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Flow characterization study and fire experiments in a reduced scaled tunnel

Abuaisheh, Majd Basil Abdel Muhsen
This work is an experimental study on the subject of tunnel fires, which is conducted on a ventilated 1/13 scaled tunnel model in the Fluid Mechanics Laboratory, Department of Mechanical Engineering of Middle East Technical University. In order to perform the experiments, in the first stage, the tunnel model was completely renovated, and its overall condition was improved to obtain better means of control and accuracy on the experimental measurements. In the second stage of the thesis, a flow characterization study was conducted on the flow inside the tunnel model under fire (hot flow) and cold flow conditions using Laser Doppler Anemometry (LDA) optical method to identify the ventilation velocity profile, improve its uniformity and understand the mutual effects between fire and the ventilation flow in the upstream of fire. For the hot flow cases, ethanol pools were used as the fire source. The effect of tunnel ventilation velocity on important fire parameters such as flow temperature and heat release rate of fire were investigated. Results showed that the critical ventilation velocity of the tunnel is achieved around 0.85 m/s. The flow inside the model tunnel is highly affected by the fire in the downstream due to buoyancy effect of the smoke that resists the bulk motion of the airflow. It was shown that heat release rate and gas temperature of the tunnel are functions of ventilation velocity as well.