Influence of winding wall on the entrainment characteristics of air jet in curved road tunnels

摘要

The interchange structure in tunnel complexes has the characteristics of small radius and multi-ramp compared with the general tunnel, and the design of the ventilation system needs further research and optimization. This paper studied the development characteristics of air jets in urban road tunnels with small radius through commercial software FLUENT. The purpose is to provide reference for ventilation design in curved tunnels. According to the Chinese code and the survey report on tunnel complexes published by the World Road Association (PIARC), six different tunnel radii were selected to carry out this research, and the feasibility of using the realizable k-epsilon model to simulate the development of air jets was verified by full-scale experiments. The results show that negative pressure and low velocity (NPLV) zones with different degrees are found in the curved tunnel and the wind speed will be reversed. For tunnels with the radii of 150 m and 200 m, the wind speed reverses more frequently, and the dimensionless pressure minimum value will move from the convex wall to the concave one of curved tunnels. When the tunnel radius is greater than or equal to 300 m, the minimum value of dimensionless pressure increases with the increase of radius, which illustrates that the flow field in the curved tunnel gradually becomes uniform with the increase of the radius. in addition, the pressure-rise coefficient will increase with the increase of the tunnel radius. Characteristics of contaminant propagation in tunnels with different radii will be investigated in the next stage.