Reduction of the pressure gradient in railway tunnels using vented tunnel portals

Kurzfassung

The passage of a high-speed train through a vented tunnel hood was studied experimentally in model scale. The pressure history inside the tunnel was observed using pressure transducers, and the flow field outside the portal vents was recorded using an optical measurement technique. The pressure gradients inside the tunnel and the air volume exhausted through the vents are considered for different vent configurations. The experimental results are compared with theoretical predictions. The dependence of the pressure history on the position and size of the vents is explained. By optimising their configuration the pressure gradients could be reduced significantly.