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ISSN Druckformat: 1065-3090
ISSN Online: 1940-4336
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SIMULATION OF VENTILATED TUNNEL FIRES USING FINE-BUBBLE MODELING TECHNIQUE
ABSTRAKT
The main objective of this work was to visualize the buoyancy-induced flow in a road tunnel model that is analogous to the thermally driven smoke flow in the case of a tunnel fire. In the beginning, the tunnel model was made of Plexiglas and a large water tank was built using tempered glass. A cathode was placed within the tunnel model so that fine hydrogen bubbles were released as a result of the electrolysis of water. The hydrogen bubbles rose and eventually left the tunnel model enabling the simulation of the fire source in the case of a tunnel fire. Pictures were then taken at different timings to capture the instantaneous development of the flow. After that, a waterproof water pump was used to produce the effect of force convection on the rising bubbles in the tunnel model to simulate ventilation of tunnel fires. For comparison, several computational simulations were performed. Two of the most critical issues to focus are the backlayering effect and the downstream smoke propagation speed due to factors such as the fire size, the ventilation speed, and the tunnel gradient. Numerical simulations were performed through the control volume approach using FDS. The turbulence model employed for computation was the Large Eddy Simulation (LES) based on Smogorinsky model.