甘青隧道斜井通风管弯曲特性对局部阻力的影响研究

Study on the Influence of Bending Characteristics of Ventilation Pipes on Local Resistance in the Ganqing Tunnel Inclined Shaft

为提高高寒地区特长隧道施工过程中的通风效率,依托甘青隧道3号斜井工程,通过对以往国内外大量通风资料调研,基于流体力学原理,采用数值模拟的方法,对隧道内不同风管弯曲角度θ以及弯曲半径r下局部阻力和通风效果的变化情况进行分析,得出最优风管弯曲参数。研究结果表明:在相同的初始风速条件下,当风管弯曲角度为146°时,风管整体导流现象较为显著,风流稳定后速度最大,局部损失系数以及经过弯管时能量损失最小,对应的通风效率最高;当弯曲半径r为6 m时,射流风在弯折处的冲击力下降,可有效减小弯折处以及下游段的涡流区,使风流场分布更均匀,有效减少弯折处的局部损失,此时通风效果最优;同时,为保证高海拔隧道施工过程中的通风效果,应对风机风压进行修正。

To enhance the ventilation efficiency during the construction of extra-long tunnels in cold regions,relying on the Ganqing Tunnel No.3 Inclined Shaft Project,through investigation of a large number of ventilation data at home and abroad,based on the principle of fluid mechanics,numerical simulation method was used to analyze the bending angles(θ)of different air ducts in the tunnel and the changes in local resistance and ventilation effect under the bending radius(r).Optimal bending parameters of the air duct were obtained.The research results indicated that under the same initial wind speed conditions,when the bending angle of the air duct was 146°,the overall diversion phenomenon of the air duct was more significant.After the air flow stabilized,its velocity was maximized,the local loss coefficient and energy loss when passing through the bend were minimized,and the corresponding ventilation efficiency was the highest.When the bending radius(r)was 6 m,the impact force of the jet wind at the bend decreased,effectively reducing the vortex zones at the bend and downstream sections.This made the distribution of the air flow field more uniform,and effectively reduced local losses at the bending point.At this time,the ventilation effectiveness was optimized.At the same time,to ensure optimal ventilation during the construction of high-altitude tunnels,the wind pressure of the fan should be adjusted.