当列车在隧道内启动并以速度为10 m/s匀速直线行驶时,隧道内活塞风风速逐渐增大,待稳定后列车以4.09 m/s速度匀速行驶时,隧道内活塞风风速保持不变,其与数学模型预测结果相吻合;当列车经过隧道某断面处时,该断面处的活塞风风向先向前、再向后、最后向前,活塞风风速呈现波浪式变化,最大回流风风速为9.75 m/s;随着阻塞比α增大,隧道内活塞风风速增大,对隧道内空气流动的影响增强;当α=0.2、0.4、0.49时,列车尾端产生负压涡流区,隧道内活塞风风速波动明显;当α=0.6、0.8时,列车尾端只产生负压区,隧道内流场较为稳定。

Due to the narrow and confined environment of the subway tunnel,the piston wind formed by train running has a significant impact on the flow field in the tunnel,affecting ventilation safety of the sub-way tunnel.Taking the B-type subway train running in the single-hole and single-line rectangular interval tunnel as the research object,the Fluent dynamic mesh method is used to numerically simulate the evolu-tion law of piston wind formed by a train running in a uniform straight line in the subway tunnel.The chan-ges of the overall flow field of the tunnel and the flow field at a certain section of the tunnel caused by a train running in the tunnel under different blockage ratios are studied and compared with the prediction re-sults of the mathematical model.The results show that when a train starts and runs in a uniform straight line at speed of 10 m/s,the piston wind velocity in the tunnel gradually increases and remains unchanged at 4.09 m/s after stabilization,which is consistent with the prediction results of the mathematical model.When the train passes through a section of the tunnel,the wind direction of the piston wind at the section is first forward,then backward,and finally forward.The wind velocity of the piston wind changes in waves.The maximum velocity of return wind is 9.75 m/s.With the increase of the blockage ratio(a),the piston wind velocity in the tunnel increases and the influence on the air flow in the tunnel is enhanced.When α=0.2,0.4,0.49,a negative pressure vortex zone is formed at the train tail,and the piston wind velocity in the tunnel fluctuates obviously.When α=0.6,0.8,there is only a negative pressure zone at the train tail,and the flow field in the tunnel is stable.