隧道曲率半径对空气射流流场特性及升压效率的影响研究

Influence of tunnel curvature radius on the characteristics of air jet flow and the pressure-rise coefficient

研究了不同隧道曲率半径下射流风机诱导的空气射流在曲线隧道内的流场分布特性与射流风机升压效率。通过数值模拟软件Fluent建立了全尺寸隧道模型,曲率半径范围为75~300 m,并考虑了风机布置于直线段与曲线段入口两种典型工况。对曲线隧道内的风速分布、压力分布及升压系数进行了讨论,结果表明,当风机布置于隧道曲线段入口时,未经充分发展的空气射流直接撞击隧道壁面,在曲线隧道中的风速分布表现出明显的不对称性。隧道曲率半径越小,风流在隧道内发展均匀所需的距离也越长。而当风机布置于隧道直线段时,空气射流在进入曲线隧道前已经过充分发展。当隧道曲率半径大于120 m时,在曲线隧道中基本形成4 m/s的均匀风速。但当曲率半径小于等于120 m时,部分风流在进入曲线隧道后沿隧道弯曲壁面发展,同样会造成曲线隧道内的风速分布不均匀。将射流风机布置于直线隧道有助于提高射流风机的升压效率,且曲率半径越小,对升压系数的提升效果也越显著,对于不同的曲率半径,升压系数的提升范围在8.5%~27%。

This paper studies the pressure-rise rise coefficient and the velocity distribution characteristics of the air jet flow induced by jet fans in the curved tunnel with different curvature radii. A full-scale tunnel model is established by numerical simulation software Fluent. The curvature radius ranges from 75 m to 300 m. Two typical scenarios of the jet fans arrangement are considered, which are located at the straight tunnel section and the entrance of the curved section. The distribution of wind velocity, pressure, and pressure-rise coefficient in the curved tunnel are discussed. The results show that when the jet fans are arranged at the entrance of the curved section of the tunnel, the induced air jet is not fully developed and directly impacts the tunnel wall. The asymmetric distribution of wind velocity downstream of the curved tunnel is distinctly observed when the curvature radius of the tunnel decreases, it takes a longer distance for the air jet flow to develop evenly. However, when the jet fans are arranged in the straight section of the tunnel, the induced air jet flow can be fully developed before entering the curved tunnel. When the curvature radius of the tunnel is larger than 120 m, a uniform wind velocity of 4m/s is formed in the curved tunnel. However, when the radius of curvature is less than or equal to 120 m, the air jet flow develops along the tunnel wall after entering the curved tunnel, which can also cause an uneven wind velocity distribution downstream of the curved tunnel. The arrangement of the jet fans in the straight tunnel is helpful to improve the pressure-rise efficiency of the jet fans. As the curvature radius of the tunnel decrease, the improvement of the pressure-rise coefficient is more significant. For different curvature radius of the tunnel, the improvement percentage of pressure-rises coefficient ranges from 8.5% to 27%.