Influence of Aspect Ratio of the Exhaust Opening on Smoke Propagation in a Large Cross-section Tunnel
The point extraction system (PES) is effective and popular especially for long and large cross-section tunnels. To clearly comprehend the fire characteristics on the cross-section and correctly apply the smoke strategy, we conduct a series of numerical Computation Fluid Dynamics (CFD) simulations according to the dimensions of the South Hongmei Rd. tunnel, located in Shanghai, China. We set the tunnel in three fire scenarios i.e. 5 MW, 20 MW, and 50 MW and use three index, namely temperature, minimum visibility and carbon monoxide (CO) concentration to evaluate the effect of the PES according to the standard safety criteria on three sections with different distance from the fire source. By testing the PES, we change dimensions of smoke exhaust openings. The results show that with the same area, the slender exhaust perpendicular to the length of the tunnel can control the smoke better than the short one, especially far away from the fire source.