铁路隧道横通道临界风速研究

Study on Critical Wind Velocity of Cross Passage in Railway Tunnel

铁路隧道横通道临界风速是横通道能否有效防烟的重要参数。根据π定理和相似理论,对影响横通道临界风速的相关因素进行量纲分析,推导出横通道临界风速与隧道纵向风速、火灾热释放率、横通道防火门的高度及宽度、横通道与隧道的夹角这5个影响参数的无量纲函数关系式;通过数值模拟并对模拟数据拟合,确定横通道临界风速与这5个影响参数的关系。结果表明:当无量纲隧道纵向风速不大于0.114时,横通道临界风速随隧道纵向风速的增大呈3/7次方的增长关系,当隧道纵向风速大于0.114时,横通道临界风速随隧道纵向风速的增大呈-3/40次方的减小关系;横通道临界风速与火源热释放率呈1/3次方的增长关系、与防火门高度近似呈6/5次方的增长关系、与防火门的门宽无关、与横通道和隧道之间的夹角呈-3/8次方的减小关系。根据这些拟合结果确定无量纲函数关系式中各未知系数的取值,进而得到横通道临界风速的无量纲计算公式。

The critical wind velocity of cross passage in railway tunnel is an important parameter for the effective smoke prevention in cross passage.The dimensionless analysis of the related factors affecting the critical wind velocity in cross passage was carried out according toπtheorem and similarity theorem.The dimensionless function relations were derived between the critical wind velocity and five influence parameters,namely,the longitudinal wind speed in tunnel,heat release rate,the height and width of cross passage fireproof door as well as the angle between cross passage and tunnel.Through numerical simulation and the fitting of simulation data,the relationships between the critical wind velocity of cross passage and the five influence parameters were determined.Results show that,when the dimensionless longitudinal wind velocity of tunnel is less than 0.114,the critical wind velocity of cross passage increases with the increase of the longitudinal wind velocity of tunnel,showing a 3/7 power growth relationship.When the longitudinal wind velocity of tunnel is more than 0.114,the critical wind velocity of cross passage decreases with the increase of the longitudinal wind velocity of tunnel,showing a-3/40 power decrease relationship.The critical wind velocity of cross passage shows 1/3 and 6/5 power growth relationships with the heat release rate of fire source and the height of fireproof door respectively,a-3/8 power decrease relationship with the angle between the cross passage and tunnel,and almost independent of the width of fireproof door.According to these fitting results,the value of each unknown coefficient in the dimensionless function relations is determined,and then the dimensionless formula for the critical wind velocity of cross passage is obtained.