Abstract Field measurements regarding the dynamic process of longitudinal ventilation in tunnels show that more time is needed for wind-speed to reach a steady state in a tunnel when the running status of a jet fan is changed, which indicates a delayed effect of longitudinal ventilation in the tunnel. A dynamic response formula deduced by a theoretical equation for tunnel flow under the control of ventilators can be used to predict the strength of this delayed effect, and the theoretical results are consistent with measured data. This parametric study finds that under the same initial velocity: the more jet fans started, the shorter the amount of time for wind velocity to reach a steady state; the more jet fans that are shut, the longer it takes for wind velocity to reach a steady state; with certain numbers of jet fans being started and shut, the slower the initial velocity, and the longer it takes for wind velocity to reach a steady state; the longer the tunnel, the larger the section, and the smoother the tunnel wall, the longer it takes for wind velocity to reach a stable state and the more obvious the delayed ventilation effect.
Abstract：
Field measurements regarding the dynamic process of longitudinal ventilation in tunnels show that more time is needed for wind-speed to reach a steady state in a tunnel when the running status of a jet fan is changed, which indicates a delayed effect of longitudinal ventilation in the tunnel. A dynamic response formula deduced by a theoretical equation for tunnel flow under the control of ventilators can be used to predict the strength of this delayed effect, and the theoretical results are consistent with measured data. This parametric study finds that under the same initial velocity: the more jet fans started, the shorter the amount of time for wind velocity to reach a steady state; the more jet fans that are shut, the longer it takes for wind velocity to reach a steady state; with certain numbers of jet fans being started and shut, the slower the initial velocity, and the longer it takes for wind velocity to reach a steady state; the longer the tunnel, the larger the section, and the smoother the tunnel wall, the longer it takes for wind velocity to reach a stable state and the more obvious the delayed ventilation effect.
WU Ke,
Zhu-Kai,
Tan-Zhen etc
.On the Mechanism and Influence of the Delayed Effect of Longitudinal Ventilation in Urban Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2014,V51(5): 139-144
2014, Vol. 51 